Large artery. The structure of the artery. Human blood vessels, interesting facts

Blood circulation is the main factor in the work of the body of living beings, including humans. The term blood circulation itself refers to the circulation of blood through the vessels of the body. The circulatory system includes the heart and blood vessels: arteries and veins. The heart contracts, blood moves and circulates through the arteries and veins.

Functions of the circulatory system

1. Transport of substances that provide specific activity of cells in the body,

2.Transport of hormones,

3. Removal of metabolic products from cells,

4. Delivery of chemicals,

5. Humoral regulation (connection of organs to each other through blood),

6.Removal of toxins and other harmful substances,

7.Heat exchange,

8.Transportation of oxygen.

Circulatory pathways

Human arteries are large vessels through which blood is delivered to organs and tissues. Large arteries are divided into smaller ones - arterioles, and they in turn turn into capillaries. That is, through the arteries, the substances contained in the blood, oxygen, hormones, chemicals are delivered to the cells.

In the human body, there are two ways in which blood circulation occurs: large and small circles of blood circulation.

The structure of the pulmonary circulation

The pulmonary circulation supplies blood to the lungs. First, the right atrium contracts and blood enters the right ventricle. Then the blood is pushed into the pulmonary trunk, which branches to the pulmonary capillaries. Here the blood is saturated with oxygen and returns through the pulmonary veins back to the heart - to the left atrium.

The structure of the systemic circulation

Oxygenated blood from the left atrium passes into the left ventricle, after which it enters the aorta. The aorta is the largest human artery, from which many smaller vessels depart, then the blood is delivered through the arterioles to the organs and returns through the veins back to the right atrium, where the cycle begins anew.

Scheme of human arteries

The aorta exits the left ventricle and rises slightly - this segment of the aorta is called the "ascending aorta", then behind the sternum the aorta deviates back, forming an aortic arch, after which it descends - the descending aorta. The descending aorta branches into:

thoracic aorta,
The abdominal part of the aorta.

The abdominal part of the aorta is often called simply the abdominal artery, this is not quite the correct name, but, most importantly, to understand, we are talking about the abdominal aorta.

The ascending aorta gives rise to the coronary arteries that supply the heart.

The aortic arch gives off three human arteries:

Shoulder trunk,
Left common carotid artery
Left subclavian artery.

The arteries of the aortic arch feed the head, neck, brain, shoulder girdle, upper limbs, and diaphragm. The carotid arteries are divided into external and internal and feed the face, thyroid gland, larynx, eyeball and brain.

The subclavian artery on its side passes into the axillary - brachial - radial and ulnar arteries.

The descending aorta supplies blood to the internal organs. At level 4 of the lumbar vertebrae, the division into common iliac arteries occurs. The common iliac artery in the pelvis divides into the external and internal iliac arteries. The inner one feeds the organs of the small pelvis, and the outer one goes to the thigh and turns into the femoral artery - the popliteal - the posterior and anterior tibial arteries - the plantar and dorsal arteries.

Name of arteries

Large and small arteries are named after:

1. The organ to which blood is brought, for example: the lower thyroid artery.

2. According to the topographic feature, that is, where they pass: intercostal arteries.

Features of some arteries

It is clear that any vessel is necessary for the body. But still there are more "important", so to speak. There is a system of collateral circulation, that is, if an “accident” occurs in one vessel: thrombosis, spasm, trauma, then the entire blood flow should not stop, the blood is distributed to other vessels, sometimes even to those capillaries that are not taken into account in the “normal” blood supply. /acted.

But there are such arteries, the defeat of which is accompanied by certain symptoms, because they do not have collateral circulation. For example, if the basilar artery is clogged, then a condition such as vertebrobasilar insufficiency occurs. If time does not begin to treat the cause, that is, the "problem" in the artery, then this condition can lead to a stroke in the vertebrobasilar basin.

The wall of the arteries consists of three layers. The inner shell, tunica intima, is lined from the side of the lumen of the vessel with endothelium, under which lie the subendothelium and the internal elastic membrane; the middle one, tunica media, is built from fibers of unstriated muscle tissue, myocytes, alternating with elastic fibers; the outer shell, tunica externa, contains connective tissue fibers.

The elastic elements of the arterial wall form a single elastic frame that acts like a spring and determines the elasticity of the arteries. As they move away from the heart, the arteries divide into branches and become smaller and smaller.

The arteries closest to the heart (the aorta and its large branches) perform the main function of conducting blood. In them, counteraction to stretching by a mass of blood, which is ejected by a cardiac impulse, comes to the fore. Therefore, structures of a mechanical nature, i.e., elastic fibers and membranes, are relatively more developed in their wall. Such arteries are called elastic arteries.

In medium and small arteries, in which the inertia of the cardiac impulse is weakened and its own contraction of the vascular wall is required for the further movement of blood, the contractile function predominates. It is provided by a relatively large development of muscle tissue in the vascular wall. Such arteries are called muscular arteries. Individual arteries supply blood to whole organs or parts of them.

In relation to the organ, there are arteries that go outside the organ, before entering it - extraorganic arteries, and their continuations, branching inside it - intraorganic, or intraorganic, arteries. Lateral branches of the same trunk or branches of different trunks can be connected to each other. Such a connection of vessels before they break up into capillaries is called anastomosis, or fistula (stoma - mouth). Arteries that form anastomoses are called anastomosing (most of them).

Arteries that do not have anastomoses with neighboring trunks before they pass into capillaries are called terminal arteries (for example, in the spleen). The terminal, or terminal, arteries are more easily clogged with a blood plug (thrombus) and predispose to the formation of a heart attack (local necrosis of the organ). The last branches of the arteries become thin and small and therefore stand out under the name arterioles. An arteriole differs from an artery in that its wall has only one layer of muscle cells, thanks to which it performs a regulatory function. The arteriole continues directly into the precapillary, in which the muscle cells are scattered and do not form a continuous layer. The precapillary differs from the arteriole in that it is not accompanied by a venule. Numerous capillaries arise from the precapillary.

development of the arteries. Reflecting the transition in the process of phylogenesis from the branchial circulation to the pulmonary circulation, in a person, in the process of ontogenesis, aortic arches are first laid, which are then transformed into the arteries of the pulmonary and corporal circulations. In a 3-week-old embryo, truncus arteriosus, leaving the heart, gives rise to two arterial trunks, called the ventral aortas (right and left). The ventral aortas run in an ascending direction, then turn back onto the dorsal side of the embryo; here they, passing along the sides of the chord, go already in a downward direction and are called dorsal aortas. The dorsal aorta gradually approach each other and in the middle section of the embryo merge into one unpaired descending aorta. As the gill arches develop at the head end of the embryo, the so-called aortic arch, or artery, is formed in each of them; these arteries connect the ventral and dorsal aorta on each side.

Thus, in the region of the gill arches, the ventral (ascending) and dorsal (descending) aortas are interconnected using 6 pairs of aortic arches. In the future, part of the aortic arches and part of the dorsal aortas, especially the right one, is reduced, and large cardiac and main arteries develop from the remaining primary vessels, namely: truncus arteriosus, as noted above, is divided by the frontal septum into the ventral part, from which the pulmonary trunk is formed, and dorsal, turning into the ascending aorta. This explains the location of the aorta behind the pulmonary trunk.

It should be noted that the last pair of aortic arches in terms of blood flow, which in lungfish and amphibians acquires a connection with the lungs, also turns into two pulmonary arteries in humans - the right and left, branches of the truncus pulmonalis. At the same time, if the right sixth aortic arch is preserved only in a small proximal segment, then the left one remains throughout, forming the ductus arteriosus, which connects the pulmonary trunk with the end of the aortic arch, which is important for the blood circulation of the fetus. The fourth pair of aortic arches is preserved on both sides throughout, but gives rise to various vessels. The left 4th aortic arch together with the left ventral aorta and part of the left dorsal aorta form the aortic arch, arcus aortae. The proximal segment of the right ventral aorta turns into the brachiocephalic trunk, truncus blachiocephalicus, the right 4th aortic arch - into the beginning of the right subclavian artery extending from the named trunk, a. subclavia dextra. The left subclavian artery arises from the left dorsal aorta caudal to the last aortic arch.

The dorsal aortas in the area between the 3rd and 4th aortic arches are obliterated; in addition, the right dorsal aorta is also obliterated along the length from the origin of the right subclavian artery to the confluence with the left dorsal aorta. Both ventral aortas in the area between the fourth and third aortic arches are transformed into common carotid arteries, aa. carotides communes, and due to the above transformations of the proximal ventral aorta, the right common carotid artery turns out to be branching off from the brachiocephalic trunk, and the left one - directly from the arcus aortae. In the further course, the ventral aortas turn into external carotid arteries, aa. carotides externae. The third pair of aortic arches and the dorsal aorta in the segment from the third to the first branchial arch develop into the internal carotid arteries, aa. carotides internae, which explains that the internal carotid arteries lie more lateral in an adult than the external ones. The second pair of aortic arches turns into aa. linguales et pharyngeae, and the first pair - into the maxillary, facial and temporal arteries. When the normal course of development is disturbed, various anomalies occur.

From the dorsal aortas, a series of small paired vessels arise, running dorsally on both sides of the neural tube. Because these vessels branch off at regular intervals into the loose mesenchymal tissue located between the somites, they are called dorsal intersegmental arteries. In the neck, on both sides of the body, they are early connected by a series of anastomoses, forming longitudinal vessels - the vertebral arteries. At the level of the 6th, 7th and 8th cervical intersegmental arteries, the kidneys of the upper extremities are laid. One of the arteries, usually the 7th, grows into the upper limb and increases with the development of the arm, forming the distal subclavian artery (its proximal part develops, as already mentioned, on the right from the 4th aortic arch, on the left it grows from the left dorsal aorta, with which the 7th intersegmental arteries connect). Subsequently, the cervical intersegmental arteries are obliterated, as a result of which the vertebral arteries are branching off from the subclavian ones. The thoracic and lumbar intersegmental arteries give rise to aa. intercostales posteriores and aa. lumbales.

The visceral arteries of the abdominal cavity develop partly from aa. omphalomesentericae (yolk-mesenteric circulation) and part of the aorta. The arteries of the extremities were originally laid along the nerve trunks in the form of loops. Some of these loops (along n. femoralis) develop into the main arteries of the limbs, others (along n. medianus, n. ischiadicus) remain companions of the nerves.

Which doctors to contact for an examination of the Arteries:

What diseases are associated with Arteries:

What tests and diagnostics need to be done for the Arteries:

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You need to be very careful about your overall health. There are many diseases that at first do not manifest themselves in our body, but in the end it turns out that, unfortunately, it is too late to treat them. To do this, it is simply necessary to be examined by a doctor several times a year in order not only to prevent a terrible disease, but also to maintain a healthy spirit in the body and the body as a whole.

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km - the length of blood vessels in the human body

Interesting facts about the human circulatory system and the heart

The human circulatory system consists of veins, arteries and capillaries.

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July 8, 2013, 15:59

Elena Ivanova
July 17, 2013, 03:43 pm

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July 17, 2013, 18:17

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There are three types of blood vessels in the human body. Arteries belong to the first type. They deliver blood from the heart to various organs and tissues. The arteries branch strongly and form arterioles.

human arteries

Functions of the circulatory system

1. Transport of substances that provide specific activity of cells in the body,

2.Transport of hormones,

3. Removal of metabolic products from cells,

4. Delivery of chemicals,

5. Humoral regulation (connection of organs to each other through blood),

6.Removal of toxins and other harmful substances,

7.Heat exchange,

8.Transportation of oxygen.

Circulatory pathways

Human arteries are large vessels through which blood is delivered to organs and tissues. Large arteries are divided into smaller ones - arterioles, and they in turn turn into capillaries. That is, through the arteries, the substances contained in the blood, oxygen, hormones, chemicals are delivered to the cells.

In the human body, there are two ways in which blood circulation occurs: large and small circles of blood circulation.

The structure of the pulmonary circulation

The structure of the systemic circulation

Scheme of human arteries

The abdominal part of the aorta is often called simply the abdominal artery, this is not quite the correct name, but, most importantly, to understand, we are talking about the abdominal aorta.

The ascending aorta gives rise to the coronary arteries that supply the heart.

The aortic arch gives off three human arteries:

Shoulder trunk,
Left common carotid artery
Left subclavian artery.

The subclavian artery on its side passes into the axillary - brachial - radial and ulnar arteries.

The descending aorta supplies blood to the internal organs. At level 4 of the lumbar vertebrae, the division into common iliac arteries occurs. The common iliac artery in the pelvis divides into the external and internal iliac arteries. The inner one feeds the pelvic organs, and the outer one goes to the thigh and turns into the femoral artery - the popliteal - the posterior and anterior tibial arteries - the plantar and dorsal arteries.

Name of arteries

Large and small arteries are named after:

1. The organ to which blood is brought, for example: the lower thyroid artery.

2. According to the topographic feature, that is, where they pass: intercostal arteries.

Features of some arteries

1 comment on the entry “Human arteries”

What a complex mechanism - the circulatory system!

How many arteries does a person have

The blood supply system includes all the circulatory organs that produce blood, enrich it with oxygen, and carry it throughout the body. The aorta - the largest artery - is included in a large circle of water supply.

Living beings cannot exist without a circulatory system. In order for normal life to proceed at the proper level, blood must regularly flow to all organs and all parts of the body. The circulatory system includes the heart, arteries, veins - all blood and hematopoietic vessels and organs.

