10 - gums
11 - sublingual-maxillary fold
22 - language
30 - tooth enamel
31 - tooth crown

The tooth consists of dentin, enamel and cement.

Dentine- tissue that forms the basis of the tooth.
Dentin consists of a calcified matrix penetrated by dentinal tubules containing processes of odontoblast cells lining the tooth cavity. The intercellular substance contains organic (collagen fibers) and mineral components (hydroxyapatite crystals). Dentin has different zones, differing in microstructure and color.

Enamel- a substance covering dentin in the crown area. It consists of crystals of mineral salts, oriented in a special way to form enamel prisms. Enamel does not contain cellular elements and is not tissue. The normal color of enamel is from white to cream with a yellowish tint (distinguishable from plaque).

Cement- tissue covering dentin in the root area. The structure of cement is close to bone tissue. Consists of cementocyte and cementoblast cells and a calcified matrix. Nutrition of cement occurs diffusely from the periodontium.

Inside the tooth there is cavity, which is divided into coronal cavity And root canal, opening with the above about aperture of the tooth apex. Fills the dental cavity dental pulp, consisting of nerves and blood vessels immersed in loose connective tissue and providing metabolism in the tooth. Distinguish coronal And root pulp.

Gum- mucous membrane that covers the dental edges of the corresponding bones, fused tightly with their periosteum.
The gum covers the tooth in the neck area. It is abundantly supplied with blood (tendency to bleeding), but relatively poorly innervated. The grooved depression located between the tooth and the free edge of the gum is called the gingival sulcus.

The periodontium, alveolar wall and gums form supporting apparatus of the tooth - periodontium.

Periodontium- provides attachment of the tooth to the dental alveolus.
It consists of the periodontium, the wall of the dental alveoli and the gums. The periodontium performs the following functions: supporting and shock-absorbing, barrier, trophic and reflex.

CHANGE OF TEETH

A dog's teeth, like those of most mammals, are diphyodont type, that is, during the life of the animal there is one change of teeth: the first generation - temporary, or baby teeth replaced by second generation teeth - permanent. In dogs, only P1 teeth do not change; they erupt along with the baby teeth and remain permanent.

Table Timing of teething in dogs
(according to J. Hozgood et al., 2000).

Changing teeth (general X-ray)

TYPES OF TEETH

Dogs are heterodont animals, i.e. have teeth of different structures depending on the functions they perform. The following types of teeth are distinguished: incisors, fangs And molars: premolars (false, small molars), or premolars And truly indigenous, or molars that do not have milk precursors.

Teeth arranged in order in a row form topand lower dental arches (arcades) . The upper arcade is represented by 20, and the lower by 22 teeth (10 and 11 on each side, respectively).

Anatomy of the incisors of the upper arcade

Incisors

Between the margin and the canine of the upper arch, as well as the canine and the first premolar of the lower arch, there are spaces - diastemas, which ensure the closure of the canines.

The molars of each arcade increase in size distally to the largest secant teeth, also called predatory. Molars have a different structure on the upper and lower arches, and therefore their structure will be considered separately.

Premolars - 4 on each side.
P I - has 1 (rarely 2) crown tubercles and 1 root.
P 2.3 - the crown has 3 teeth: a large medial one and 2 smaller distal ones; the tooth has 2 roots - medial and distal;
P 4 - the crown has 3 tubercles: large medial
both distal and lesser lingual; There are 3 roots, they correspond to the tubercles in location.

Molars - 2 on each side. Their longitudinal axes are parallel to each other and perpendicular to the median plane.

M 1 - the crown has 6 tubercles: 2 large buccal, middle - lingual and 3 small between them. The tooth has 3 roots: powerful lingual
and 2 smaller buccal ones - medial and distal.
M 2 - the crown has 4-5 tubercles: 2 buccal (medial and distal) and 2-3 lingual. There are 3 roots, their location is similar to that of M 1.

P 1-4 are similar in structure to those of the upper arcade, with the exception of slightly longer and narrower roots.
The lower P 1 is sometimes referred to in the literature as a wolf tooth.

Molars- 3 on each side.

M 1 is the largest of the molars. The crown has 5 tubercles: medial, 2 distal and 2 middle between them: powerful buccal
and a smaller lingual. 2 roots: medial and distal.

M 2 - the crown has 3-4 tubercles: 2 medial and 2 distal. The tooth has 2 roots, identical in size: medial and distal.

M 3 is the smaller of the molars; the crown usually has 1 or 2 cusps. There is one root, rarely two.

DENTAL FORMULA

Recording teeth in the form of a number series, where each number indicates the number of teeth of a certain type on one side of each arcade in the direction from the median plane is called dental formula.

The dental formula is:
baby teeth D: ICP/ICP
molars: P: IСРМ/IСРМ.

Dog teeth formulas:
D: 3130/3130
R: 3142/3143.
Thus, 28 milk teeth (here we should not take into account the first premolars, which are essentially permanent teeth, although they erupt with the milk shift) and 42 permanent teeth.

In medical dental practice, the dental formula is written according to the following scheme: D: PCI|ICP/PCI|ICP; R: МРCI|ICРМ/ МРCI|ICРМ the number of teeth is reflected in the entire arcade, and not just on one side. In this case, the dog’s dental formula will look like D: 313| 313/ 313|313; R: 2413|3142/3413|3143.

This form of recording the dental formula seems to be the most rational. Using this type of notation, you can briefly designate any arcade tooth. For example, the permanent lower left second premolar is designated as P|P2, the deciduous upper right tooth as DI1|-, or OP for short]. The entry D|Р1 is erroneous,
since there is no primary first premolar in dogs.

BITE
The closure of the dental arcades is called occlusion, or occlusion.

When the dog's jaws close, the upper incisors come in front of the lower ones in such a way that the lingual surfaces of the former are in free contact with the vestibular (vestibular) surface of the latter, and the fangs freely enter the corresponding diastema, forming a so-called lock. This occurs because the upper dental arcade is slightly wider than the lower one (anisognathous arcades). Teeth touching are called antagonists.

The bite can vary depending on the shape and size of the jaws and incisal bone, the direction of growth of the incisors and canines, which in turn is determined by the breed, type of constitution of the animal, age and other factors.

The physiological occlusion options are:

Orthognathia or the scissor bite described above. Characteristic for dogs with gentle, strong and strong rough types of constitution. Is normal for most breeds. With this type of bite, wear of the incisors occurs most slowly.

If the lower incisors are located behind the upper ones, but are separated from them at some distance, such a bite is called undershot.
In this case, the mesial surface of the upper canines and the distal surface of the lower canines are worn down due to friction.
Such a bite may be caused by abnormalities in bone development (elongated upper jaw and/or shortened lower jaw - microgenia) or dental growth. It is more common in dogs of dolichocephalic breeds with a sharp muzzle. It is found in puppies with a massive head in the cheekbones and a wide lower jaw in the branches. As a rule, with the completion of the formation of the skeleton, the bite in such puppies is restored to a scissor or straight bite.
For adult dogs of most breeds it is considered a defect, as it significantly complicates eating and reduces the animal’s performance. In addition, with underbite, the fangs of the lower jaw do not form a lock, but injure the palate.

Progenia or snack- The lower incisors are located in front of the upper ones. Significant shortening of the bones of the facial region with a normal or elongated lower jaw causes the advancement of not only the lower incisors, but also the canines - a bulldog bite. It is standard for breeds such as English and French bulldogs, pugs, boxers and some others, provided that the incisors and canines of the lower jaw do not protrude beyond the upper lip.

Straight bite (pincer-shaped)- the incisors touch the edges.
This bite is typical for dogs of coarse and coarse loose constitution types with a massive lower jaw. For some breeds, a direct bite is allowed by the standard unconditionally or from a certain age. For example, the FCI-335 standard for the Central Asian Shepherd Dog breed (came into force on March 22, 2000) states: “scissor bite, straight or tight undershot (without waste), regardless of age.” With a straight bite, the incisors grind down most quickly.