Arteries are blood vessels that pump blood passing through the heart, already enriched with oxygen. The largest artery is the aorta. It "takes" the blood leaving the left side of the heart. Its diameter is 2.5 cm. The walls of the arteries are very strong - they are designed for systolic pressure, which is determined by the rhythm of the heart contractions.

But not all arteries carry arterial blood. Among the arteries there is an exception - the pulmonary trunk. Through it, blood rushes to the respiratory organs, where it will subsequently be enriched with oxygen.

In addition, there are systemic diseases in which the arteries can contain mixed blood. An example is heart disease. But keep in mind that this is not the norm.

The heart rate can be controlled by the pulsation of the arteries. In order to count the beats of the heart, it is enough to press the artery with your finger where it is located closer to the surface of the skin.

The circulation of the body can be classified into a small and a large circle. The small one is responsible for the lungs: the right atrium contracts, pushing blood into the right ventricle. From there, it passes into the pulmonary capillaries, is enriched with oxygen and again goes into the left atrium.

Arterial blood in a large circle, which is already saturated with oxygen, rushes into the left ventricle, and from it the aorta. Through small vessels - arterioles - it is delivered to all body systems, and then, through the veins, it goes to the right atrium.

The veins carry blood to the heart for oxygenation, and they are not subjected to high pressure. Therefore, the venous walls are thinner than the arterial ones. The largest vein has a diameter of 2.5 cm. Small veins are called venules. Among the veins there is also an exception - the pulmonary vein. It carries oxygenated blood from the lungs. Veins have internal valves that prevent blood from backflowing. Violation of the internal valves causes varicose veins of varying severity.

A large artery - the aorta - is located as follows: the ascending part leaves the left ventricle, the trunk deviates behind the sternum - this is the aortic arch, and goes down, forming the descending part. The descending aortic line consists of the abdominal and thoracic aorta.

The ascending line carries blood to the arteries, which are responsible for cardiac blood supply. They are called crowns.

From the aortic arch, blood flows into the left subclavian artery, the left common carotid artery, and into the brachiocephalic trunk. They carry oxygen to the upper parts of the body: the brain, neck, upper limbs.

One goes outside, the second inside. One feeds the parts of the brain, the other - the face, thyroid gland, organs of vision ... The subclavian artery carries blood to smaller arteries: axillary, radial, etc.

The descending part of the aorta supplies the internal organs. The division into two iliac arteries, called internal and external, occurs at the level of the lower back, its fourth vertebra. The internal carries blood to the pelvic organs - the external to the limbs.

Violation of the blood supply is fraught with serious problems for the whole body. The closer the artery is to the heart, the more damage in the body in case of violation of its work.

The largest artery of the body performs an important function - it carries blood into arterioles, small branches. If it is damaged, the normal functioning of the whole organism is disrupted.

Where are arteries located in humans?

Arteries are blood vessels that carry oxygenated blood to organs and muscles. Through some of these vessels, oxygenated blood (venous) also passes. The largest arteries depart from the lungs and heart, run parallel to the spine and the main bones of the skeleton. The largest artery, the aorta, is located slightly above and adjacent to the heart. It is divided into celiac and brachiocephalic trunks.

The celiac trunk runs strictly parallel to the spine and in the pelvic area is divided into two femoral arteries. The brachiocephalic trunk divides into the left and right subclavian arteries, from which the brachial arteries emerge, supplying blood to the forearms and arms.

human blood vessels

1 - dorsal artery of the foot; 2 - anterior tibial artery (with accompanying veins); 3 - femoral artery; 4 - femoral vein; 5 - superficial palmar arch; 6 - right external iliac artery and right external iliac vein; 7-right internal iliac artery and right internal iliac vein; 8 - anterior interosseous artery; 9 - radial artery (with accompanying veins); 10 - ulnar artery (with accompanying veins); 11 - inferior vena cava; 12 - superior mesenteric vein; 13 - right renal artery and right renal vein; 14 - portal vein; 15 and 16 - saphenous veins of the forearm; 17- brachial artery (with accompanying veins); 18 - superior mesenteric artery; 19 - right pulmonary veins; 20 - right axillary artery and right axillary vein; 21 - right pulmonary artery; 22 - superior vena cava; 23 - right brachiocephalic vein; 24 - right subclavian vein and right subclavian artery; 25 - right common carotid artery; 26 - right internal jugular vein; 27 - external carotid artery; 28 - internal carotid artery; 29 - brachiocephalic trunk; 30 - external jugular vein; 31 - left common carotid artery; 32 - left internal jugular vein; 33 - left brachiocephalic vein; 34 - left subclavian artery; 35 - aortic arch; 36 - left pulmonary artery; 37 - pulmonary trunk; 38 - left pulmonary veins; 39 - ascending aorta; 40 - hepatic veins; 41 - splenic artery and vein; 42 - celiac trunk; 43 - left renal artery and left renal vein; 44 - inferior mesenteric vein; 45 - right and left testicular arteries (with accompanying veins); 46 - inferior mesenteric artery; 47 - median vein of the forearm; 48 - abdominal aorta; 49 - left common iliac artery; 50 - left common iliac vein; 51 - left internal iliac artery and left internal iliac vein; 52 - left external iliac artery and left external iliac vein; 53 - left femoral artery and left femoral vein; 54 - venous palmar network; 55 - a large saphenous (hidden) vein; 56 - small saphenous (hidden) vein; 57 - venous network of the rear of the foot.

1 - venous network of the rear of the foot; 2 - small saphenous (hidden) vein; 3 - femoral-popliteal vein; 4-6 - venous network of the rear of the Hand; 7 and 8 - saphenous veins of the forearm; 9 - posterior ear artery; 10 - occipital artery; 11- superficial cervical artery; 12 - transverse artery of the neck; 13 - suprascapular artery; 14 - posterior circumflex artery; 15 - artery, enveloping the scapula; 16 - deep artery of the shoulder (with accompanying veins); 17 - posterior intercostal arteries; 18 - superior gluteal artery; 19 - lower gluteal artery; 20 - posterior interosseous artery; 21 - radial artery; 22 - dorsal carpal branch; 23 - perforating arteries; 24 - external upper artery of the knee joint; 25 - popliteal artery; 26-popliteal vein; 27-external lower artery of the knee joint; 28 - posterior tibial artery (with accompanying veins); 29 - peroneal, artery.

The walls of arterial vessels consist of three main layers: the outer shell - tunica adventitia, the middle shell - tunica media, the inner shell - tunica interna, or intima. These layers can be distinguished not only microscopically, but also with the help of a binocular loupe when dissecting large segments of arteries. According to the predominance of morphological elements in the walls, the arteries are divided into elastic type, muscular and mixed arteries.

The largest arteries located near the heart, such as the aorta, brachiocephalic trunk, subclavian, carotid and other arteries, take on the pressure of the blood column ejected with great force during the systole of the left ventricle of the heart. They are elastic type arteries, as they must have strong elastic walls in order to withstand this pressure. By structure, arterial vessels of a smaller caliber are vessels of a muscular, mixed type, having a much better developed middle muscle layer, the contraction of which causes the blood to move up to the arterioles, precapillaries and capillaries. Thus, the structure of the arteries is closely related to the functional significance of one or another segment of the arterial system. On section, the wall of a fresh, non-fixed elastic type artery appears yellowish due to the predominance of elastic fibers. The section of the wall of the structure of the arterial vessel of the muscular type has a reddish tint due to the well-developed compact muscle layer. However, the backbone of arteries of all types is their elastic framework, built from elastic connective tissue fibers. The inclusion of the walls of the arteries of such an elastic framework explains their properties: elasticity, extensibility in the transverse and longitudinal directions, as well as the preservation of the gaping lumen by the arteries when they are ruptured or cut. N. N. Anichkov, in addition to large accumulations in the structure of the arteries of elastic fibers, observed the presence of networks of thin connective tissue precollagone or argyrophilic fibers.

outer shell- t. adventitia - formed to varying degrees by a developed layer of longitudinal bundles of collagen with an admixture of elastic fibers. The networks of these fibers are especially well developed at the border of the middle shell, forming here a dense layer of lamina elastica externa. From the outside, adventitia is tightly connected with the connective tissue case in the structure of the artery, which is part of the sheath of the vascular bundle. It can be considered as the inner layer of the vascular sheath. At the same time, the walls of the arteries, as well as the entire neurovascular bundle, are intimately connected with the processes of the fascia of the corresponding areas.

In the connective tissue surrounding the blood vessels in many places, it is possible to identify slit-like spaces, called perivascular spaces, through which, as a number of researchers believe, tissue fluid circulates. From the connective tissue sheath through the adventitia, the vessels that feed the vascular wall and the corresponding nerve conductors of the vessels penetrate into the thickness of the vessel wall.

In large arteries, the adventitia is developed; in the walls of medium-sized arteries, it is even relatively thicker. Arteries, small in structure, have weak adventitia, in the smallest vessels it is almost not developed and merges with the connective tissue surrounding them.

Middle shell mainly formed by several layers of smooth muscle fibers, having a predominantly circular arrangement. The degree of development of the muscle layer in the arteries of different calibers is not the same: the muscle layer is developed in the structure of medium-sized arteries. With a decrease in the size of the vessels, the number of muscle layers gradually decreases, so that in the structure of the smallest arteries there is only one layer of circularly located muscle fibers, and in the arterioles there are only individual muscle fibers.

Among the muscle layers in the structure of the middle shell of the arteries there is a network of elastic fibers; this network is not interrupted anywhere and is in connection with the elastic fibers of the inner and outer walls of the vessel, connecting them and creating the frame of the arterial wall.

Inner shell arteries - tunica interna s. intima, characterized by its smooth surface, is formed by a layer of endotheliocytes. Beneath this layer lies the subendothelial layer, which is called the stratum proprium intimae. It consists of a connective tissue layer with thin elastic fibers. The connective tissue layer includes special stellate cells located under the endothelium in the form of a continuous layer. Subendothelial cells determine a number of processes that occur during regeneration and during the restructuring of the vascular wall. Endothelial regeneration is truly amazing. Kunlin from Leriche's laboratory removed the endothelium from dogs over a large area, in a few days it was completely restored. The same phenomenon is observed during endarterectomy - removal of a thrombus along with the inner shell of the vessel.

A layer of elastic tissue is directly adjacent to the subendothelial layer, forming an elastic fenestrated membrane. It consists of a dense dense network of thick fibers. Membrana elastica interna has a close relationship with the subendothelial layer and its elastic network, which allows it to be included in the inner lining of the artery structure. In turn, the outer layers of the inner membrane are adjacent to the middle shell of the arterial wall and its elastic elements are in direct connection with the network of elastic fibers. In small vessels, the inner shell of the structure of the artery consists of only one layer of endothelial cells, which is adjacent directly to the internal elastic membrane. The intima may also have a small amount of muscle elements in the form of longitudinally running smooth fibers.

The walls of arterial vessels are supplied with their own blood vessels - arteries and veins, lymphatic vessels and have lymphatic spaces.

blood supply arterial walls are usually carried out by branches of small arterial vessels located in the connective tissue near the blood trunks. The branches that feed the walls of the arterial vessels form anastomoses between themselves, due to which an extramural network appears around the circumference of the vessel in the form of an arterial clutch. This para-arterial network forms a kind of channel around the arterial trunk, which plays a role not only in the blood supply to the walls of the artery itself due to aa. vasorum, but also plays a role in the formation of additional collaterals.

Arising from the paraarterial network, the stems penetrate through the adventitia into the depths of the structure of the artery, forming intramural networks in it. The terminal branches of these arterial vessels reach the tunica media and, without entering the inner shell, devoid of vessels, form a capillary network in the middle layers of the tunicae mediae.

It should be emphasized that the deepest layers of the middle shell, as well as the intima, do not have their own blood vessels and are fed by the lymphatic fluid circulating in them. The latter, formed from the blood plasma located in the lumen of the arterial vessel, enters the lymphatic tracts and small veins of the middle membrane and flows through the corresponding vessels of the adventitia into the lymphatic tracts accompanying the blood vessels.

innervation The structure of the arteries is carried out by the somatic (afferent fibers) and the autonomic nervous system. The latter consists of sympathetic and parasympathetic fibers that perform vasomotor innervation.

The article was prepared and edited by: surgeon

The heart is the most important organ for maintaining the life of the human body. Through its rhythmic contractions, it carries the blood throughout the body, providing nourishment to all the elements.

The coronary arteries are responsible for supplying oxygen to the heart.. Another common name for them is coronary vessels.

The cyclical repetition of this process ensures uninterrupted blood supply, which keeps the heart in working order.

Coronaries are a whole group of vessels that supply blood to the heart muscle (myocardium). They carry oxygen-rich blood to all parts of the heart.

The outflow, depleted of its content (venous) blood, is carried out by 2/3 of the large vein, medium and small, which are woven into a single extensive vessel - the coronary sinus. The remainder is excreted by the anterior and Tebezian veins.

When the heart ventricles contract, the shutter closes off the arterial valve. The coronary artery at this point is almost completely blocked and blood circulation in this area stops.

The flow of blood resumes after the opening of the entrances to the arteries. The filling of the sinuses of the aorta occurs due to the impossibility of returning blood to the cavity of the left ventricle, after its relaxation, because. at this time, the dampers are closed.

Important! The coronary arteries are the only possible source of blood supply for the myocardium, so any violation of their integrity or mechanism of operation is very dangerous.

Scheme of the structure of the vessels of the coronary bed

The structure of the coronary network has a branched structure: several large branches and many smaller ones.

Arterial branches originate from the aortic bulb, immediately after the valve of the aortic valve and, bending around the surface of the heart, carry out blood supply to its different departments.

These vessels of the heart consist of three layers:

Initial - endothelium;
Muscular fibrous layer;
Adventitia.

This layering makes the walls of the vessels very elastic and durable.. This contributes to proper blood flow even under conditions of high stress on the cardiovascular system, including during intense sports, which increase the speed of blood flow up to five times.

Types of coronary arteries

All vessels that make up a single arterial network, based on the anatomical details of their location, are divided into:

Basic (epicardial)
Adnexal (other branches):

Right coronary artery. Its main duty is to feed the right heart ventricle. Partially supplies oxygen to the wall of the left heart ventricle and the common septum.
Left coronary artery. Provides blood flow to all other cardiac departments. It is a branching into several parts, the number of which depends on the personal characteristics of a particular organism.
envelope branch. It is a branch from the left side and feeds the septum of the corresponding ventricle. It is subject to increased thinning in the presence of the slightest damage.
Anterior descending(large interventricular) branch. It also comes from the left artery. It forms the basis for the supply of nutrients to the heart and the septum between the ventricles.
subendocardial arteries. They are considered part of the overall coronary system, but run deep within the heart muscle (myocardium) rather than on the surface itself.

All arteries are located directly on the surface of the heart itself (except for subendocardial vessels). Their work is regulated by their own internal processes, which also control the exact volume of blood supplied to the myocardium.

Variants of dominant blood supply

Dominant, feeding the posterior descending branch of the artery, which can be either right or left.

Determine the general type of blood supply to the heart:

The right blood supply is dominant if this branch departs from the corresponding vessel;
The left type of nutrition is possible if the posterior artery is a branch from the circumflex vessel;
The blood flow can be considered balanced if it comes simultaneously from the right trunk and from the circumflex branch of the left coronary artery.

Reference. The predominant source of nutrition is determined on the basis of the total flow of blood flow to the atrioventricular node.

In the vast majority of cases (about 70%), a dominant right blood supply is observed in a person. Equivalent work of both arteries is present in 20% of people. Left dominant nutrition through the blood is manifested only in the remaining 10% of cases.

What is coronary heart disease?

Ischemic heart disease (CHD), also referred to as coronary heart disease (CHD), is any disease associated with a sharp deterioration in the blood supply to the heart due to insufficient activity of the coronary system.

IHD can be either acute or chronic.

Most often, it manifests itself against the background of atherosclerosis of the arteries, which occurs due to a general thinning or violation of the integrity of the vessel.

A plaque is formed at the site of damage, which gradually increases in size, narrows the lumen and thereby prevents the normal flow of blood.

The list of coronary diseases includes:

angina;
Arrhythmia;
Embolism;
Arteritis;
heart attack;
Distortion of the coronary arteries;
Death due to cardiac arrest.

Coronary disease is characterized by undulating jumps in the general condition, in which the chronic phase rapidly passes into the acute phase and vice versa.

How pathologies are determined

Coronary diseases are manifested by severe pathologies, the initial form of which is angina pectoris. Subsequently, it develops into more serious diseases, and strong nervous or physical stress is no longer required for the onset of attacks.

angina pectoris

Scheme of changes in the coronary artery

In everyday life, such a manifestation of IHD is sometimes called "toad on the chest." This is due to the occurrence of asthma attacks, which are accompanied by pain.

Initially, symptoms begin in the chest area, after which they spread to the left back, shoulder blade, collarbone and lower jaw (rarely).

Pain is the result of oxygen starvation of the myocardium, the aggravation of which occurs in the process of physical, mental work, excitement or overeating.

myocardial infarction

Cardiac infarction is a very serious condition, accompanied by the death of certain parts of the myocardium (necrosis). This is due to a continuous cessation or incomplete flow of blood into the organ, which, most often, occurs against the background of the formation of a blood clot in the coronary vessels.

blockage of a coronary artery

Sharp pain in the chest, which is given to neighboring areas;
Heaviness, tightness of breath;
Trembling, muscle weakness, sweating;
Coronary pressure is greatly reduced;
Attacks of nausea, vomiting;
Fear, sudden panic attacks.

The part of the heart that has undergone necrosis does not perform its functions, and the remaining half continues its work in the same mode. This can cause the dead section to rupture. If a person is not provided with urgent medical care, then the risk of death is high.

Heart rhythm disorder

It is provoked by a spasmodic artery or untimely impulses that arose against the background of impaired conduction of the coronary vessels.

The main symptoms of manifestation:

Sensation of tremors in the region of the heart;
A sharp fading of contractions of the heart muscle;
dizziness, blurriness, darkness in the eyes;
The severity of breathing;
Unusual manifestation of passivity (in children);
Lethargy in the body, constant fatigue;
Pressing and prolonged (sometimes sharp) pain in the heart.

Rhythm failure often manifests itself due to a slowdown in metabolic processes if the endocrine system is out of order. It can also be a catalyst for long-term use of many drugs.

This concept is the definition of insufficient activity of the heart, which is why there is a shortage of blood supply to the whole organism.

Pathology can develop as a chronic complication of arrhythmia, heart attack, weakening of the heart muscle.

Acute manifestation is most often associated with the intake of toxic substances, injuries and a sharp deterioration in the course of other heart diseases.

This condition needs urgent treatment, otherwise the likelihood of death is high.

Against the background of diseases of the coronary vessels, the development of heart failure is often diagnosed.

The main symptoms of manifestation:

Violation of the heart rhythm;
Difficulty breathing;
Coughing fits;
Blurring and darkening in the eyes;
Swelling of the veins in the neck;
Swelling of the legs, accompanied by painful sensations;
Disconnection of consciousness;
Strong fatigue.

Often this condition is accompanied by ascites (accumulation of water in the abdominal cavity) and an enlarged liver. If a patient has persistent hypertension or diabetes mellitus, it is impossible to make a diagnosis.

coronary insufficiency

Heart failure is the most common type of ischemic disease. It is diagnosed if the circulatory system has partially or completely stopped supplying blood to the coronary arteries.

The main symptoms of manifestation:

Severe pain in the region of the heart;
Feeling of "lack of space" in the chest;
Discoloration of urine and its increased excretion;
Paleness of the skin, a change in its shade;
The severity of the work of the lungs;
Sialorrhoea (intense salivation);
Nausea, vomiting, rejection of the usual food.

In the acute form, the disease is manifested by an attack of sudden cardiac hypoxia due to arterial spasm. Chronic course is possible due to angina pectoris against the background of accumulation of atherosclerotic plaques.

There are three stages in the course of the disease:

Initial (mild);
Expressed;
A severe stage that, if not properly treated, can lead to death.

Causes of vascular problems

There are several factors contributing to the development of CHD. Many of them are a manifestation of insufficient care for one's health.

Important! Today, according to medical statistics, cardiovascular diseases are the number 1 cause of death in the world.

Every year, more than two million people die from coronary artery disease, most of whom are part of the population of "prosperous" countries, with a comfortable sedentary lifestyle.

The main causes of ischemic disease can be considered:

Tobacco smoking, incl. passive inhalation of smoke;
Eating foods high in cholesterol
Excess weight (obesity);
Hypodynamia, as a consequence of a systematic lack of movement;
Exceeding the norm of sugar in the blood;
Frequent nervous tension;
Arterial hypertension.

There are also factors independent of a person that affect the state of blood vessels: age, heredity and gender.

Women are more resistant to such ailments and therefore they are characterized by a long course of the disease. And men are more likely to suffer precisely from the acute form of pathologies that end in death.

Methods of treatment and prevention of the disease

Correction of the condition or complete cure (in rare cases) is possible only after a detailed study of the causes of the manifestation of the disease.

For this, the necessary laboratory and instrumental studies are carried out. After that, a therapy plan is drawn up, the basis of which is drugs.

Treatment involves the use of the following medications:

Surgical intervention is prescribed in case of ineffectiveness of traditional therapy. To better nourish the myocardium, coronary bypass surgery is used - they connect the coronary and external veins where the intact section of the vessels is located.

Coronary artery bypass grafting is a complex method that is performed on an open heart, therefore it is used only in difficult situations when it is impossible to do without replacing the narrowed sections of the artery.

Dilatation may be performed if the disease is associated with overproduction of the arterial wall layer. This intervention involves the introduction of a special balloon into the lumen of the vessel, expanding it in places of a thickened or damaged shell.

Heart before and after chamber dilatation

Reducing the risk of complications

Own preventive measures reduce the risk of coronary artery disease. They also minimize the negative consequences during the rehabilitation period after treatment or surgery.

The simplest advice available to everyone:

Rejection of bad habits;
Balanced diet (special attention to Mg and K);
Daily walks in the fresh air;
Physical activity;
Control of blood sugar and cholesterol;
Hardening and sound sleep.

The coronary system is a very complex mechanism that needs to be treated with care. The pathology that has manifested once is steadily progressing, accumulating more and more new symptoms and worsening the quality of life, therefore, the recommendations of specialists and the observance of elementary health standards should not be neglected.

Systematic strengthening of the cardiovascular system will allow you to keep the vigor of the body and soul for many years.

Video. Angina. Myocardial infarction. Heart failure. How to protect your heart.

The heart contracts, blood moves and circulates through the arteries and veins.

Functions of the circulatory system

1. Transport of substances that provide specific activity of cells in the body,

2.Transport of hormones,

3. Removal of metabolic products from cells,

4. Delivery of chemicals,

5. Humoral regulation (connection of organs to each other through blood),

6.Removal of toxins and other harmful substances,

7.Heat exchange,

8.Transportation of oxygen.

Circulatory pathways

In the human body, there are two ways in which blood circulation occurs: large and small circles of blood circulation.

The structure of the pulmonary circulation

The structure of the systemic circulation

Scheme of human arteries

The abdominal part of the aorta is often called simply the abdominal artery, this is not quite the correct name, but, most importantly, to understand, we are talking about the abdominal aorta.

The ascending aorta gives rise to the coronary arteries that supply the heart.

The aortic arch gives off three human arteries:

Shoulder trunk,
Left common carotid artery
Left subclavian artery.

The subclavian artery on its side passes into the axillary - brachial - radial and ulnar arteries.

The descending aorta supplies blood to the internal organs. At level 4 of the lumbar vertebrae, the division into common iliac arteries occurs. The common iliac artery in the pelvis divides into the external and internal iliac arteries. The inner one feeds the pelvic organs, and the outer one goes to the thigh and turns into the femoral artery - the popliteal - the posterior and anterior tibial arteries - the plantar and dorsal arteries.

Name of arteries

Large and small arteries are named after:

1. The organ to which blood is brought, for example: the lower thyroid artery.

2. According to the topographic feature, that is, where they pass: intercostal arteries.

Features of some arteries

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What a complex mechanism - the circulatory system!

Functions of blood vessels - arteries, capillaries, veins

What are vessels?

Vessels are tubular formations that extend throughout the human body and through which blood moves. The pressure in the circulatory system is very high because the system is closed. According to this system, the blood circulates quite quickly.

After many years, obstructions to the movement of blood - plaques - form on the vessels. These are formations on the inside of the vessels. Thus, the heart must pump blood more intensively in order to overcome the obstructions in the vessels, which disrupts the work of the heart. At this point, the heart can no longer deliver blood to the organs of the body and can not cope with the work. But at this stage it is still possible to recover. Vessels are cleansed of salts and cholesterol layers. (Read also: Cleansing of vessels)

When the vessels are cleansed, their elasticity and flexibility return. Many diseases associated with blood vessels go away. These include sclerosis, headaches, a tendency to a heart attack, paralysis. Hearing and vision are restored, varicose veins are reduced. The state of the nasopharynx returns to normal.

human blood vessels

Blood circulates through the vessels that make up the systemic and pulmonary circulation.

All blood vessels are made up of three layers:

The inner layer of the vascular wall is formed by endothelial cells, the surface of the vessels inside is smooth, which facilitates the movement of blood through them.

The middle layer of the walls provides strength to blood vessels, consists of muscle fibers, elastin and collagen.

The upper layer of the vascular walls is made up of connective tissues, it separates the vessels from nearby tissues.

arteries

The walls of the arteries are stronger and thicker than those of the veins, as the blood moves through them with greater pressure. Arteries carry oxygenated blood from the heart to the internal organs. In the dead, the arteries are empty, which is found at autopsy, so it was previously believed that the arteries are air tubes. This was reflected in the name: the word "artery" consists of two parts, translated from Latin, the first part aer means air, and tereo means to contain.

Depending on the structure of the walls, two groups of arteries are distinguished:

The elastic type of arteries is the vessels located closer to the heart, these include the aorta and its large branches. The elastic framework of the arteries must be strong enough to withstand the pressure with which blood is ejected into the vessel from heart contractions. The fibers of elastin and collagen, which make up the frame of the middle wall of the vessel, help to resist mechanical stress and stretching.

Due to the elasticity and strength of the walls of the elastic arteries, blood continuously enters the vessels and its constant circulation is ensured to nourish organs and tissues, supplying them with oxygen. The left ventricle of the heart contracts and forcefully ejects a large volume of blood into the aorta, its walls stretch, containing the contents of the ventricle. After relaxation of the left ventricle, blood does not enter the aorta, the pressure is weakened, and blood from the aorta enters other arteries, into which it branches. The walls of the aorta regain their former shape, as the elastin-collagen framework provides them with elasticity and resistance to stretching. Blood moves continuously through the vessels, coming in small portions from the aorta after each heartbeat.