The gradual erosion of enamel and dentin with age is a physiological process. At correct bite, physiological stress Adequate compensatory changes occur in the dental organ, ensuring the full functioning of worn teeth.

DATES FOR TEETH ABRASION

The timing of crown wear in dogs, as in other animals, depends on many factors. These include, first of all, bite. As stated above, with a scissor bite, grinding of the incisors and canines occurs much more slowly than with a straight (pincer) and other bite options.
We should not forget that in addition to the described types, there is a great variety of pathological forms of occlusion, in which the grinding of individual teeth occurs inappropriately for age.

Also, the intensity of crown abrasion is determined by feeding conditions, such as: consistency of food (dry or wet food); the depth of the dish from which the dog takes food, and the material from which it is made (does the dog have the ability to physiologically capture food and not injure its teeth). The habit of some dogs to chew and carry hard objects greatly affects the time it takes for the incisors and other teeth to wear down.

Of particular importance for tooth abrasion are individual characteristics microstructure and chemical composition enamel and dentin. Such deviations can be either congenital (hereditary factor, use of teratogenic drugs in pregnant dogs, severe feeding disorders and diseases during pregnancy) or acquired (disease and other diseases). infectious diseases during the period of changing teeth, taking tetracycline drugs in young animals, excess fluoride in the body (dental fluorosis), the use of aggressive chemicals (mineral acids) for treating the oral cavity, etc.

Taking into account the above factors, it becomes obvious that it is impossible to establish a strict relationship between the degree of abrasion of individual teeth and the age of the animal. The exception is animals under the age of 10-12 months, in which the order of eruption of permanent teeth is quite stable, and after its completion (6-7 months) up to 10-12 months, the crowns of permanent teeth finally move into the oral cavity.
Over 1 year, the correlation of erasure with age is very conditional.

Erasure of the trefoils of the lower incisors (2.5 years)

Below are the approximate timing of changes in the dental apparatus in dogs.

Shamrocks begin to wear off at around 2 years of age. First, they are ground down on the lower incisors, by 3 years - on the upper hooks, by 4 years - on the middle ones, and by 5-6 years, trefoils, as a rule, are absent on all incisors, except for the upper edges.

From 5-6 to 10-12 years, the lower incisors move forward with varying intensity (the lower hooks are usually the first to move forward), the canines and large tubercles of the molars wear down.

In dogs older than 10-12 years, the crowns of the lower toes are usually almost completely worn out. The crowns of other teeth are slightly evenly ground down. If the animal does not suffer from periodontal disease (which is rare in pet dogs), then natural tooth loss begins by the age of 14-17 years.

Note that with periodontitis and periodontal disease, total loss teeth by the age of 8-10 years.

A more reliable criterion for determining the age of a dog is the relative size of the tooth cavity. With age, there is a gradual decrease in the cavity of the tooth until it is completely obliterated in old dogs. This parameter is practically not influenced by external and internal factors and can be the basis for the development of a method for determining age.
To determine the size of the tooth cavity, it is necessary to take an x-ray. Using this technique, it will be possible to determine the age from an x-ray or a section, having only one tooth at your disposal.

MECHANICAL DIGESTION

Digestion in the oral cavity occurs mainly mechanically; when chewing, large fragments of food are broken into pieces and mixed with saliva. Chewing is especially important in terms of digestion of ingredients. plant origin, because nutrients are often enclosed in cellulose-containing membranes that cannot be digested. These membranes must be broken down before the nutrients inside can be used.

Mechanical digestion also allows you to increase the area exposed to action. digestive enzymes.

FOOT OF ORAL CAVITY

STRUCTURE

The floor of the oral cavity is covered with mucous membrane, located below the free surface of the tongue and on the sides of its body, it is a slit-like space under the sublingual mucosa. Sagittally, the floor of the mouth is divided by a fold of the frenulum of the tongue.

On the sides of the body of the tongue, the mucous membrane of the bottom with a thick submucosal layer forms folds into which multiple short ducts open sublingual salivary gland. Lateral to the frenulum of the tongue there are small sublingual (hunger) warts. They are the openings of the excretory ducts mandibular
and long duct sublingual salivary glands.

SALIVARY GLANDS

1 - parotid gland
2 - mandibular gland
3 - sublingual gland
7 - zygomatic gland

Maxillary (mandibular) salivary gland located behind the branch of the lower jaw, ventral to the parotid salivary gland, reaches the neck, where it lies between the maxillary veins.
It is large, oval in shape, yellowish-waxy in color and larger than the parotid gland. Its excretory ducts follow in the intermaxillary space over the premaxillary muscle medially from the sublingual salivary gland into the hungry warts. The gland secretes a serous mucous secretion.

Parotid salivary gland lies ventral to the auricle, relatively small in size. The excretory duct passes across the masticatory muscle and opens into the buccal vestibule with a low salivary papilla.

Sublingual salivary gland lies under the mucous membrane on the sides of the body of the tongue. Divided into multi-channel, which opens in a large number of ducts on the lateral surface of the sublingual fold, and single-duct- one duct - in a hungry wart. Produces a mucous secretion.

ENZYMATIVE DIGESTION

Saliva is secreted into the oral cavity by four pairs of salivary glands.
Typically, a small amount of saliva is present in the mouth, but the amount may be increased by the sight and smell of food. This effect, called the “taste reaction,” was first studied by academician I.P. Pavlov.

Salivation continues when food enters the oral cavity, and its effect is enhanced by chewing process.
Saliva is 99% water, while the remaining 1% is mucus, inorganic salts and enzymes.
Mucus acts as an effective lubricant and promotes swallowing, especially dry food. Unlike humans, the saliva of cats and dogs lacks the starch-digesting enzyme amylase, which prevents the rapid hydrolysis of starch in the oral cavity.
The absence of this enzyme is consistent with the observed behavior of dogs, which tend to swallow without chewing all but the hardest pieces of food, and the behavior of cats, characteristic of carnivores, which tend to consume foods with a low starch content.

LANGUAGE

Language- a muscular, movable organ lying at the bottom of the oral cavity.

Language structure

The papillae of the mucous membrane of the tongue perform the function of a taste analyzer; its surface provides thermoregulation of the dog’s body, and also performs the function of touch.

Curving like a spoon, the tongue serves to receive water.

By external form Dogs' tongues are long, wide and thin. The skeleton of the tongue is inner surface mandible, as well as the hyoid bone.

Language structure

2 - muscles of the tongue
3 - body of tongue
4 - root of tongue

In the language there are: root, body And top.

Root The tongue is located between the molars and is covered with the mucous membrane of the palatoglossal arch.
Body The tongue lies between the branches of the lower jaw; the back and lateral surfaces are distinguished on it. There are many papillae on the back. The dorsum of the tongue is concave and divided by a deep sagittal groove extending to the apex of the tongue. On the sides of the back, the lateral surfaces of the body of the tongue converge into its frenulum.

tip of tongue- its most mobile part, expanded and flattened, has a ventral surface free from the frenulum. The dorsal surface of the apex is noticeably wider than its dorsum.
In the thickness of the apex of the tongue lies a specific intralingual cartilage (a remnant of the intralingual bone), which supports the dog's protruding tongue and helps with the intake of liquid food.

PAPIPLES OF THE TONGUE

The papillae of the tongue are divided into mechanical And taste.

Mechanical:

1. Thread-like
Cover the entire dorsal surface of the tongue, long, thin
and soft.
2. Conical
Located in the area of ​​the root of the tongue instead of threadlike ones.

Flavoring(contain taste nerve receptors - taste buds):

1. Mushroom
Scattered over the entire surface of the back of the tongue among the threadlike ones.
2. Roll-shaped (grooved).
They lie on the border of the body and the root of the tongue in 2-3 pairs. They are large, round in shape, with a groove around each one. In the latter, the mucous glands open.
3. Leaf-shaped
They lie on the sides of the root of the tongue in front of the palatoglossus arches. Oval in shape, 0.5 - 1.5 cm long, divided into segments - “leaves”. Contains serous-mucous glands.

GLANDS OF THE TONGUE

The glands of the tongue are parietal, they are scattered over the entire surface and edges of the tongue, lie deep in the mucous membrane, and secrete a mucous secretion.

MUSCLES OF THE TONGUE

The tongue is based on striated muscle tissue. Her muscle fibers oriented in three mutually perpendicular directions: longitudinal (front to back), transverse (right to left) and oblique (top to bottom) and form differentiated muscles, which are divided into the muscles of the tongue and the hyoid bone.

The basis of the language is lingual muscle. It is built from vertical, oblique and longitudinal muscle fibers running from the hyoid bone to the tip of the tongue.
Function: changes the shape (thickness, length, width) of the tongue in different directions.

Lingual lateral muscle. It starts from the lateral surface of the middle segment of the hyoid bone and follows the lateral surface of the tongue to its apex.
Function: with bilateral action, pulls the tongue back, with one-sided - turns it in the corresponding direction.

Sublingual - lingual muscle. It begins on the body and laryngeal horns of the hyoid bone, ends in the thickness of the tongue medially from the lateral lingual muscle, lateral from the genioglossus.
Function: pulls the tongue back, flattens the root of the tongue when swallowing.

Genioglossus muscle. It begins on the mental angle of the lower jaw and branches fan-shaped in the midsagittal plane from the apex to the middle of the body of the tongue.
Function: flattens the tongue, moves it forward.

MUSCLES OF THE HYPOGLOUS

The geniohyoid muscle is fusiform and runs from the chin of the lower jaw to the hyoid bone.
Function: pulls the hyoid bone and with it the tongue forward. Provides maximum extension of the tongue when lapping or licking.

Transverse premaxillary (hyoid) muscle. It extends from the mental angle of the lower jaw, along the dental edge along the line of its muscular attachment to the tendon suture of the submandibular space and ends on the body and large horns of the hyoid bone.
Function: raises the tongue when chewing. Presses back to the hard palate.

Stylohyoid muscle - from the greater and lesser horns of the hyoid bone.
Function: brings the branches together when swallowing.

Hornohyoid muscle - follows from the laryngeal horns of the hyoid bone to its lesser horns.
Function: pulls up the named branches.

Hyoid retractor muscles - the sternohyoid and sternothyroid muscles retract the hyoid bone during swallowing.

2. Pharynx (Pharynx)

Throat - pharynx - a tube-shaped movable organ in which the digestive tract crosses, going through the pharynx from the oral cavity to the pharynx and further to the esophagus and the respiratory tract - through the choanae to the pharynx and further to the larynx.

1 - esophagus
2 - throat
4 - trachea
5 - larynx
6 – epiglottis

STRUCTURE

The pharyngeal cavity is divided into two different parts: the upper - respiratory - nasopharynx and the lower - digestive - (larynx), which are limited from each other by the velopharyngeal arch. The velopharyngeal arches converge before the beginning of the esophagus, forming the esophagopharyngeal border.

Respiratory part The pharynx, located under the base of the skull, serves as a continuation of the nasal cavity behind the choanae. It is lined with single-layer columnar ciliated epithelium, while the digestive part is lined with squamous stratified epithelium. The pharyngeal openings of the auditory (Eustachian) tubes open into the lateral parts of the nasopharynx, which connect the nasopharynx with the tympanic cavity of the middle ear (pharyngitis can provoke otitis media).

The anterior section of the digestive part of the pharynx borders the pharynx, from which it is separated by the velum palatine and, thus, serves as a continuation of the oral cavity, and is therefore called the oral cavity. At the back, it abuts the anterior surface of the epiglottis. Then, located on top of the larynx, the pharynx continues back to the entrance
into the esophagus. This part of the digestive section of the pharynx is called the laryngeal part, since the entrance to the larynx opens into it from below. Thus the pharynx has 7 holes.

On the dorsal wall of the pharynx in the area of ​​the fornix is ​​the pharyngeal tonsil.

The pharynx is located between the middle segments of the hyoid bone, they cover the organ from the sides, and the upper (proximal) segments of the hyoid bone suspend it from the mastoid part of the petrous bone.
Contraction of the pharyngeal muscles underlies the complex swallowing act, which also involves the soft palate, tongue, larynx, and esophagus.

Radiography: X-ray control
performing endoscopy of the pharynx area

At the same time, the pharyngeal levators pull it upward, and the compressors consistently narrow its cavity backwards, pushing the food bolus into the esophagus. At the same time, the larynx also rises, the entrance to it is tightly covered by the epiglottis, due to pressure on it with the root of the tongue. In this case, the muscles of the soft palate pull it upward and caudally in such a way that the velum palatine rests on the velopharyngeal arches, separating the nasopharynx.
During breathing, the shortened velum palatine hangs obliquely downward, covering the pharynx, while the epiglottis, built of elastic cartilage, directed upward and forward, provides access to a stream of air into the larynx.

The outside of the pharynx is covered with connective tissue adventitia.
It is attached to the base of the skull through the basilar pharyngeal fascia.

The basis of the pharynx is made up of three pairs of constrictors (narrowers) and one dilator (dilator). These paired muscles form a middle sagittal tendon suture on the upper wall of the organ, extending from the velopharyngeal arch to the esophagus.

1. Cranial (rostral) constrictor of the pharynx - consists of paired muscles: velopharyngeal and pterygopharyngeal.

The velopharyngeal muscle makes up the lateral walls of the cranial part of the pharynx, as well as the velopharyngeal arch, starts from the palatine and pterygoid bones and ends at the tendinous pharyngeal suture.
Function: brings the mouth of the esophagus closer to the root of the tongue.

The pterygopharyngeal muscle tendinously begins on the pterygoid bone and ends in the caudal part of the pharynx. Merges with the velopharyngeal muscle.
Function: pulls the pharyngeal wall forward.
The main function of the anterior pharyngeal constrictor is to block the entranceinto the nasopharynx and expansion of the esophagus.

2. The middle constrictor of the pharynx (hypoglossal muscle) is formed by: the cartilaginous and oropharyngeal muscles (belong to the group of muscles of the hyoid bone) - it follows from the laryngeal horns of the hyoid bone to the tendon suture of the pharynx.
Function: pushes the food bolus towards the esophagus.

3. The caudal constrictor of the pharynx is formed by: the thyropharyngeal muscle, going from the thyroid cartilage of the larynx to the tendinous suture, and the annular pharyngeal muscle, going from the annular cartilage to the pharyngeal suture.
Function: pushes the food bolus towards the esophagus.

Pharyngeal dilator - follows from the medial surface of the middle segment of the hyoid bone under the middle and caudal constrictors to the lateral surface of the pharynx.
Function: expands the posterior part of the pharynx after swallowing, narrows the nasopharynx.

3. Esophagus (Oesophagus)

Esophagus- is the initial part of the foregut
and in structure it is a typical tube-shaped organ. It is a direct continuation of the laryngeal part of the pharynx.

The mucous membrane of the esophagus along its entire length is collected
into longitudinal folds that straighten as the food bolus passes. The submucosal layer contains many mucous glands that improve the sliding of food. The muscular lining of the esophagus is a complex multi-level striated layer.

STRUCTURE

The outer membrane of the cervical and thoracic parts of the esophagus is connective tissue adventitia, and abdominal part covered with visceral peritoneum. The attachment points of the muscle layers are: laterally - the arytenoid cartilages of the larynx, ventrally - its annular cartilage, and dorsally - the tendon suture of the larynx.