The elastic properties of arteries also ensure the transmission of vibrations along the walls of blood vessels - this is a property of any elastic system under mechanical influences, which is played by a heart impulse. The blood hits the elastic walls of the aorta, and they transmit vibrations along the walls of all the vessels of the body. Where the vessels come close to the skin, these vibrations can be felt as a weak pulsation. Based on this phenomenon, methods for measuring the pulse are based.

Muscular arteries in the middle layer of the walls contain a large number of smooth muscle fibers. This is necessary to ensure blood circulation and the continuity of its movement through the vessels. The vessels of the muscular type are located farther from the heart than the arteries of the elastic type, therefore, the force of the cardiac impulse in them weakens, in order to ensure further movement of the blood, it is necessary to contract the muscle fibers. When the smooth muscles of the inner layer of the arteries contract, they narrow, and when they relax, they expand. As a result, blood moves through the vessels at a constant speed and enters the organs and tissues in a timely manner, providing them with nutrition.

Another classification of arteries determines their location in relation to the organ whose blood supply they provide. Arteries that pass inside the organ, forming a branching network, are called intraorgan. Vessels located around the organ, before entering it, are called extraorganic. Lateral branches that originate from the same or different arterial trunks may reconnect or branch into capillaries. At the point of their connection, before branching into capillaries, these vessels are called anastomosis or fistula.

Arteries that do not anastomose with neighboring vascular trunks are called terminal. These include, for example, the arteries of the spleen. The arteries that form fistulas are called anastomizing, most of the arteries belong to this type. The terminal arteries have a greater risk of blockage by a thrombus and a high susceptibility to a heart attack, as a result of which part of the organ may die.

In the last branches, the arteries become very thin, such vessels are called arterioles, and the arterioles already pass directly into the capillaries. Arterioles contain muscle fibers that perform a contractile function and regulate the flow of blood into the capillaries. The layer of smooth muscle fibers in the walls of arterioles is very thin compared to the artery. The branching point of the arteriole into capillaries is called the precapillary, here the muscle fibers do not form a continuous layer, but are located diffusely. Another difference between a precapillary and an arteriole is the absence of a venule. The precapillary gives rise to numerous branches into the smallest vessels - capillaries.

capillaries

Capillaries are the smallest vessels, the diameter of which varies from 5 to 10 microns, they are present in all tissues, being a continuation of the arteries. Capillaries provide tissue metabolism and nutrition, supplying all body structures with oxygen. In order to ensure the transfer of oxygen and nutrients from the blood to the tissues, the capillary wall is so thin that it consists of only one layer of endothelial cells. These cells are highly permeable, so through them the substances dissolved in the liquid enter the tissues, and the metabolic products return to the blood.

The number of working capillaries in different parts of the body varies - in large numbers they are concentrated in the working muscles, which need a constant blood supply. For example, in the myocardium (the muscular layer of the heart), up to two thousand open capillaries are found per square millimeter, and in skeletal muscles there are several hundred capillaries per square millimeter. Not all capillaries function at the same time - many of them are in reserve, in a closed state, to start working when necessary (for example, during stress or increased physical activity).

Capillaries anastomize and, branching out, make up a complex network, the main links of which are:

Arterioles - branch into precapillaries;

Precapillaries - transitional vessels between arterioles and capillaries proper;

Venules are places where capillaries pass into veins.

Each type of vessel that makes up this network has its own mechanism for the transfer of nutrients and metabolites between the blood they contain and nearby tissues. The musculature of larger arteries and arterioles is responsible for the promotion of blood and its entry into the smallest vessels. In addition, the regulation of blood flow is also carried out by the muscular sphincters of pre- and post-capillaries. The function of these vessels is mainly distributive, while true capillaries perform a trophic (nutritional) function.

Veins are another group of vessels, the function of which, unlike arteries, is not to deliver blood to tissues and organs, but to ensure its entry into the heart. To do this, the movement of blood through the veins occurs in the opposite direction - from tissues and organs to the heart muscle. Due to the difference in functions, the structure of the veins is somewhat different from the structure of the arteries. The factor of strong pressure that blood exerts on the walls of blood vessels is much less manifested in veins than in arteries, therefore, the elastin-collagen framework in the walls of these vessels is weaker, and muscle fibers are also represented in a smaller amount. That is why veins that do not receive blood collapse.

Like arteries, veins branch widely to form networks. Many microscopic veins merge into single venous trunks that lead to the largest vessels that flow into the heart.

The movement of blood through the veins is possible due to the action of negative pressure on it in the chest cavity. Blood moves in the direction of the suction force into the heart and chest cavity, in addition, its timely outflow provides a smooth muscle layer in the walls of blood vessels. The movement of blood from the lower extremities upwards is difficult, therefore, in the vessels of the lower body, the muscles of the walls are more developed.

In order for the blood to move towards the heart, and not in the opposite direction, valves are located in the walls of the venous vessels, represented by a fold of the endothelium with a connective tissue layer. The free end of the valve freely directs blood towards the heart, and the outflow is blocked back.

Most veins run next to one or more arteries: small arteries usually have two veins, and larger ones have one. Veins that do not accompany any arteries occur in the connective tissue under the skin.

The walls of larger vessels are nourished by smaller arteries and veins that originate from the same trunk or from neighboring vascular trunks. The entire complex is located in the connective tissue layer surrounding the vessel. This structure is called the vascular sheath.

The venous and arterial walls are well innervated, contain a variety of receptors and effectors, well connected with the leading nerve centers, due to which the automatic regulation of blood circulation is carried out. Thanks to the work of the reflexogenic sections of blood vessels, the nervous and humoral regulation of metabolism in tissues is ensured.

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Functional groups of vessels

According to the functional load, the entire circulatory system is divided into six different groups of vessels. Thus, in the human anatomy, shock-absorbing, exchange, resistive, capacitive, shunting and sphincter vessels can be distinguished.

Cushioning Vessels

This group mainly includes arteries in which a layer of elastin and collagen fibers is well represented. It includes the largest vessels - the aorta and the pulmonary artery, as well as the areas adjacent to these arteries. The elasticity and resilience of their walls provides the necessary shock-absorbing properties, due to which the systolic waves that occur during heart contractions are smoothed out.

The cushioning effect in question is also called the Windkessel effect, which in German means "compression chamber effect".

To demonstrate this effect, the following experiment is used. Two tubes are attached to a container filled with water, one of an elastic material (rubber) and the other of glass. From a hard glass tube, water splashes out in sharp intermittent shocks, and from a soft rubber one it flows evenly and constantly. This effect is explained by the physical properties of the tube materials. The walls of an elastic tube are stretched under the action of fluid pressure, which leads to the emergence of the so-called elastic stress energy. Thus, the kinetic energy that appears due to pressure is converted into potential energy, which increases the voltage.

The kinetic energy of cardiac contraction acts on the walls of the aorta and large vessels that depart from it, causing them to stretch. These vessels form a compression chamber: the blood entering them under the pressure of the systole of the heart stretches their walls, the kinetic energy is converted into the energy of elastic tension, which contributes to the uniform movement of blood through the vessels during the diastole.

The arteries located farther from the heart are of the muscular type, their elastic layer is less pronounced, they have more muscle fibers. The transition from one type of vessel to another occurs gradually. Further blood flow is provided by the contraction of the smooth muscles of the muscular arteries. At the same time, the smooth muscle layer of large elastic type arteries practically does not affect the diameter of the vessel, which ensures the stability of hydrodynamic properties.

Resistive vessels

Resistive properties are found in arterioles and terminal arteries. The same properties, but to a lesser extent, are characteristic of venules and capillaries. The resistance of the vessels depends on their cross-sectional area, and the terminal arteries have a well-developed muscle layer that regulates the lumen of the vessels. Vessels with a small lumen and thick, strong walls provide mechanical resistance to blood flow. The developed smooth muscles of resistive vessels provide regulation of the volumetric blood velocity, controls the blood supply to organs and systems due to cardiac output.

Vessels-sphincters

Sphincters are located in the terminal sections of the precapillaries; when they narrow or expand, the number of working capillaries that provide tissue trophism changes. With the expansion of the sphincter, the capillary goes into a functioning state, in non-working capillaries, the sphincters are narrowed.

exchange vessels

Capillaries are vessels that perform an exchange function, carry out diffusion, filtration and trophism of tissues. Capillaries cannot independently regulate their diameter, changes in the lumen of the vessels occur in response to changes in the sphincters of the precapillaries. The processes of diffusion and filtration occur not only in capillaries, but also in venules, so this group of vessels also belongs to the exchange ones.

capacitive vessels

Vessels that act as reservoirs for large volumes of blood. Most often, capacitive vessels include veins - the peculiarities of their structure allow them to hold more than 1000 ml of blood and throw it out as needed, ensuring the stability of blood circulation, uniform blood flow and full blood supply to organs and tissues.

In humans, unlike most other warm-blooded animals, there are no special reservoirs for depositing blood from which it could be ejected as needed (in dogs, for example, this function is performed by the spleen). Veins can accumulate blood to regulate the redistribution of its volumes throughout the body, which is facilitated by their shape. Flattened veins contain large volumes of blood, while not stretching, but acquiring an oval lumen shape.

Capacitive vessels include large veins in the womb, veins in the subpapillary plexus of the skin, and liver veins. The function of depositing large volumes of blood can also be performed by the pulmonary veins.

Shunt vessels

Shunt vessels are an anastomosis of arteries and veins, when they are open, blood circulation in the capillaries is significantly reduced. Shunt vessels are divided into several groups according to their function and structural features:

Cardiac vessels - these include the elastic type arteries, vena cava, pulmonary arterial trunk and pulmonary vein. They begin and end with a large and small circle of blood circulation.

The main vessels are large and medium-sized vessels, veins and arteries of the muscular type, located outside the organs. With their help, blood is distributed to all parts of the body.

Organ vessels - intraorgan arteries, veins, capillaries that provide trophism to the tissues of internal organs.

Diseases of the blood vessels

The most dangerous vascular diseases that pose a threat to life are: aneurysm of the abdominal and thoracic aorta, arterial hypertension, ischemic disease, stroke, renal vascular disease, atherosclerosis of the carotid arteries.

Diseases of the vessels of the legs - a group of diseases that lead to impaired blood circulation through the vessels, pathologies of the valves of the veins, impaired blood clotting.

Atherosclerosis of the lower extremities - the pathological process affects large and medium-sized vessels (aorta, iliac, popliteal, femoral arteries), causing their narrowing. As a result, the blood supply to the limbs is disturbed, severe pain appears, and the patient's performance is impaired.

Varicose veins - a disease that results in the expansion and lengthening of the veins of the upper and lower extremities, thinning of their walls, the formation of varicose veins. The changes that occur in this case in the vessels are usually persistent and irreversible. Varicose veins are more common in women - in 30% of women after 40 and only 10% of men of the same age. (Read also: Varicose veins - causes, symptoms and complications)

Which doctor should I contact with vessels?

Vascular diseases, their conservative and surgical treatment and prevention are dealt with by phlebologists and angiosurgeons. After all the necessary diagnostic procedures, the doctor draws up a course of treatment, which combines conservative methods and surgery. Drug therapy of vascular diseases is aimed at improving blood rheology, lipid metabolism in order to prevent atherosclerosis and other vascular diseases caused by elevated blood cholesterol levels. (See also: High blood cholesterol - what does it mean? What are the causes?) The doctor may prescribe vasodilators, medicines to combat concomitant diseases, such as hypertension. In addition, the patient is prescribed vitamin and mineral complexes, antioxidants.

The course of treatment may include physiotherapy procedures - barotherapy of the lower extremities, magnetic and ozone therapy.

Miraculous remedies that are able to return the vessels to their former shape and elasticity do not exist. It is possible to deal with violations and deviations, first of all, we need good prevention, which includes a whole range of measures. However, if in

The disease is associated with a violation of lipid metabolism. Such a failure provokes the accumulation of so-called “bad” cholesterol in the blood. As a result, "cholesterol plaques" are formed. It is they, deposited on the walls of blood vessels, that carry the main danger. At the site of plaque formation, the vessel becomes fragile, its.

An effective treatment for varicose veins is garlic with oil. In one patient who suffered from severe varicose veins, after a couple of months of using this method of treating varicose veins, the diseased veins left and did not even appear after a difficult summer season! Take white garlic and crush it. Garlic is required with white husks.

The information on the site is intended for familiarization and does not call for self-treatment, a doctor's consultation is required!

Personal blog of Gennady Romat

If we follow the definition, then human blood vessels are flexible, elastic tubes through which the force of a rhythmically contracting heart or pulsating vessel moves blood through the body: to organs and tissues through arteries, arterioles, capillaries, and from them to the heart - through venules and veins, circulating blood flow.

Of course, this is the cardiovascular system. Thanks to blood circulation, oxygen and nutrients are delivered to the organs and tissues of the body, and carbon dioxide and other products of metabolism and vital activity are removed.

Blood and nutrients are delivered through vessels, a kind of "hollow tubes", without which nothing would have happened. Kind of "highways". In fact, our vessels are not "hollow tubes". Of course, they are much more complicated and do their job properly. It depends on the health of the vessels - exactly how, at what speed, under what pressure and to what parts of the body our blood will reach. Human health depends on the state of blood vessels.