Schematic representation of the esophagus

Along the way, the diameter of the esophagus is uneven: it has 2 expansions and 2 narrowings. In medium-sized dogs, the diameter at the inlet is up to 4 cm, and at the outlet up to 6 cm. There are cervical, thoracic and abdominal parts of the esophagus.

The total length of the esophagus is on average 60 cm, and the average diameter of the collapsed esophagus is about 2 cm. Topographically, the esophagus is divided into cervical, thoracic and abdominal parts. The cervical part is long and makes up about half the length of the esophagus. Directly behind the pharynx it is located above the tracheal semirings
and under the prevertebral layer of the fascia of the neck (surface plate).

Then, at the level of 4-6 cervical vertebrae, the esophagus makes a bend, descending to the left side of the trachea, and follows the entrance to the chest cavity. This feature of the topography allows you to avoid tension on the organ in the thoracic part during movements of the head and neck, at the same time, it should be taken into account during medical manipulations on the organ.

In the chest cavity in the mediastinum, the esophagus accompanies the trachea on the left, and then in the region of its bifurcation (bifurcation) again lies on the trachea. The thoracic part of the esophagus first passes over the base of the heart to the right of the aortic arch, then through the esophageal opening of the diaphragm, located at the level of the third intercostal space, slightly to the left. Behind the diaphragm, in the abdominal cavity, the short abdominal part of the esophagus forms the entrance to the stomach or cardiac opening (cardia).

FUNCTIONS

There is no secretion of digestive enzymes in the esophagus, however, the epithelial cells of the esophageal mucosa secrete mucus, which serves to lubricate the food coma during the process of peristalsis, automatic wave-like muscle contractions that are stimulated by the presence of food in the esophagus and ensure its movement through the digestive canal. The process of moving food from the mouth to the stomach takes only a few seconds.

4. Stomach (Ventriculus)

The dog's stomach is single-chamber, intestinal type. It is an extension of the digestive tube behind the diaphragm.

Appearance of an isolated stomach

1 - pyloric part of the stomach
2 - cardiac part of the stomach
3 - fundic part of the stomach
4 - exit of the duodenum
5 - cardial opening (entrance of the esophagus)

The external ventral flexure of the stomach is commonly called great curvature, and the dorsal small bend between the entrance and exit from the stomach is small curvature. The anterior surface of the stomach between the lesser and greater curvatures faces the diaphragm and is called diaphragmatic, and the opposite posterior surface is called visceral. It faces the intestinal loops.

On the side of the greater curvature, the greater omentum is attached to the stomach - gastric mesentery. It is very extensive, like an apron, it covers the entire intestine up to the hypogastrium and forms the omental sac. On the left surface of the greater curvature, in the fold of the omental sac, the spleen is adjacent to the stomach.
It is connected to the greater curvature of the stomach gastrosplenic ligament, in which numerous vessels are located. This ligament is a continuation of the mesentery of the stomach - the greater omentum.

The entrance to the omental sac is located between the caudal vena cava and the portal vein of the liver, medial to the right kidney. Small seal located on the lesser curvature, it is short and consists of gastrohepatic ligament. In the cranial direction it merges with esophagohepatic ligament, and in the caudal - with hepatoduodenal ligament. The above ligaments, in addition to the gastrosplenic ligament, perform only a mechanical function.

Endoscopy: the appearance of the stomach is normal

Endoscopy: appearance of the stomach.
Ulcerative gastritis

(various projections)

TOPOGRAPHY OF THE STOMACH

The stomach is located in the left hypochondrium in the region of the 9th - 12th intercostal space and the xiphoid cartilage (epigastrium); when filled, it can extend beyond the costal arch and descend onto the ventral abdominal wall.

In large dogs, this anatomical feature underlies the pathogenesis of non-contagious diseases of the stomach - its acute dilatation or volvulus.

PARTS OF THE STOMACH

It is customary to distinguish three parts of a single-chamber stomach: cardiac, fundus (fundic), pyloric, which differ not only in structure, but also in the specialization of the glands. The cardial part of the stomach is thicker and less blood-supplied compared to its other parts; this fact must be taken into account when performing surgical interventions.

The cardiac part is an extension behind the entrance
into the stomach and makes up 1/10 of the area of ​​its greater curvature. The mucous membrane of the cardiac part of the intestinal type is pinkish in color, rich in parietal cardiac glands, which secrete a serous-mucosal secretion of an alkaline reaction.

The middle part of the stomach behind the pars cardia on the side of the greater curvature is called the fundus of the stomach. It is the main part of the stomach where food is deposited in layers. There is located bottom gland zone(aka functional or bottom). In dogs, it occupies the left half of the greater curvature of the stomach.

The zone of the fundic glands is distinguished by a dark coloration of the mucosa, and is also equipped with gastric pits - the mouths of the parietal glands. The right half of the stomach is occupied zone of pyloric glands. The gastric mucosa, when unfilled, is gathered into folds. Only in the area of ​​lesser curvature are they oriented from the entrance to the stomach to the pylorus.

The pyloric part of the dog's stomach has a powerfully developed constrictor (narrower), which circumferentially covers it 5 - 7 cm from the entrance to the duodenum and ensures the evacuation of food from the stomach to the intestine.

MININGS OF THE STOMACH

Mucous membrane - white, lined with stratified squamous epithelium, collected in numerous longitudinal folds. The well-developed submucosal layer contains mucous glands.

The muscular lining of the stomach is made of smooth muscle tissue and has three layers of fibers: longitudinal, circular and oblique.

Longitudinal fiber layer thin follows from the esophagus to the pylorus. Circular layer located predominantly in the bottom
and pyloric parts of the stomach. It forms the pyloric constrictor.

Oblique layer predominates in the left half of the stomach; in the area of ​​the circular layer it doubles (into internal and external).

The serous membrane of the stomach passes from the lesser curvature into the lesser omentum, and from the greater curvature into the splenic ligament and greater omentum.

EMBRYOLOGY

During embryonic development, the stomach, as part of a straight digestive tube, undergoes two 180-degree rotations. One in the frontal plane counterclockwise and the other in the segmental plane.

FUNCTIONS

The stomach performs several functions:

It serves to temporarily store food and controls the rate at which food enters the small intestine

The stomach also secretes enzymes necessary for the digestion of macromolecules

The stomach muscles regulate motility, allowing food to move caudally (away from the mouth), and aid digestion by mixing and grinding food.

The dog's stomach is large in size; its maximum volume can approach the volume of the entire large and small intestines. This is due to the dog’s irregular feeding and eating food “for future use.”
It is known that a dog can also use its stomach as a temporary reservoir for storing food: for example, when feeding older puppies, the bitch regurgitates the food obtained for them.

PHASES OF STOMACH SECRETION

Gastric secretion is regulated by complex processes of nervous and hormonal interaction, thanks to which it is carried out at the right time and in the required volume. The secretion process is divided into three phases: cerebral, gastric and intestinal.

Brain phase

The medullary phase of secretion is initiated by the anticipation of food intake and the sight, smell and taste of food, which stimulates the secretion of pepsinogen, although gastrin and hydrochloric acid are also released in small quantities.

Gastric phase

The gastric phase is initiated by mechanical stretching of the gastric mucosa, a decrease in acidity, as well as products of protein digestion. In the gastric phase, the main secretion product is gastrin, which also stimulates secretion hydrochloric acid, pepsinogen and mucus. Gastrin secretion slows down sharply if the pH drops below 3.0 and may also be controlled by peptic hormones such as secretin.
or enteroglucagon.

Intestinal phase

The intestinal phase is initiated by both mechanical distension of the intestinal tract and chemical stimulation with amino acids and peptides.

5. Small intestine (Intestinum tenue)

STRUCTURE

The small intestine is a narrowed section of the intestinal tube.