This is what a person would look like if only one circulatory system remained from him.. On the right is a human finger, consisting of an incredible number of vessels.

Human blood vessels, interesting facts

The largest vein in the human body is the inferior vena cava. This vessel returns blood from the lower body to the heart.
The human body has both large and small blood vessels. The second is the capillaries. Their diameter does not exceed 8-10 microns. This is so small that the red blood cells have to line up and literally squeeze one by one.
The speed of blood movement through the vessels varies depending on their types and sizes. If the capillaries do not allow the blood to exceed the speed of 0.5 mm / s, then in the inferior vena cava the speed reaches 20 cm / s.
Every second, 25 billion cells pass through the circulatory system. It takes 60 seconds for the blood to make a full circle around the body. It is noteworthy that during the day the blood has to flow through the vessels, overcoming km.
If all the blood vessels were expanded to their full length, they would wrap the planet Earth twice. Their total length is km.
The capacity of all human blood vessels reached. As you know, an adult organism contains on average no more than 6 liters of blood, however, accurate data can only be found by studying the individual characteristics of the organism. As a result, blood has to constantly move through the vessels to keep the muscles and organs working throughout the body.
There is only one place in the human body where there is no circulatory system. This is the cornea of the eye. Since its feature is perfect transparency, it cannot contain vessels. However, it receives oxygen directly from the air.
Since the thickness of the vessels does not exceed 0.5 mm, surgeons use instruments that are even thinner during operations. For example, for suturing, you have to work with a thread that is thinner than a human hair. To cope with it, doctors look through a microscope.
It is estimated that it takes mosquitoes to suck all the blood out of an ordinary adult human.
In a year, your heart beats about 0 times, and for an average life expectancy - about 3 billion, give or take a few million ..
During our lifetime, the heart pumps approximately 150 million liters of blood.

Now we are convinced that our circulatory system is unique, and the heart is the strongest muscle in our body.

At a young age, no one worries about some vessels, and so everything is in order! But after twenty years, after the body has grown, metabolism begins to imperceptibly slow down, motor activity decreases over the years, so the stomach grows, excess weight appears, high blood pressure and cholesterol, atherosclerotic plaques suddenly appear. and you're only fifty years old! What to do?

Moreover, plaques can form anywhere. If in the vessels of the brain, then a stroke is possible. The vessel bursts and everything. If in the aorta, then a heart attack is possible. Smokers usually barely walk by the age of sixty, all have atherosclerosis of the lower extremities.

Look at the statistics of Rosstat, cardiovascular diseases confidently take the first place in terms of the number of deaths.

That is, with your inaction for thirty years, you can clog the vascular system with all sorts of rubbish. Then a natural question arises, but how to pull everything out of there so that the vessels are clean? How to get rid of cholesterol plaques, for example? Well, an iron pipe can be cleaned with a brush, but human vessels are far from being a pipe.

Although, there is such a procedure. Angioplasty is called mechanically drilling or crushing a plaque with a balloon and placing a stent. People love to do such a procedure as plasmapheresis. Yes, a very valuable procedure, but only where it is justified, with strictly defined diseases. To cleanse blood vessels and improve health, it is extremely dangerous to do. Remember the famous Russian athlete, record holder in strength sports, as well as a TV and radio host, showman, actor and entrepreneur, Vladimir Turchinsky, who died after this procedure.

They came up with laser cleaning of blood vessels, that is, a light bulb is inserted into a vein and it glows inside the vessel and does something there. Like as there is a laser evaporation of plaques. It is clear that this procedure is put on a commercial basis. The wiring is complete.

Basically, a person trusts doctors, and therefore pays money to restore his health. At the same time, the majority of people do not want to change anything in their lives. How can you refuse dumplings, sausages, bacon or beer with a cigarette. According to the logic, it turns out that if you have problems with blood vessels, then first you need to remove the damaging factor, for example, quit smoking. If you are overweight, balance your diet, do not overeat at night. Move more. Change your lifestyle. Well, we can't!

No, as usual, we hope for a miracle pill, a miracle procedure, or just a miracle. Miracles happen, but extremely rarely. Well, you paid money, cleaned the vessels, for a while the condition improved, then everything quickly returns to its original state . You do not want to change your lifestyle, and the body will return its own even in excess.

Nikolai Amosov, a well-known Ukrainian, Soviet thoracic surgeon, medical scientist, cybernetician, and writer in the last century, said: “Do not rely on doctors to make you healthy. Doctors treat diseases, but health must be obtained by yourself.”

Nature has endowed us with good, strong vessels - arteries, veins, capillaries, each of which performs its own function. Look at how reliable and cool our circulatory system is, which we sometimes treat very casually. We have two circulations in our body. Large circle and small circle.

Small circle of blood circulation

Systemic circulation

Passed through the pulmonary circulation. (through the lungs) and oxygenated blood returns to the heart. Oxygenated blood from the left atrium passes into the left ventricle, after which it enters the aorta. The aorta is the largest human artery, from which many smaller vessels depart, then the blood is delivered through the arterioles to the organs and returns through the veins back to the right atrium, where the cycle begins anew.

arteries

Oxygenated blood is arterial blood. That's why it's bright red. Arteries are vessels that carry oxygenated blood away from the heart. The arteries have to cope with the high pressure that comes out of the heart. Therefore, there is a very thick muscle layer in the wall of the arteries. Therefore, the arteries practically cannot change their lumen. They are not very good at contracting and relaxing. but they hold the beats of the heart very well. Arteries resist pressure. that creates the heart.

The structure of the wall of the artery The structure of the wall of the vein

Arteries are made up of three layers. The inner layer of the artery is a thin layer of integumentary tissue - the epithelium. Then comes a thin layer of connective tissue, (not visible in the figure) elastic like rubber. Next comes a thick layer of muscles and an outer shell.

Purpose of the arteries or functions of the arteries

Arteries carry oxygenated blood. flows from the heart to the organs.
Functions of the arteries. is the delivery of blood to organs. providing high pressure.
Oxygenated blood flows in the arteries (except the pulmonary artery).
Blood pressure in the arteries - 120 ⁄ 80 mm. rt. Art.
The speed of blood movement in the arteries is 0.5 m.⁄ sec.
arterial pulse. This is the rhythmic oscillation of the walls of the arteries during the systole of the ventricles of the heart.
Maximum pressure - during heart contraction (systole)
Minimum during relaxation (diastole)

Veins - structure and functions

The layers of a vein are exactly the same as those of an artery. The epithelium is the same everywhere, in all vessels. But at the vein, relative to the artery, there is a very thin layer of muscle tissue. Muscles in a vein are needed not so much to resist blood pressure, but to contract and expand. The vein shrinks, the pressure increases and vice versa.

Therefore, in their structure, the veins are quite close to the arteries, but, with their own characteristics, for example, in the veins there is already low pressure and a low speed of blood flow. These features give some features to the walls of the veins. Compared to arteries, veins are large in diameter, have a thin inner wall and a well-defined outer wall. Due to its structure, the venous system contains about 70% of the total blood volume.

Another feature of the veins is that valves constantly go in the veins. approximately the same as at the exit from the heart. This is necessary so that the blood does not flow in the opposite direction, but is pushed forward.

The valves open as the blood flows. When the vein fills with blood, the valve closes, making it impossible for blood to flow back. The most developed valve apparatus is near the veins, in the lower part of the body.

Everything is simple, blood returns easily from the head to the heart, since gravity acts on it, but it is much more difficult for it to rise from the legs. you have to overcome this force of gravity. The valve system helps push blood back to the heart.

Valves. this is good, but it is clearly not enough to push the blood back to the heart. There is another strength. The fact is that veins, unlike arteries, run along muscle fibers. and when the muscle contracts it compresses the vein. In theory, blood should go in both directions, but there are valves that prevent blood from flowing in the opposite direction, only forward to the heart. Thus, the muscle pushes blood to the next valve. This is important because the lower outflow of blood occurs mainly due to the muscles. And if your muscles have long been weak from idleness? Has hypodynamia crept imperceptibly? What will happen? It is clear that nothing good.

The movement of blood through the veins occurs against the force of gravity, in connection with this, the venous blood experiences the force of hydrostatic pressure. Sometimes, when the valves fail, gravity is so strong that it interferes with normal blood flow. In this case, the blood stagnates in the vessels and deforms them. After that, the veins are called varicose veins.

Varicose veins have a swollen appearance, which is justified by the name of the disease (from Latin varix, genus varicis - “bloating”). The treatments for varicose veins today are very extensive, from popular advice to sleep in such a position that the feet are above the level of the heart to surgery and removal of the vein.

Another disease is venous thrombosis. Thrombosis causes blood clots (thrombi) to form in the veins. This is a very dangerous disease, because. blood clots, breaking away, can move through the circulatory system to the vessels of the lung. If the clot is large enough, it can be fatal if it enters the lungs.

Vienna. vessels that carry blood to the heart.
The walls of the veins are thin, easily extensible, and are not able to contract on their own.
A feature of the structure of the veins is the presence of pocket-like valves.
Veins are divided into large (vena cava), medium veins and small venules.
Blood saturated with carbon dioxide moves through the veins (except the pulmonary vein)
Blood pressure in veins. rt. Art.
The speed of blood movement in the veins is 0.06 - 0.2 m.sec.
Veins lie superficially, unlike arteries.

capillaries

The capillary is the thinnest vessel in the human body. Capillaries are the smallest blood vessels 50 times thinner than a human hair. The average capillary diameter is 5-10 µm. Connecting arteries and veins, it is involved in the metabolism between blood and tissues.

The capillary walls are composed of a single layer of endothelial cells. The thickness of this layer is so small that it allows the exchange of substances between tissue fluid and blood plasma through the walls of the capillaries. Bodily products (such as carbon dioxide and urea) can also pass through the walls of the capillaries to be transported to the site of excretion from the body.

Endothelium

It is through the walls of the capillaries that nutrients enter our muscles and tissues, saturating them with oxygen as well. It should be noted that not all substances pass through the walls of the endothelium, but only those that are necessary for the body. For example, oxygen passes through, but other impurities do not. This is called endothelial permeability. It is the same with food. . Without this function, we would have been poisoned long ago.

The vascular wall endothelium is the thinnest organ that performs a number of important functions. The endothelium, if necessary, releases a substance to force platelets to stick together and repair, for example, a cut. But so that platelets do not stick together just like that, the endothelium secretes a substance that prevents our platelets from sticking together and forming blood clots. Entire institutes are working on the study of the endothelium in order to fully understand this amazing organ.

Another function is angiogenesis - the endothelium causes small vessels to grow, bypassing the clogged ones. For example, bypassing the cholesterol plaque.

Fight against vascular inflammation. This is also a function of the endothelium. Atherosclerosis. it is a kind of inflammation of the blood vessels. To date, they are even beginning to treat atherosclerosis with antibiotics.

Regulation of vascular tone. This is also done by the endothelium. Nicotine has a very detrimental effect on the endothelium. Vasospasm immediately occurs, or rather endothelial paralysis, which causes nicotine, and combustion products contained in nicotine. There are approximately 700 of these products.

The endothelium must be strong and elastic. like all our vessels. Atherosclerosis occurs when a particular person begins to move little, eat improperly and, accordingly, release few of their own hormones into the blood.

You can clean the vessels only by physical activity. If you regularly release hormones into the blood, they will heal the walls of the vessels, there will be no holes and there will be nowhere for cholesterol plaques to form. Eat right. control your sugar and cholesterol levels. Folk remedies can be used as an addition, the basis is still physical activity. For example, the health-improving system -isotone, was just invented for the recovery of anyone who wishes.

About human vessels: 3 comments

And my husband smokes and laughs at it all! Believe in nothing! He says .- Churchill smoked and lived up to 90 years, and smoking does not affect blood vessels!

Health to your husband! Do you think that Churchill did not have atherosclerosis? Surely there was! Well, he's lucky! All of this is about one particular person. So far, your husband is doing relatively well, problems begin at an older age, flying in, and for some even before 40 years old. What can I say, he likes to smoke, well, let him smoke for the time being. My father-in-law smoked from the age of 14 and quit at the age of 80, simply, without any anti-nicotine pills, patches, etc. There was a micro stroke. Now he is 85 years old, does gymnastics, walks, but years of smoking affect his legs.

Physical activity does not always help and this is a fact, it all depends on the body.

Diagram of the human cardiovascular system

The most important task of the cardiovascular system is to provide tissues and organs with nutrients and oxygen, as well as to remove the products of cell metabolism (carbon dioxide, urea, creatinine, bilirubin, uric acid, ammonia, etc.). Enrichment with oxygen and removal of carbon dioxide occurs in the capillaries of the pulmonary circulation, and saturation with nutrients in the vessels of the systemic circulation during the passage of blood through the capillaries of the intestine, liver, adipose tissue and skeletal muscles.

The human circulatory system consists of the heart and blood vessels. Their main function is to ensure the movement of blood, carried out thanks to the work on the principle of a pump. With the contraction of the ventricles of the heart (during their systole), blood is expelled from the left ventricle into the aorta, and from the right ventricle into the pulmonary trunk, from which, respectively, the large and small circles of blood circulation (BCC and ICC) begin. The large circle ends with the inferior and superior vena cava, through which venous blood returns to the right atrium. And the small circle is represented by four pulmonary veins, through which arterial, oxygenated blood flows to the left atrium.

Based on the description, arterial blood flows through the pulmonary veins, which does not correspond to everyday ideas about the human circulatory system (it is believed that venous blood flows through the veins, and arterial blood flows through the arteries).

After passing through the cavity of the left atrium and ventricle, the blood with nutrients and oxygen enters the capillaries of the BCC through the arteries, where it exchanges oxygen and carbon dioxide between it and the cells, delivers nutrients and removes metabolic products. The latter with the blood flow reach the excretory organs (kidneys, lungs, glands of the gastrointestinal tract, skin) and are excreted from the body.

BPC and ICC are connected sequentially. The movement of blood in them can be demonstrated using the following scheme: right ventricle → pulmonary trunk → small circle vessels → pulmonary veins → left atrium → left ventricle → aorta → large circle vessels → inferior and superior vena cava → right atrium → right ventricle.

Depending on the function performed and the structural features of the vascular wall, the vessels are divided into the following:

1. Shock-absorbing (vessels of the compression chamber) - aorta, pulmonary trunk and large arteries of the elastic type. They smooth out periodic systolic waves of blood flow: soften the hydrodynamic shock of blood ejected by the heart during systole, and ensure the movement of blood to the periphery during diastole of the ventricles of the heart.
2. Resistive (vessels of resistance) - small arteries, arterioles, metarterioles. Their walls contain a huge number of smooth muscle cells, thanks to the contraction and relaxation of which they can quickly change the size of their lumen. Providing variable resistance to blood flow, resistive vessels maintain blood pressure (BP), regulate the amount of organ blood flow and hydrostatic pressure in the vessels of the microvasculature (MCR).
3. Exchange - ICR vessels. Through the wall of these vessels there is an exchange of organic and inorganic substances, water, gases between blood and tissues. The blood flow in the MCR vessels is regulated by arterioles, venules and pericytes - smooth muscle cells located outside the precapillaries.
4. Capacitive - veins. These vessels are highly extensible, due to which they can deposit up to 60–75% of the circulating blood volume (CBV), regulating the return of venous blood to the heart. The veins of the liver, skin, lungs and spleen have the most depositing properties.
5. Shunting - arteriovenous anastomoses. When they open, arterial blood is discharged along the pressure gradient into the veins, bypassing the ICR vessels. For example, this happens when the skin is cooled, when the blood flow is directed through arteriovenous anastomoses to reduce heat loss, bypassing the skin capillaries. At the same time, the skin turns pale.

The ICC serves to oxygenate the blood and remove carbon dioxide from the lungs. After the blood has entered the pulmonary trunk from the right ventricle, it is sent to the left and right pulmonary arteries. The latter are a continuation of the pulmonary trunk. Each pulmonary artery, passing through the gates of the lung, branches into smaller arteries. The latter, in turn, pass into the ICR (arterioles, precapillaries and capillaries). In the ICR, venous blood is converted into arterial blood. The latter enters from the capillaries into venules and veins, which, merging into 4 pulmonary veins (2 from each lung), flow into the left atrium.

BPC serves to deliver nutrients and oxygen to all organs and tissues and remove carbon dioxide and metabolic products. After the blood has entered the aorta from the left ventricle, it is directed to the aortic arch. Three branches depart from the latter (brachiocephalic trunk, common carotid and left subclavian arteries), which supply blood to the upper limbs, head and neck.

After that, the aortic arch passes into the descending aorta (thoracic and abdominal). The latter at the level of the fourth lumbar vertebra is divided into common iliac arteries, which supply blood to the lower limbs and pelvic organs. These vessels are divided into external and internal iliac arteries. The external iliac artery passes into the femoral artery, supplying arterial blood to the lower extremities below the inguinal ligament.

All arteries, heading to tissues and organs, in their thickness pass into arterioles and further into capillaries. In the ICR, arterial blood is converted into venous blood. Capillaries pass into venules and then into veins. All veins accompany arteries and are named similarly to arteries, but there are exceptions (portal vein and jugular veins). Approaching the heart, the veins merge into two vessels - the inferior and superior vena cava, which flow into the right atrium.

Sometimes a third circle of blood circulation is isolated - cardiac, which serves the heart itself.

Arterial blood is indicated in black in the picture, and venous blood is indicated in white. 1. Common carotid artery. 2. Aortic arch. 3. Pulmonary arteries. 4. Aortic arch. 5. Left ventricle of the heart. 6. Right ventricle of the heart. 7. Celiac trunk. 8. Superior mesenteric artery. 9. Inferior mesenteric artery. 10. Inferior vena cava. 11. Bifurcation of the aorta. 12. Common iliac arteries. 13. Vessels of the pelvis. 14. Femoral artery. 15. Femoral vein. 16. Common iliac veins. 17. Portal vein. 18. Hepatic veins. 19. Subclavian artery. 20. Subclavian vein. 21. Superior vena cava. 22. Internal jugular vein.

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Human blood vessels. How are arteries different from veins in humans?

The distribution of blood throughout the human body is carried out due to the work of the cardiovascular system. Its main organ is the heart. Each of his blows contributes to the fact that the blood moves and nourishes all organs and tissues.

System Structure

There are different types of blood vessels in the body. Each of them has its own purpose. So, the system includes arteries, veins and lymphatic vessels. The first of them are designed to ensure that blood enriched with nutrients enters the tissues and organs. It is saturated with carbon dioxide and various products released during the life of cells, and returns through the veins back to the heart. But before entering this muscular organ, the blood is filtered in the lymphatic vessels.

The total length of the system, consisting of blood and lymphatic vessels, in the body of an adult is about 100 thousand km. And the heart is responsible for its normal functioning. It is it that pumps about 9.5 thousand liters of blood every day.

Principle of operation

The circulatory system is designed to support the entire body. If there are no problems, then it functions as follows. Oxygenated blood exits the left side of the heart through the largest arteries. It spreads throughout the body to all cells through wide vessels and the smallest capillaries, which can only be seen under a microscope. It is the blood that enters the tissues and organs.

The place where the arterial and venous systems connect is called the capillary bed. The walls of the blood vessels in it are thin, and they themselves are very small. This allows you to fully release oxygen and various nutrients through them. The waste blood enters the veins and returns through them to the right side of the heart. From there, it enters the lungs, where it is enriched again with oxygen. Passing through the lymphatic system, the blood is cleansed.

Veins are divided into superficial and deep. The first are close to the surface of the skin. Through them, blood enters the deep veins, which return it to the heart.

The regulation of blood vessels, heart function and general blood flow is carried out by the central nervous system and local chemicals released in the tissues. This helps control the flow of blood through the arteries and veins, increasing or decreasing its intensity depending on the processes taking place in the body. For example, it increases with physical exertion and decreases with injuries.

How does blood flow

The spent "depleted" blood through the veins enters the right atrium, from where it flows into the right ventricle of the heart. With powerful movements, this muscle pushes the incoming fluid into the pulmonary trunk. It is divided into two parts. The blood vessels of the lungs are designed to enrich the blood with oxygen and return them to the left ventricle of the heart. Each person has this part of him more developed. After all, it is the left ventricle that is responsible for how the entire body will be supplied with blood. It is estimated that the load that falls on it is 6 times greater than that to which the right ventricle is subjected.

The circulatory system includes two circles: small and large. The first of them is designed to saturate the blood with oxygen, and the second - for its transportation throughout the orgasm, delivery to every cell.

Requirements for the circulatory system

In order for the human body to function normally, a number of conditions must be met. First of all, attention is paid to the state of the heart muscle. After all, it is she who is the pump that drives the necessary biological fluid through the arteries. If the work of the heart and blood vessels is impaired, the muscle is weakened, then this can cause peripheral edema.

It is important that the difference between the areas of low and high pressure is observed. It is necessary for normal blood flow. So, for example, in the region of the heart, the pressure is lower than at the level of the capillary bed. This allows you to comply with the laws of physics. Blood moves from an area of higher pressure to an area where it is lower. If a number of diseases occur, due to which the established balance is disturbed, then this is fraught with congestion in the veins, swelling.

The ejection of blood from the lower extremities is carried out thanks to the so-called musculo-venous pumps. This is what the calf muscles are called. With each step, they contract and push the blood against the natural force of gravity towards the right atrium. If this function is disturbed, for example, as a result of an injury and temporary immobilization of the legs, then edema occurs due to a decrease in venous return.

Another important link responsible for ensuring that the human blood vessels function normally are venous valves. They are designed to support the fluid flowing through them until it enters the right atrium. If this mechanism is disturbed, and this is possible as a result of injuries or due to valve wear, abnormal blood collection will be observed. As a result, this leads to an increase in pressure in the veins and squeezing out the liquid part of the blood into the surrounding tissues. A striking example of a violation of this function is varicose veins in the legs.

Vessel classification

To understand how the circulatory system works, it is necessary to understand how each of its components functions. So, the pulmonary and hollow veins, the pulmonary trunk and the aorta are the main ways of moving the necessary biological fluid. And all the rest are able to regulate the intensity of the inflow and outflow of blood to the tissues due to the ability to change their lumen.

All vessels in the body are divided into arteries, arterioles, capillaries, venules, veins. All of them form a closed connecting system and serve a single purpose. Moreover, each blood vessel has its own purpose.

arteries

The areas through which blood moves are divided depending on the direction in which it moves in them. So, all arteries are designed to carry blood from the heart throughout the body. They are elastic, muscular and muscular-elastic type.

The first type includes those vessels that are directly connected with the heart and exit from its ventricles. This is the pulmonary trunk, pulmonary and carotid arteries, aorta.

All of these vessels of the circulatory system consist of elastic fibers that are stretched. This happens with every heartbeat. As soon as the contraction of the ventricle has passed, the walls return to their original form. Due to this, normal pressure is maintained for a period until the heart fills with blood again.

Blood enters all tissues of the body through the arteries that depart from the aorta and pulmonary trunk. At the same time, different organs need different amounts of blood. This means that the arteries must be able to narrow or expand their lumen so that the fluid passes through them only in the required doses. This is achieved due to the fact that smooth muscle cells work in them. Such human blood vessels are called distributive. Their lumen is regulated by the sympathetic nervous system. The muscular arteries include the artery of the brain, radial, brachial, popliteal, vertebral and others.

Other types of blood vessels are also isolated. These include muscular-elastic or mixed arteries. They can contract very well, but at the same time they have high elasticity. This type includes the subclavian, femoral, iliac, mesenteric arteries, celiac trunk. They contain both elastic fibers and muscle cells.

Arterioles and capillaries

As blood moves along the arteries, their lumen decreases and the walls become thinner. Gradually they pass into the smallest capillaries. The area where arteries end is called arterioles. Their walls consist of three layers, but they are weakly expressed.

The thinnest vessels are the capillaries. Together, they represent the longest part of the entire circulatory system. It is they who connect the venous and arterial channels.

A true capillary is a blood vessel that is formed as a result of branching of arterioles. They can form loops, networks that are located in the skin or synovial bags, or vascular glomeruli that are located in the kidneys. The size of their lumen, the speed of blood flow in them and the shape of the networks formed depend on the tissues and organs in which they are located. So, for example, the thinnest vessels are located in skeletal muscles, lungs and nerve sheaths - their thickness does not exceed 6 microns. They form only flat networks. In mucous membranes and skin, they can reach 11 microns. In them, the vessels form a three-dimensional network. The widest capillaries are found in the hematopoietic organs, endocrine glands. Their diameter in them reaches 30 microns.

The density of their placement is also not the same. The highest concentration of capillaries is noted in the myocardium and brain, for every 1 mm 3 there are up to 3,000 of them. At the same time, there are only up to 1000 of them in the skeletal muscle, and even less in the bone tissue. It is also important to know that in an active state, under normal conditions, blood does not circulate in all capillaries. About 50% of them are in an inactive state, their lumen is compressed to a minimum, only plasma passes through them.

Venules and veins

Capillaries, which receive blood from arterioles, unite and form larger vessels. They are called postcapillary venules. The diameter of each such vessel does not exceed 30 µm. Folds form at the transition points, which perform the same functions as the valves in the veins. Elements of blood and plasma can pass through their walls. Postcapillary venules unite and flow into collecting venules. Their thickness is up to 50 microns. Smooth muscle cells begin to appear in their walls, but often they do not even surround the lumen of the vessel, but their outer shell is already clearly defined. The collecting venules become muscle venules. The diameter of the latter often reaches 100 microns. They already have up to 2 layers of muscle cells.

The circulatory system is designed in such a way that the number of vessels that drain blood is usually twice the number of those through which it enters the capillary bed. In this case, the liquid is distributed as follows. Up to 15% of the total amount of blood in the body is in the arteries, up to 12% in the capillaries, and 70-80% in the venous system.

By the way, fluid can flow from arterioles to venules without entering the capillary bed through special anastomoses, the walls of which include muscle cells. They are found in almost all organs and are designed to ensure that blood can be discharged into the venous bed. With their help, pressure is controlled, the transition of tissue fluid and blood flow through the organ is regulated.

Veins are formed after the confluence of venules. Their structure directly depends on the location and diameter. The number of muscle cells is affected by the place of their localization and the factors under the influence of which fluid moves in them. Veins are divided into muscular and fibrous. The latter include the vessels of the retina, spleen, bones, placenta, soft and hard shells of the brain. The blood circulating in the upper part of the body moves mainly under the force of gravity, as well as under the influence of the suction action during inhalation of the chest cavity.

The veins of the lower extremities are different. Each blood vessel in the legs must resist the pressure that is created by the fluid column. And if the deep veins are able to maintain their structure due to the pressure of the surrounding muscles, then the superficial ones have a harder time. They have a well-developed muscle layer, and their walls are much thicker.