The small intestine is very long, representing the main part of the intestine and ranges from 2.1 to 7.3 meters in dogs. Suspended on a long mesentery, the small intestine forms loops that fill most of the abdominal cavity.

The small intestine emerges from the end of the stomach and is divided into three different sections: the duodenum, the jejunum, and the ileum. The duodenum accounts for 10% of the total length small intestine, while the remaining 90% of the length of the small intestine consists of the jejunum and ileum.

BLOOD SUPPLY

The wall of the thin section is richly vascularized.

Arterial blood flows through the branches of the abdominal aorta - the cranial mesenteric artery, and to duodenum also along the hepatic artery.

Venous drainage occurs in the cranial mesenteric vein, which is one of the roots of the portal vein of the liver.

Lymphatic drainage from intestinal wall originates from the lymphatic sinuses of the villi and intraorgan vessels through the mesenteric (intestinal) lymph nodes into the intestinal trunk, which flows into the lumbar cistern, then into the thoracic lymphatic duct and cranial vena cava.

INNERVATION

The nervous supply of the small section is represented by branches of the vagus nerve and postganglionic fibers of the solar plexus from the semilunar ganglion, which form two plexuses in the intestinal wall: intermuscular (Auerbach's) between the layers of the muscular layer and submucosal (Meissner) in the submucosal layer.

Control of intestinal activity by the nervous system is carried out both through local reflexes and through vagal reflexes involving the submucosal nerve plexus and intermuscular nerve plexus. Intestinal function is regulated by the parasympathetic nervous system, the center of which is its medulla oblongata, from where the vagus nerve (10th pair of cranial nerves, respiratory-intestinal nerve) extends to the small intestine. Sympathetic vascular innervation regulates trophic processes in the small intestine.

TOPOGRAPHY

The thin section begins from the pylorus of the stomach at the level of the 12th rib, is covered ventrally by the leaves of the greater omentum, and is limited dorsolaterally by the thick section. There are no clear boundaries between the sections of the small intestine, and the identification of individual sections is mainly topographical in nature.

Only the duodenum is most clearly distinguished, which is distinguished by its large diameter and topographic proximity to the pancreas.

Contrast barium radiography of the small intestine

MININGS OF THE INTESTINAL

DEFINITION

The functional features of the small intestine leave an imprint on its anatomical structure. There are mucous membrane and submucosal layer, muscle (external longitudinal and internal transverse muscles) and serous membrane of the intestine.

INTESTINAL MUCOSA

The mucous membrane forms numerous devices that significantly increase the absorption surface.
These devices include circular folds, or Kirkring folds, in the formation of which not only the mucous membrane is involved, but also the submucosal layer and villi, which give the mucous membrane a velvety appearance. The folds cover 1/3 or 1/2 of the circumference of the intestine. The villi are covered with a special bordered epithelium, which carries out parietal digestion and absorption. The villi, contracting and relaxing, make rhythmic movements with a frequency of 6 times per minute, due to which they act as a kind of pumps during suction.

In the center of the villus there is a lymphatic sinus, which receives fat processing products. Each villus from the submucosal plexus contains 1-2 arterioles, which break up into capillaries. Arterioles anastomose with each other and during absorption all capillaries function, while during a pause there are short anastomoses. Villi are thread-like outgrowths of the mucous membrane, formed by loose connective tissue rich in smooth myocytes, reticulin fibers and immunocompetent cellular elements, and covered with epithelium.
The length of the villi is 0.95-1.0 mm, their length and density decreases in the caudal direction, that is, in the ileum the size and number of villi are much smaller than in the duodenum and jejunum.

HISTOLOGY

The mucous membrane of the thin section and villi is covered with a single-layer columnar epithelium, which contains three types of cells: columnar epithelial cells with a striated border, goblet exocrinocytes (secrete mucus) and gastrointestinal endocrinocytes.

The mucous membrane of the thin section is replete with numerous parietal glands - the common intestinal, or Lieberkühn's glands (Lieberkühn's crypts), which open into the lumen between the villi. The number of glands averages about 150 million (in the duodenum and jejunum there are 10 thousand glands per square centimeter of surface, and 8 thousand in the ileum).

The crypts are lined with five types of cells: epithelial cells with a striated border, goblet glandulocytes, gastrointestinal endocrinocytes, small borderless cells of the crypt bottom (stem cells of the intestinal epithelium) and enterocytes with acidophilic granules (Paneth cells). The latter secrete an enzyme involved in the breakdown of peptides and lysozyme.

LYMPHOID FORMATIONS

The duodenum is characterized by tubular-alveolar duodenal, or Bruner's, glands, which open into crypts. These glands are a continuation of the pyloric glands of the stomach and are located only on the first 1.5-2 cm of the duodenum.

The final segment of the thin section (ileum) is rich in lymphoid elements, which lie in the mucous membrane at different depths on the side opposite to the attachment of the mesentery, and are represented by both single (solitary) follicles and their clusters in the form of Peyer's patches.
Plaques begin in the final part of the duodenum.

The total number of plaques is from 11 to 25, they are round or oval in shape, length from 7 to 85 mm, and width from 4 to 15 mm.
The lymphoid apparatus takes part in the digestive processes.
As a result of the constant migration of lymphocytes into the intestinal lumen and their destruction, interleukins are released, which have a selective effect on the intestinal microflora, regulating its composition and distribution between the thin and thick sections. In young organisms, the lymphoid apparatus is well developed, and the plaques are large.
With age, a gradual reduction of lymphoid elements occurs, which is expressed in a decrease in the number and size of lymphatic structures.

MUSCULAR TRANSCRIPT

The muscular coat is composed of two layers of smooth muscle tissue: longitudinal And circular, and the circular layer is better developed than the longitudinal one.

The muscularis propria provides peristaltic movements, pendulum movements, and rhythmic segmentation that propel and mix the intestinal contents.

SEROSA

The serous membrane - the visceral peritoneum - forms the mesentery, on which the entire thin section is suspended. At the same time, the mesentery of the jejunum and ileum is better expressed, and therefore they are combined under the name mesenteric colon.

FUNCTIONS OF THE SMALL INTESTINE

In the small intestine, food digestion is completed under the action of enzymes produced by the wall (liver and pancreas) and parietal (Lieberkühn and Brunner) glands, absorption of digested products into the blood and lymph, and biological disinfection of incoming substances.
The latter occurs due to the presence of numerous lymphoid elements enclosed in the wall of the intestinal tube.

The endocrine function of the thin section is also great, which consists in the production of some biologically active substances by intestinal endocrinocytes (secretin, serotonin, motilin, gastrin, pancreozymin-cholecystokinin, etc.).

PARTS OF THE SMALL INTESTINE

It is customary to distinguish three sections of the thin section: the initial segment, or duodenum, the middle segment, or jejunum, and the final segment, or ileum.

DUODENUM

Structure
The duodenum is the initial section of the thin section, which is connected to the pancreas and the common bile duct and has the form of a loop facing caudally and located under the lumbar spine.

The length of the intestine is on average 30 cm or 7.5% of the length of the thin section. This section of the thin section is characterized by the presence of duodenal (Bruner's) glands and a short mesentery, as a result of which the intestine does not form loops, but forms four pronounced convolutions.

Barium contrast radiography
duodenum:

Topography
The cranial part of the intestine forms S-shaped, or sigmoid gyrus, which is located in the pylorus region, receives the ducts of the liver and pancreas and rises dorsally along the visceral surface of the liver.

Under the right kidney, the intestine makes a caudal turn - this cranial gyrus of the duodenum, and goes to descending part, which is located in the right iliac. This part passes to the right of the root of the mesentery and under the 5-6 lumbar vertebrae passes to the left side transverse part, dividing the mesentery into two roots in this place, and forms caudal gyrus of the duodenum.

The intestine is then directed cranial to the left of the mesenteric root as ascending part. Before reaching the liver, it forms duodelic jejunal gyrus and passes into the jejunum. Thus, a narrow loop is formed under the spine anterior root mesentery containing the right lobe of the pancreas.

JEJUNUM

Structure
The jejunum is the longest part of the small section and is about 3 meters, or 75% of the length of the small section.
The intestine got its name due to the fact that it has a half-dormant appearance, that is, it does not contain voluminous contents. It is larger in diameter than the ileum located behind it and is distinguished by a large number of vessels passing through a well-developed mesentery.
Due to its considerable length, developed folds, numerous villi and crypts, the jejunum has the largest absorption surface, which is 4-5 times greater than the surface of the intestinal canal itself.

Topography
The intestine forms 6-8 skeins, which are located in the region of the xiphoid cartilage, the umbilical region, the ventral part of both ilia and the groins.

ILEUM

Structure
The ileum is the final part of the thin section, reaching a length of about 70 cm, or 17.5% of the length of the thin section. Externally, the intestine is no different from the jejunum. This section is characterized by the presence of a large number of lymphoid elements in the wall. The final section of the intestine has thicker walls and the highest concentration of Peyer's patches. This section runs straight under the 1st-2nd lumbar vertebrae from left to right and in the area of ​​the right ilium flows into the cecum, connecting with it by a ligament. At the point where the ileum enters the cecum, the narrowed and thickened part of the ileum forms ileo-cecal valve, or ileal papilla, which has the appearance of a relief ring-shaped damper.

Topography
This section of the small intestine received its name due to its topographic proximity to the iliac bones, to which it is adjacent.

WALL GLANDS. LIVER.

Liver- the largest gland of the body, it is a parenchymal organ of dark red color, weighing 400-500 g, or 2.8-3.4% of body weight.

Five tubular systems are formed in the liver:
1) bile ducts;
2) arteries;
3) branches of the portal vein (portal system);
4) hepatic veins (caval system);
5) lymphatic vessels.

STRUCTURE OF A DOG'S LIVER

The shape of the liver is irregularly rounded with a thickened dorsal margin and sharp ventral and lateral margins. The pointed edges are dissected ventrally by deep grooves into lobes. The surface of the liver is smooth and shiny due to the peritoneum covering it, only the dorsal edge of the liver is not covered with peritoneum, which in this place passes onto the diaphragm, and thus forms extraperitoneal field liver.

Under the peritoneum there is a fibrous membrane. It penetrates the organ, divides it into lobes and forms perivascular fibrous capsule(Glisson's capsule), which surrounds the bile ducts, branches of the hepatic artery and portal vein.

The anterior surface of the liver - the diaphragmatic surface - enters the niche formed by the dome of the diaphragm, and the posterior surface - the visceral surface is in contact with organs located in the vicinity of the liver.

The dorsal margin has two notches: on the left - esophageal depression, and on the right - vena cava gutter. Located on the ventral edge cutting of the round ligament. In the center visceral surface located surrounded by connective tissue gate of the liver- this is the place where the vessels and nerves penetrate, where the common bile duct exits and where the hepatic lymph nodes lie.

The falciform ligament, which is a duplicate of the peritoneum passing from the diaphragm to the liver, is a continuation round ligament- remnant of the umbilical vein, divides the liver into two lobes: right- large and left- smaller. Thus, the entire portion of the liver located to the right of the round ligament is the right lobe.

On the right it lies on the liver gallbladder. The area of ​​the liver between the gallbladder and the round ligament is middle share. The middle lobe of the portal of the liver is divided into two sections: the lower one is called square fraction, and the top one is caudate lobe. The latter consists of caudate process, which has renal depression, And mastoid process , which occupies the lesser curvature of the stomach. Finally, the left and right lobes are divided
into two parts each: lateral and medial.

Thus, the liver has six lobes: right lateral, right medial, left lateral, left medial, quadrate and caudate.

The liver is a polymer organ in which several structural and functional elements can be distinguished: hepatic lobule, sector (a section of the liver supplied by a branch of the portal vein of the 2nd order), a segment (section of the liver supplied by a branch of the portal vein of the 3rd order), hepatic acinus (adjacent sections two adjacent lobules) and the portal hepatic lobule (areas of three adjacent lobules).

The classic morphofunctional unit is the hepatic lobule, which is hexagonal in shape, located around the central vein of the hepatic lobule.

The hepatic artery and portal vein, having entered the liver, are repeatedly divided into lobar, segmental, etc. branches all the way
to interlobular arteries and veins, which are located along the lateral surfaces of the lobules along with interlobular bile duct, forming hepatic triads. From these arteries and veins branches arise that give rise to sinusoidal capillaries, which flow into the central veins of the lobule.

The lobules consist of hepatocytes, which form trabeculae in the form of two cellular cords. One of the most important anatomical features of the liver is that, unlike other organs, the liver receives blood from two sources: arterial blood through the hepatic artery, and venous blood through the portal vein.

BILIARY TRACT AND BILE FORMATION

One of the most important functions of the liver is the process of bile formation, which led to the formation of the bile ducts. Between the hepatocytes that form the lobules, there are bile ducts that flow into the interlobular ducts, which, in turn, form two hepatic duct, coming out of each lobe: right and left. Merging, these ducts form the common hepatic duct.

The gallbladder is a reservoir for bile, in which bile thickens 3-5 times, since it is produced more than is required for the digestion process. The color of gallbladder bile in dogs is red-yellow.

The bladder lies on the quadrate lobe of the liver high from its ventral edge and is visible from both the visceral and diaphragmatic surfaces. The bubble has bottom, body And neck. The wall of the bladder is formed by the mucous membrane, a layer of smooth muscle tissue and is covered on the outside with peritoneum, and the part of the bladder adjacent to the liver is made up of loose connective tissue. The cystic duct originates from the bladder and contains spiral fold.

As a result of the fusion of the cystic duct and the common hepatic duct, the common bile duct is formed, which opens
into the S-shaped gyrus of the duodenum next to the pancreatic duct at the apex major duodenal papilla. At the point where it enters the intestine, the duct has bile duct sphincter(sphincter of Oddi).

Thanks to the presence of the sphincter, bile can flow directly into the intestines (if the sphincter is open) or into the gallbladder (if the sphincter is closed).

TOPOGRAPHY OF THE LIVER

The liver is located in front of the stomach and is in contact with diaphragm. Lies almost symmetrically in both hypochondriums. Caudal edge The liver corresponds to the costal arch; only in old animals the liver can protrude beyond the costal arch.
With X-ray and ultrasound examination the distance between the caudal edge of the liver and the diaphragm should be five times the length of the second lumbar vertebra.

The liver is held in position by ligamentous apparatus, which includes round ligament liver - connects the ventral edge of the liver with the umbilical ring, the ligament continues in falciform ligament, attaching the liver to the diaphragm; the liver is also connected to the diaphragm using the coronary ligament, the left triangular ligament; The liver is connected to the right kidney by the hepatorenal ligament, to the stomach by the hepatogastric ligament, and to the duodenum by the hepatoduodenal ligament.
3 - cavity of the gallbladder.

Longitudinal scanning of the gallbladder: 1 - gallbladder cavity,
2 - wall of the gallbladder,

Transverse scanning of the gallbladder, 1 - gallbladder cavity,
2 - wall of the gallbladder,

The liver receives blood supply through the hepatic arteries and portal vein, and venous outflow occurs through the hepatic veins into the caudal vena cava.

The innervation of the liver is provided by the vagus nerve through the extra- and intramural ganglia and the sympathetic hepatic plexus, represented by postganglionic fibers from the semilunar ganglion. The phrenic nerve takes part in the innervation of the peritoneum covering the liver, its ligaments and the gallbladder.