Also, a characteristic difference between the veins is the presence of valves that prevent the backflow of blood under the influence of gravity. True, they are not in those vessels that are in the head, brain, neck and internal organs. They are also absent in the hollow and small veins.

The functions of blood vessels differ depending on their purpose. So, veins, for example, serve not only to move fluid to the region of the heart. They are also designed to reserve it in separate areas. The veins are activated when the body is working hard and needs to increase the volume of circulating blood.

The structure of the walls of the arteries

Each blood vessel is made up of several layers. Their thickness and density depend solely on what type of veins or arteries they belong to. It also affects their composition.

So, for example, elastic arteries contain a large number of fibers that provide stretching and elasticity of the walls. The inner shell of each such blood vessel, which is called the intima, is about 20% of the total thickness. It is lined with endothelium, and under it is loose connective tissue, intercellular substance, macrophages, muscle cells. The outer layer of the intima is limited by an internal elastic membrane.

The middle layer of such arteries consists of elastic membranes, with age they thicken, their number increases. Between them are smooth muscle cells that produce intercellular substance, collagen, elastin.

The outer shell of the elastic arteries is formed by fibrous and loose connective tissue, elastic and collagen fibers are located longitudinally in it. It also contains small vessels and nerve trunks. They are responsible for the nutrition of the outer and middle shells. It is the outer part that protects the arteries from ruptures and overstretching.

The structure of blood vessels, which are called muscular arteries, is not much different. They also have three layers. The inner shell is lined with endothelium, it contains the inner membrane and loose connective tissue. In small arteries, this layer is poorly developed. The connective tissue contains elastic and collagen fibers, they are located longitudinally in it.

The middle layer is formed by smooth muscle cells. They are responsible for the contraction of the entire vessel and for pushing blood into the capillaries. Smooth muscle cells are connected to the intercellular substance and elastic fibers. The layer is surrounded by a kind of elastic membrane. The fibers located in the muscle layer are connected to the outer and inner shells of the layer. They seem to form an elastic frame that prevents the artery from sticking together. And muscle cells are responsible for regulating the thickness of the lumen of the vessel.

The outer layer consists of loose connective tissue, in which collagen and elastic fibers are located, they are located obliquely and longitudinally in it. Nerves, lymphatic and blood vessels pass through it.

The structure of mixed-type blood vessels is an intermediate link between muscular and elastic arteries.

Arterioles also consist of three layers. But they are rather weakly expressed. The inner shell is the endothelium, a layer of connective tissue and an elastic membrane. The middle layer consists of 1 or 2 layers of muscle cells that are arranged in a spiral.

The structure of the veins

In order for the heart and blood vessels called arteries to function, it is necessary that blood can rise back up, bypassing the force of gravity. For these purposes, venules and veins, which have a special structure, are intended. These vessels consist of three layers, as well as arteries, although they are much thinner.

The inner shell of the veins contains endothelium, it also has a poorly developed elastic membrane and connective tissue. The middle layer is muscular, it is poorly developed, there are practically no elastic fibers in it. By the way, precisely because of this, the cut vein always subsides. The outer shell is the thickest. It consists of connective tissue, it contains a large number of collagen cells. It also contains smooth muscle cells in some veins. They help push blood towards the heart and prevent its reverse flow. The outer layer also contains lymph capillaries.

Structure and functions of the vascular wall

Blood in the human body flows through a closed system of blood vessels. Vessels not only passively limit the volume of circulation and mechanically prevent blood loss, but also have a whole range of active functions in hemostasis. Under physiological conditions, an intact vascular wall helps to maintain the liquid state of the blood. Intact endothelium in contact with blood does not have the ability to initiate the clotting process. In addition, it contains on its surface and releases into the bloodstream substances that prevent clotting. This property prevents thrombus formation on intact endothelium and limits thrombus growth beyond the injury. When damaged or inflamed, the vessel wall takes part in the formation of a thrombus. First, subendothelial structures that come into contact with blood only in case of damage or the development of a pathological process have a powerful thrombogenic potential. Secondly, the endothelium in the damaged area is activated and it appears

procoagulant properties. The structure of the vessels is shown in Fig. 2.

The vascular wall of all vessels, except for pre-capillaries, capillaries and post-capillaries, consists of three layers: the inner shell (intima), the middle shell (media) and the outer shell (adventitia).

Intima. Throughout the bloodstream under physiological conditions, the blood is in contact with the endothelium, which forms the inner layer of the intima. The endothelium, which consists of a monolayer of endothelial cells, plays the most active role in hemostasis. The properties of the endothelium differ somewhat in different parts of the circulatory system, determining the different hemostatic status of arteries, veins, and capillaries. Under the endothelium is an amorphous intercellular substance with smooth muscle cells, fibroblasts and macrophages. Also there are inclusions of lipids in the form of drops, more often located extracellularly. At the border of the intima and the media is the inner elastic membrane.

Rice. 2. The vascular wall consists of intima, the luminal surface of which is covered with a single-layer endothelium, media (smooth muscle cells) and adventitia (connective tissue frame): A - large muscular-elastic artery (schematic representation), B - arterioles (histological preparation), C - coronary artery in cross section

Media consists of smooth muscle cells and intercellular substance. Its thickness varies significantly in different vessels, causing their different ability to contract, strength and elasticity.

Adventitia It is made up of connective tissue containing collagen and elastin.

Arterioles (arterial vessels with a total diameter of less than 100 microns) are transitional vessels from arteries to capillaries. The wall thickness of the arterioles is slightly less than the width of their lumen. The vascular wall of the largest arterioles consists of three layers. As the arterioles branch, their walls become thinner and the lumen narrower, but the ratio of lumen width to wall thickness remains the same. In the smallest arterioles, one or two layers of smooth muscle cells, endotheliocytes, and a thin outer shell consisting of collagen fibers are visible on a transverse section.

Capillaries consist of a monolayer of endotheliocytes surrounded by a basal plate. In addition, in the capillaries around endotheliocytes, another type of cells is found - pericytes, the role of which has not been studied enough.

The capillaries open at their venous end into postcapillary venules (diameter 8–30 µm), which are characterized by an increase in the number of pericytes in the vascular wall. Postcapillary venules, in turn, flow into

collecting venules (diameter) whose wall, in addition to pericytes, has an outer shell consisting of fibroblasts and collagen fibers. The collecting venules drain into muscle venules, which have one or two layers of smooth muscle fibers in the media. In general, venules consist of an endothelial lining, a basement membrane directly adjacent to the outside of endotheliocytes, pericytes, also surrounded by a basement membrane; outside of the basement membrane there is a layer of collagen. The veins are equipped with valves that are oriented in such a way as to allow blood to flow towards the heart. Most of the valves are in the veins of the extremities, and they are absent in the veins of the chest and abdominal organs.

Function of vessels in hemostasis:

Mechanical restriction of blood flow.

Regulation of blood flow through the vessels, including

le spastic reaction of damaged

Regulation of hemostatic reactions by

synthesis and representation on the surface en

dothelium and in the subendothelial layer of proteins,

peptides and non-protein substances, directly

directly involved in hemostasis.

Representation on the cell surface

tori for enzymatic complexes,

treated in coagulation and fibrinolysis.

Characterization of the enlotelial cover

The vascular wall has an active surface lined with endothelial cells on the inside. The integrity of the endothelial cover is the basis for the normal functioning of blood vessels. The surface area of the endothelial cover in the vessels of an adult is comparable to the area of a football field. The cell membrane of endotheliocytes has a high fluidity, which is an important condition for the antithrombogenic properties of the vascular wall. High fluidity provides a smooth inner surface of the endothelium (Fig. 3), which functions as an integral layer and excludes the contact of blood plasma pro-coagulants with subendothelial structures.

Endotheliocytes synthesize, present on their surface and release into the blood and subendothelial space a whole range of biologically active substances. These are proteins, peptides and non-protein substances that regulate hemostasis. In table. 1 lists the main products of endotheliocytes involved in hemostasis.

2. Types of blood vessels, features of their structure and function.

3. The structure of the heart.

4. Topography of the heart.

1. General characteristics of the cardiovascular system and its significance.

The cardiovascular system includes two systems: the circulatory (circulatory system) and the lymphatic (lymphatic circulation system). The circulatory system combines the heart and blood vessels. The lymphatic system includes lymphatic capillaries branched in organs and tissues, lymphatic vessels, lymphatic trunks and lymphatic ducts, through which lymph flows towards large venous vessels. The doctrine of the cardiovascular system is called angiocardiology.

The circulatory system is one of the main systems of the body. It ensures the delivery of nutrients, regulatory, protective substances, oxygen to tissues, the removal of metabolic products, and heat transfer. It is a closed vascular network penetrating all organs and tissues, and having a centrally located pumping device - the heart.

Types of blood vessels, features of their structure and function.

Anatomically, blood vessels are divided into arteries, arterioles, precapillaries, capillaries, postcapillaries, venules and veins.

Arteries are blood vessels that carry blood from the heart, regardless of whether they contain arterial or venous blood. They are a cylindrical tube, the walls of which consist of 3 shells: outer, middle and inner. The outer (adventitial) membrane is represented by connective tissue, the middle one is smooth muscle, and the inner one is endothelial (intima). In addition to the endothelial lining, the inner lining of most arteries also has an internal elastic membrane. The outer elastic membrane is located between the outer and middle shells. Elastic membranes give the walls of the arteries additional strength and elasticity. The thinnest arterial vessels are called arterioles. They pass into precapillaries, and the latter into capillaries, the walls of which are highly permeable, due to which there is an exchange of substances between blood and tissues.

Capillaries are microscopic vessels that are found in tissues and connect arterioles to venules through precapillaries and postcapillaries. Postcapillaries are formed from the fusion of two or more capillaries. As the postcapillaries merge, venules are formed - the smallest venous vessels. They flow into the veins.

Veins are blood vessels that carry blood to the heart. The walls of the veins are much thinner and weaker than the arterial ones, but they consist of the same three membranes. However, the elastic and muscular elements in the veins are less developed, so the walls of the veins are more pliable and may collapse. Unlike arteries, many veins have valves. The valves are semi-lunar folds of the inner shell that prevent the reverse flow of blood into them. There are especially many valves in the veins of the lower extremities, in which the movement of blood occurs against gravity and creates the possibility of stagnation and reverse blood flow. There are many valves in the veins of the upper extremities, less in the veins of the trunk and neck. Only both vena cava, veins of the head, renal veins, portal and pulmonary veins do not have valves.

Branchings of the arteries are interconnected, forming arterial fistulas - anastomoses. The same anastomoses connect the veins. In violation of the inflow or outflow of blood through the main vessels, anastomoses contribute to the movement of blood in various directions. Vessels that provide blood flow bypassing the main path are called collateral (roundabout).

The blood vessels of the body are combined into a large and small circles of blood circulation. In addition, the coronary circulation is additionally isolated.

The systemic circulation (corporeal) begins from the left ventricle of the heart, from which blood enters the aorta. From the aorta through the system of arteries, blood is carried away into the capillaries of the organs and tissues of the whole body. Through the walls of the capillaries of the body there is an exchange of substances between the blood and tissues. Arterial blood gives oxygen to the tissues and, saturated with carbon dioxide, turns into venous blood. The systemic circulation ends with two vena cava, which flow into the right atrium.

The pulmonary circulation (pulmonary) begins with the pulmonary trunk, which departs from the right ventricle. It carries blood to the pulmonary capillary system. In the capillaries of the lungs, venous blood, enriched with oxygen and freed from carbon dioxide, turns into arterial blood. From the lungs, arterial blood flows through 4 pulmonary veins into the left atrium. This is where the pulmonary circulation ends.

Thus, blood moves through a closed circulatory system. The speed of blood circulation in a large circle is 22 seconds, in a small one - 5 seconds.

The coronary circulation (cardiac) includes the vessels of the heart itself for the blood supply to the heart muscle. It begins with the left and right coronary arteries, which depart from the initial section of the aorta - the aortic bulb. Flowing through the capillaries, the blood gives oxygen and nutrients to the heart muscle, receives decay products, and turns into venous blood. Almost all veins of the heart flow into a common venous vessel - the coronary sinus, which opens into the right atrium.

Heart (cor; Greek cardia) - a hollow muscular organ, shaped like a cone, the top of which is turned down, left and forward, and the base is up, right and back. The heart is located in the chest cavity between the lungs, behind the sternum, in the region of the anterior mediastinum. Approximately 2/3 of the heart is in the left side of the chest and 1/3 in the right.

The heart has 3 surfaces. The anterior surface of the heart is adjacent to the sternum and costal cartilages, the posterior surface is adjacent to the esophagus and the thoracic part of the aorta, and the lower surface is adjacent to the diaphragm.

On the heart, edges (right and left) and grooves are also distinguished: coronal and 2 interventricular (anterior and posterior). The coronal sulcus separates the atria from the ventricles, and the interventricular sulci separate the ventricles. The grooves contain blood vessels and nerves.

The size of the heart varies from person to person. Usually, the size of the heart is compared with the size of the fist of a given person (length cm, transverse size - 9-11 cm, anteroposterior size - 6-8 cm). The mass of the heart of an adult is on average g.

The wall of the heart consists of 3 layers:

The inner layer (endocardium) lines the cavity of the heart from the inside, its outgrowths form the valves of the heart. It consists of a layer of flattened, thin, smooth endothelial cells. The endocardium forms the atrioventricular valves, the valves of the aorta, the pulmonary trunk, as well as the valves of the inferior vena cava and coronary sinus;

The middle layer (myocardium) is the contractile apparatus of the heart. The myocardium is formed by striated cardiac muscle tissue and is the thickest and functionally most powerful part of the heart wall. The thickness of the myocardium is not the same: the largest is in the left ventricle, the smallest is in the atria.

The myocardium of the ventricles consists of three muscle layers - outer, middle and inner; atrial myocardium - from two layers of muscles - superficial and deep. The muscle fibers of the atria and ventricles originate from the fibrous rings that separate the atria from the ventricles. fibrous rings are located around the right and left atrioventricular openings and form a kind of skeleton of the heart, which includes thin rings of connective tissue around the openings of the aorta, pulmonary trunk and adjacent right and left fibrous triangles.

The outer layer (epicardium) covers the outer surface of the heart and the areas of the aorta, pulmonary trunk and vena cava closest to the heart. It is formed by a layer of cells of the epithelial type and is the inner sheet of the pericardial serous membrane - the pericardium. The pericardium isolates the heart from surrounding organs, prevents the heart from overstretching, and the fluid between its plates reduces friction during heart contractions.

The human heart is divided by a longitudinal partition into 2 halves (right and left) that do not communicate with each other. In the upper part of each half is the atrium (atrium) right and left, in the lower part - the ventricle (ventriculus) right and left. Thus, the human heart has 4 chambers: 2 atria and 2 ventricles.

The right atrium receives blood from all parts of the body through the superior and inferior vena cava. 4 pulmonary veins flow into the left atrium, carrying arterial blood from the lungs. From the right ventricle, the pulmonary trunk exits, through which venous blood enters the lungs. The aorta emerges from the left ventricle, carrying arterial blood to the vessels of the systemic circulation.

Each atrium communicates with the corresponding ventricle through an atrioventricular orifice equipped with a cusp valve. The valve between the left atrium and ventricle is bicuspid (mitral), between the right atrium and ventricle - tricuspid. The valves open towards the ventricles and allow blood to flow only in that direction.

The pulmonary trunk and aorta at their beginning have semilunar valves, consisting of three semilunar valves and opening in the direction of blood flow in these vessels. Special protrusions of the atria form the right and left auricles of the atria. On the inner surface of the right and left ventricles there are papillary muscles - these are outgrowths of the myocardium.

The upper border corresponds to the upper edge of the cartilages of the third pair of ribs.

The left border runs along an arcuate line from the cartilage of the third rib to the projection of the apex of the heart.

The apex of the heart is determined in the left 5th intercostal space 1–2 cm medially to the left midclavicular line.

The right border runs 2 cm to the right of the right edge of the sternum

The lower border is from the upper edge of the cartilage of the V right rib to the projection of the apex of the heart.

There are age, constitutional features of the location (in newborns, the heart lies entirely in the left half of the chest horizontally).

The main hemodynamic indicators are the volumetric blood flow velocity, pressure in various parts of the vascular bed.

Volumetric velocity is the amount of blood flowing through the cross section of the vessel per unit time and depends on the pressure difference at the beginning and end of the vascular system and on the resistance.

Blood pressure depends on the work of the heart. Blood pressure fluctuates in the vessels with each systole and diastole. During systole, blood pressure rises - systolic pressure. At the end of diastole, the diastolic decreases. The difference between systolic and diastolic characterizes the pulse pressure.

Blood vessels are the most important part of the body, which is part of the circulatory system and permeates almost the entire human body. They are absent only in the skin, hair, nails, cartilage and cornea of the eyes. And if they are assembled and stretched into one straight line, then the total length will be about 100 thousand km.

These tubular elastic formations function continuously, transferring blood from the constantly contracting heart to all corners of the human body, saturating them with oxygen and nourishing them, and then returning it back. By the way, the heart pushes more than 150 million liters of blood through the vessels in a lifetime.

The main types of blood vessels are: capillaries, arteries, and veins. Each type performs its specific functions. It is necessary to dwell on each of them in more detail.

Division into types and their characteristics

The classification of blood vessels is different. One of them involves division:

on arteries and arterioles;
precapillaries, capillaries, postcapillaries;
veins and venules;
arteriovenous anastomoses.

They represent a complex network, differing from each other in structure, size and their specific function, and form two closed systems connected to the heart - circulatory circles.

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The following can be distinguished in the device: the walls of both arteries and veins have a three-layer structure:

an inner layer that provides smoothness, built from the endothelium;
medium, which is a guarantee of strength, consisting of muscle fibers, elastin and collagen;
top layer of connective tissue.

Differences in the structure of their walls are only in the width of the middle layer and the predominance of either muscle fibers or elastic ones. And also in the fact that venous - contain valves.

arteries

They deliver blood saturated with useful substances and oxygen from the heart to all cells of the body. By structure, human arterial vessels are more durable than veins. Such a device (a denser and more durable middle layer) allows them to withstand the load of strong internal blood pressure.

The names of arteries, as well as veins, depend on:

Once upon a time it was believed that the arteries carry air and therefore the name is translated from Latin as “containing air”.

There are such types:

Arteries, leaving the heart, become thinner to small arterioles. This is the name of the thin branches of the arteries, passing into the precapillaries, which form the capillaries.

These are the thinnest vessels, with a diameter much thinner than a human hair. This is the longest part of the circulatory system, and their total number in the human body ranges from 100 to 160 billion.

The density of their accumulation is different everywhere, but the highest in the brain and myocardium. They consist only of endothelial cells. They carry out a very important activity: the chemical exchange between the bloodstream and tissues.

The capillaries are further connected to the post-capillaries, which become venules - small and thin venous vessels that flow into the veins.

These are the blood vessels that carry oxygen-depleted blood back to the heart.

The walls of the veins are thinner than the walls of the arteries, because there is no strong pressure. The layer of smooth muscles in the middle wall of the vessels of the legs is most developed, because moving up is not an easy job for the blood under the action of gravity.

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Venous vessels (all but the superior and inferior vena cava, pulmonary, collar, renal veins and veins of the head) contain special valves that ensure the movement of blood to the heart. The valves block the return flow. Without them, the blood would drain to the feet.

Arteriovenous anastomoses are branches of arteries and veins connected by fistulas.

Separation by functional load

There is another classification that blood vessels undergo. It is based on the difference in the functions they perform.

There are six groups:

There is another very interesting fact regarding this unique system of the human body. In the presence of excess weight in the body, more than 10 km (per 1 kg of fat) of additional blood vessels are created. All this creates a very large load on the heart muscle.

Heart disease and overweight, and even worse, obesity, are always very tightly linked. But the good thing is that the human body is also capable of the reverse process - the removal of unnecessary vessels while getting rid of excess fat (precisely from it, and not just from extra pounds).

What role do blood vessels play in human life? In general, they do a very serious and important job. They are a transport that ensures the delivery of essential substances and oxygen to every cell of the human body. They also remove carbon dioxide and waste from organs and tissues. Their importance cannot be overestimated.

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The structure and properties of the walls of blood vessels depend on the functions performed by the vessels in the integral human vascular system. As part of the walls of the vessels, the inner (intima), middle (media) and outer (adventitia) membranes are distinguished.

All blood vessels and cavities of the heart are lined from the inside with a layer of endothelial cells, which is part of the intima of the vessels. The endothelium in intact vessels forms a smooth inner surface, which helps to reduce resistance to blood flow, protects against damage and prevents thrombosis. Endothelial cells are involved in the transport of substances through the vascular walls and respond to mechanical and other influences by the synthesis and secretion of vasoactive and other signaling molecules.

The composition of the inner shell (intima) of the vessels also includes a network of elastic fibers, especially strongly developed in the vessels of the elastic type - the aorta and large arterial vessels.

In the middle layer, smooth muscle fibers (cells) are circularly located, capable of contracting in response to various influences. There are especially many such fibers in the vessels of the muscular type - the final small arteries and arterioles. With their contraction, there is an increase in the tension of the vascular wall, a decrease in the lumen of the vessels and blood flow in more distally located vessels up to its stop.

The outer layer of the vascular wall contains collagen fibers and fat cells. Collagen fibers increase the resistance of the walls of arterial vessels to the action of high blood pressure and protect them and venous vessels from excessive stretching and rupture.

Rice. The structure of the walls of blood vessels

Table. Structural and functional organization of the vessel wall

The inner, smooth surface of the vessels, consisting mainly of a single layer of squamous cells, the main membrane and the internal elastic lamina

Consists of several interpenetrating muscle layers between the inner and outer elastic plates

They are located in the inner, middle and outer shells and form a relatively dense network (especially in the intima), can easily be stretched several times and create elastic tension

They are located in the middle and outer shells, form a network that provides much more resistance to vessel stretching than elastic fibers, but, having a folded structure, counteract blood flow only if the vessel is stretched to a certain extent

They form the middle shell, are connected to each other and to elastic and collagen fibers, create an active tension of the vascular wall (vascular tone)

It is the outer shell of the vessel and consists of loose connective tissue (collagen fibers), fibroblasts. mast cells, nerve endings, and in large vessels additionally includes small blood and lymphatic capillaries, depending on the type of vessels, it has a different thickness, density and permeability

Functional classification and types of vessels

The activity of the heart and blood vessels ensures the continuous movement of blood in the body, its redistribution between organs, depending on their functional state. A difference in blood pressure is created in the vessels; the pressure in the large arteries is much higher than the pressure in the small arteries. The difference in pressure determines the movement of blood: blood flows from those vessels where the pressure is higher to those vessels where the pressure is low, from arteries to capillaries, veins, from veins to the heart.

Depending on the function performed, the vessels of large and small are divided into several groups:

shock-absorbing (vessels of elastic type);
resistive (vessels of resistance);
sphincter vessels;
exchange vessels;
capacitive vessels;
shunting vessels (arteriovenous anastomoses).

Cushioning vessels (main vessels, vessels of the compression chamber) - aorta, pulmonary artery and all large arteries extending from them, arterial vessels of the elastic type. These vessels receive blood expelled by the ventricles at relatively high pressure (about 120 mm Hg for the left and up to 30 mm Hg for the right ventricle). The elasticity of the great vessels will be created by a well-defined layer of elastic fibers in them, located between the layers of the endothelium and muscles. The shock-absorbing vessels stretch to receive the blood expelled under pressure by the ventricles. This softens the hydrodynamic impact of ejected blood against the walls of blood vessels, and their elastic fibers store potential energy that is spent on maintaining blood pressure and moving blood to the periphery during diastole of the ventricles of the heart. Cushioning vessels offer little resistance to blood flow.

Resistive vessels (vessels of resistance) - small arteries, arterioles and metarterioles. These vessels provide the greatest resistance to blood flow, as they have a small diameter and contain a thick layer of circularly arranged smooth muscle cells in the wall. Smooth muscle cells that contract under the action of neurotransmitters, hormones, and other vasoactive substances can dramatically reduce the lumen of blood vessels, increase resistance to blood flow, and reduce blood flow in organs or their individual areas. With relaxation of smooth myocytes, the lumen of the vessels and blood flow increase. Thus, resistive vessels perform the function of regulating organ blood flow and affect the value of arterial blood pressure.

Exchange vessels - capillaries, as well as pre- and post-capillary vessels, through which water, gases and organic substances are exchanged between blood and tissues. The capillary wall consists of a single layer of endothelial cells and a basement membrane. There are no muscle cells in the wall of capillaries that could actively change their diameter and resistance to blood flow. Therefore, the number of open capillaries, their lumen, the rate of capillary blood flow and transcapillary exchange change passively and depend on the state of pericytes - smooth muscle cells located circularly around the precapillary vessels, and the state of arterioles. With the expansion of arterioles and relaxation of pericytes, capillary blood flow increases, and with narrowing of arterioles and reduction of pericytes, it slows down. Slowing of the blood flow in the capillaries is also observed with the narrowing of the venules.

Capacitive vessels are represented by veins. Due to their high extensibility, veins can hold large volumes of blood and thus provide a kind of deposition - slowing down the return to the atria. The veins of the spleen, liver, skin and lungs have especially pronounced depositing properties. The transverse lumen of the veins in conditions of low blood pressure has an oval shape. Therefore, with an increase in blood flow, the veins, without even stretching, but only taking on a more rounded shape, can contain more blood (deposit it). In the walls of the veins there is a pronounced muscle layer, consisting of circularly arranged smooth muscle cells. With their contraction, the diameter of the veins decreases, the amount of deposited blood decreases and the return of blood to the heart increases. Thus, the veins are involved in the regulation of the volume of blood returning to the heart, influencing its contractions.

Shunt vessels are anastomoses between arterial and venous vessels. There is a muscular layer in the wall of the anastomosing vessels. When the smooth myocytes of this layer are relaxed, the anastomosing vessel opens and the resistance to blood flow decreases in it. Arterial blood is discharged along the pressure gradient through the anastomosing vessel into the vein, and the blood flow through the vessels of the microvasculature, including capillaries, decreases (up to cessation). This may be accompanied by a decrease in local blood flow through the organ or part of it and a violation of tissue metabolism. There are especially many shunting vessels in the skin, where arteriovenous anastomoses are switched on to reduce heat transfer, with the threat of a decrease in body temperature.

Vessels returning blood to the heart are medium, large and vena cava.

Table 1. Characteristics of the architectonics and hemodynamics of the vascular bed