LIVER FUNCTIONS

The liver is a multifunctional organ that takes part in almost all types of metabolism, plays a barrier and disinfecting role, is a depot of glycogen and blood (up to 20% of blood is deposited in the liver), and performs a hematopoietic function in the embryonic period.

The digestive function of the liver is reduced to the process of bile formation, which promotes the emulsification of fats and the dissolution of fatty acids and their salts. Dogs secrete 250-300 ml of bile per day.

Bile is a mixture of bicarbonate ions, cholesterol, organic metabolites and bile salts. The basis on which bile salts work is fat. Bile salts break down large fat particles into small droplets, which interact with various lipases.

Bile also serves to excrete organic residues, such as cholesterol and bilirubin, during the breakdown of hemoglobin. Liver cells produce bilirubin from the blood and actively secrete it into bile. It is due to this pigment that bile acquires its yellow color.

Three-dimensional structure of a bile salt
indicating the polar and non-polar sides

WALL GLANDS. PANCREAS

The pancreas is a large, loose parenchymal organ, consisting of individual lobules united by loose connective tissue. By weight, iron is 30-40 g, or 0.20-0.25% of body weight, and the color is pale pink.

According to the structure of the iron, it belongs to the complex tubular-alveolar glands of mixed secretion. The gland does not have clear contours, since it does not have a capsule, is stretched along the initial section of the duodenum and the lesser curvature of the stomach, covered with peritoneum ventro-caudally, the dorsal part is not covered with peritoneum.

The pancreas consists of exocrine lobules and endocrine parts.

Anatomically, the gland is divided into body, which is located in the S-shaped gyrus of the duodenum, left the lobe or gastric lobe, which is adjacent to the lesser curvature of the stomach, lies in the duplicate of the omentum and reaches the spleen and left kidney, and right lobe, or duodenal blade, which lies in the duplicate of the mesentery of the duodenum and reaches the right kidney.

In dogs, the right lobe is highly developed, so the gland has an elongated (ribbon-like) shape bent at an angle. The gland has a main (virzung) pancreatic duct, which leaves the body of the gland and opens next to the bile duct at the top of the duodenal papilla (sometimes the duct may be absent),
and 1-2 accessory (Santorini) ducts, which open at a distance of 3-5 cm from the main one.

The blood supply to the gland is provided by the branches of the splenic, hepatic, left gastric and cranial mesenteric arteries, and venous outflow occurs into the portal vein of the liver.

Innervation is carried out by branches of the vagus nerve and the sympathetic plexus of the pancreas (postganglionic fibers from the semilunar ganglion).

FUNCTIONS OF THE PANCREAS

The pancreas is responsible for both exocrine and endocrine functions, but in the context of this section, only exocrine digestive functions are considered.
The exocrine pancreas is responsible for secreting digestive secretions and large volumes of sodium bicarbonate ions, which neutralize the acidity of the chyme that comes from the stomach.

Secretion products:

Trypsin: breaks down whole and partially digested proteins into peptides various sizes, but does not cause the release of individual amino acids.
- chymotrypsin: breaks down whole and partially digested proteins into peptides of various sizes, but does not cause the release of individual amino acids.
- carboxypeptidases: cleaves individual amino acids from the amino terminus of large peptides.
- aminopeptidases: cleaves individual amino acids from the carboxyl end of large peptides.
- Pancreatic lipase: hydrolyzes neutral fat into monoglycerides and fatty acids.
- pancreatic amylase: hydrolyzes carbohydrates, converting them into smaller di- and trisaccharides.

6. Large intestine (Intestinum crassum)

The large intestine is the final section of the intestinal tube, averages 45 cm in length and is divided into the cecum, colon and rectum. It has a number of characteristic features, which include relative shortening, volume, low mobility (short mesentery), and the presence of a blind outgrowth - the cecum - on the border with the thin section.

1 - stomach
2, 3, 4, 5 - duodenum
6 - jejunum
7 - ileum
8 - cecum
9, 10, 11 - colon
12 - rectum

The blood supply to the colon is provided by the branches of the cranial and caudal mesenteric arteries, and the rectum is supplied by three rectal arteries: cranial(branch of the caudal mesenteric artery), middle and caudal(branches of the internal iliac artery).

Venous drainage from the cecum, colon and cranial portion of the rectum occurs into the portal vein of the liver. From the middle and caudal portions of the rectus cat into the caudal vena cava, bypassing the liver.

Innervation of the thick section is provided by branches vagus(transverse position of the colon) and pelvic nerves(blind, most of the colon and rectum). The caudal part of the rectum is also innervated by the somatic nervous system through the pudendal and caudal rectal nerves of the sacral spinal plexus. Sympathetic innervation is carried out through the mesenteric and rectal plexuses, which are formed by postganglionic fibers of the semilunar and caudal mesenteric ganglia.

Muscle control from the nervous system is carried out both through local reflexes and through vagal reflexes involving the submucosal nerve plexus and the intermuscular nerve plexus, which is located between the circular and longitudinal muscle layers. Normal bowel function is regulated by the parasympathetic nervous system. Control is directed from the medullary part of the vagus nerve to the anterior part and from the nuclei sacral region spine
through the pelvic nerve to the peripheral part of the large intestine.

The sympathetic nervous system (control directed from the ganglia in the paravertebral sympathetic trunk) plays a less important role. The processes of local control and coordination of motility and secretion of the intestine and associated glands are of a complex nature, involving nerves, paracrine and endocrine chemicals. The nervous supply of the small section is represented by branches of the vagus nerve and postganglionic fibers of the solar plexus from the semilunar ganglion, which form two plexuses in the intestinal wall: intermuscular (Auerbach's) between the layers of the muscular layer and submucosal (Meissner) in the submucosal layer.

Control of intestinal activity by the nervous system is carried out both through local reflexes and through vagal reflexes involving the submucosal nerve plexus and intermuscular nerve plexus.
Bowel function is regulated by the parasympathetic nervous system. Control is directed from the medullary portion of the vagus nerve to the small intestine. The sympathetic nervous system (control directed from the ganglia in the paravertebral sympathetic trunk) plays a less important role.
The processes of local control and coordination of motility and secretion of the intestine and associated glands are of a more complex nature; nerves, paracrine and endocrine chemicals take part in them.

The loops of the large intestine are located in the abdominal and pelvic cavities.

MEMBRANES OF THE LARGE INTESTINE

The structure of the colon consists of several layers: mucous membrane, submucosal layer, muscular layer (2 layers - outer longitudinal layer and inner circular layer) and serosa.

The epithelium of the cecum does not contain villi, but has numerous goblet cells on the surface that secrete mucus.

The mucous membrane does not have villi or circular folds, which is why it is smooth. Villi are present only in the embryonic state and disappear soon after birth. This is sometimes observed in some dogs in the first days of life, and in most individuals by the end of the second week.

The following types of cells are distinguished in the mucous membrane: intestinal epithelial cells with a striated border, goblet enterocytes, borderless enterocytes - the source of restoration of the mucous membrane, and single intestinal endocrinocytes. Paneth cells, present in the small intestine, are absent in the large intestine.

The intestinal (Lieberkühn) glands are well developed, lie deep and close to each other, and there are up to 1000 glands per 1 cm2.

The openings of the liberkühn glands give the mucous membrane an uneven appearance. In the initial part of the thick section, there is an accumulation of lymphoid elements that form plaques and lymphatic fields. An extensive field is located in the cecum at the confluence of the ileum, and plaques are located on the body of the cecum and at its blind end.

The muscular layer in the thick section is well developed, which gives the entire thick section a thick appearance.

FUNCTIONS OF THE THICK SECTION

Undigested food debris enters the large intestine and is exposed to the microflora inhabiting the large intestine. The digestive capacity of the large intestine of dogs is negligible.

Some excreta (urea, uric acid) and heavy metal salts are released through the mucous membrane of the large intestine; water is intensively absorbed mainly in the initial part of the colon. The thick section is functionally more of an organ of absorption and excretion than of digestion, which leaves an imprint on its structure.

PARTS OF THE LARGE INTESTINE

The large intestine consists of three main parts: cecum, colon And rectum.

CAECUM

Structure
The cecum is a blind outgrowth at the border of the thin and thick sections. The ileocecal entry foramen is well marked and represents an obturator mechanism.
The exit cecum-colic opening is not clearly defined and does not have a locking mechanism. The cecum in dogs is greatly reduced. It has the appearance of a convoluted appendage, making from 1 to 3 curls, its walls are enriched with lymphoid elements, but the intestine does not have a vermiform appendix, characteristic of higher primates. Depending on the size and number of curls, 5 types of dog cecum can be distinguished.

Topography
The intestine hangs on the mesentery on the right in the lumbar region under the 2-4 lumbar vertebrae, its length ranges from 2 to 16 cm, or 11% of the length of the thick section.

The cecum forms a pouch, closed at one end, located below the junction of the large and small intestines. In cats, the cecum is a vestigial organ, while in dogs the size of the cecum is significant.

COLON

Structure
The colon makes up the main volume of the thick section.
It reaches about 30 cm in length, or 66.7% of the total length of the thick section. The intestine is very narrow (narrower than the duodenum), but thick-walled. The shape forms a rim located in the frontal plane, under the spine, which in appearance resembles a horseshoe.
The colon consists of three relatively straight sections: the ascending colon, the transverse colon
and the descending colon, which continues into the rectum.

Topography
The colon begins on the right in the lumbar region and runs in the dorsal part of the right ilium in a straight line to the diaphragm as the ascending colon.
Behind the diaphragm (in the hypochondrium) it forms a transverse bend - the transverse colon and, moving to the left side, goes caudally in the dorsal part of the left iliac as the descending colon. Having reached the left groin, the sigmoid colon forms a sigmoid bend and passes into the rectum.

RECTUM

Structure
The rectum is the final segment of the large intestine. The length of the rectum is about 10 cm, or 22.2% of the length of the colon. The intestine is suspended on the mesentery, and in the pelvic cavity it is surrounded by loose connective tissue (pararectal tissue).

In the pelvic cavity, the intestine forms a poorly developed ampulla.
The rectum has smooth, elastic and thick walls, with a uniformly developed muscle layer. The mucous membrane is collected in longitudinal folds and contains modified Lieberkühn glands and numerous mucous glands that secrete large amounts of mucus.
There are many venous plexuses in the submucosal layer, due to which water and aqueous solutions from the rectum are well and quickly absorbed.

Topography
Lies under the sacrum and the first caudal vertebrae, ending with the anus.

Anus
The perineal part of the rectum is called the anal canal. The mucous membrane of the rectum 2-3 cm before the anus ends with the anorectal line, caudal from which the stratified squamous epithelium begins. In this area, two ring-shaped zones are formed. Inner zone called the columnar zone of the anus, the longitudinal folds of which are called the anal columns. Between them, depressions are formed - anal sinuses, in which mucus secreted by the anal glands accumulates.

The outer zone is called the intermediate zone, which is separated from the skin zone of the anus by the anal cutaneous line.
In the latter, the circumferential glands and paranal sinuses open. The rectum and anus have their own muscular apparatus, which in the anal area is represented by two sphincters: external and internal. The first is an accumulation of smooth muscle tissue around the anus, formed from the muscular layer of the rectum, and the second is striated muscle. Both sphincters function synchronously.

A number of muscles extend from the anus to the sides:

The rectal-tail muscle is represented by a longitudinal layer of the rectal musculature, which passes from the walls of the rectum to the first caudal vertebrae;
- levator anus - originates from the ischial spine and goes from the side of the rectum to the muscles of the anus;
- suspensory ligament of the anus - originates from the 2nd caudal vertebra and in the form of a loop covers the rectum from below; built of smooth muscle tissue; in males it becomes a retractor of the penis; and in females it ends in the labia.

The liver is a red-brown organ. This is the largest gland in the body. Its functions are very diverse: 1) the liver secretes bile, which enters the duodenum through the excretory ducts and promotes the digestion of fats; 2) participates in metabolism; 3) is a site for the deposition of carbohydrates (glycogen); 4) plays a barrier (protective) role - various toxic substances entering it from the stomach and intestines through the portal vein are destroyed in the liver; protein breakdown products present in the blood are neutralized, processed by liver cells into urea; 5) during the embryonic period, the liver also performs a hematopoietic function.

There are two surfaces on the liver: convex - anterior, or diaphragmatic, and concave-posterior, or visceral, adjacent to the stomach, intestines, pancreas and right kidney. On the visceral surface there is a transverse groove called the porta hepatis. It is the entry point of the hepatic artery, portal vein and nerves and the exit point of the hepatic duct and lymphatic vessels.

The edges of the liver are distinguished: the lower one is sharp, encircling the liver from below and from the sides, and the upper one is blunt. On the upper edge there are two notches - for the posterior vena cava and for the esophagus. On the sharp edge of the liver in all domestic animals, two more or less deep notches are visible, right and left, which divide the liver into three main lobes: right, left and middle (Fig. 1). The gate of the liver divides the middle lobe into the lower - quadrate and upper - caudate. The latter forms the caudate process. In pigs and dogs, the right and left lobes of the liver are each divided into two lobes. In horses, the liver has three main lobes, but the left lobe is subdivided into two more lobes.

Rice. 1. Layout of the liver lobes:

A - large horned lambing; B - small ruminants; IN -

4 - right lateral lobe; 4′ - right medial lobe; 5 - gallbladder; 6 - portal vein.

Liver covered serosa, under which there is a connective tissue capsule that separates layers of interlobular connective tissue into the organ. They divide the liver tissue into small ovoid or prismatic sections called lobules (Fig. 2). In omnivores, the connective tissue layers are very thick and the lobules are clearly visible to the naked eye. The connective tissue layers contain blood and lymphatic vessels, nerves, and bile ducts.

Rice. 2. Scheme of the structure of the hepatic lobule:

1 - interlobular connective tissue; 2- interlobular bile duct in it; 3 - it is in a longitudinal section; 4- interlobular vein; 5 - central vein of the lobule; 6 - intralobular capillaries flowing into it; 7-beams of the liver.

Each lobule consists of liver cells arranged in radial cords that secrete bile. These cords are called hepatic beams. In a cross section, each hepatic beam appears to consist of two cells, between which an intralobular fertilized capillary passes. The capillaries merge into interlobular excretory bile ducts, forming the hepatic duct.

The central vein is located in the axial part of the lobule. The liver receives blood from two sources: the portal vein and the hepatic artery. The portal vein collects blood from the intestines, stomach, spleen and pancreas. Having entered the thickness of the liver, the portal vein branches into interlobular veins, and they, in turn, into intralobular venous capillaries. In the center of the lobule, the capillaries merge into the central vein. The central veins of the lobules collect into the hepatic veins. Through the hepatic veins, blood from the liver is drained into the posterior vena cava. The hepatic artery, carrying blood from the aorta, branches parallel to the portal vein and with its capillaries flows into the intralobular venous capillaries.

The gallbladder is a reservoir for storing bile. Its outer shell is serous, followed by muscular, and then the inner, mucous membrane. The excretory duct of the gallbladder is called cystic duct. Merging with the hepatic duct, it forms the bile duct, which opens into the duodenum. Horses do not have a gallbladder, and the hepatic duct opens into the duodenum.

In its position, the liver is held by ligaments: it is connected to the diaphragm by 3-4 ligaments, and to the stomach and duodenum by the lesser omentum.

In ruminants, the entire liver lies in the right hypochondrium, in the horse, partially in the left hypochondrium, in pigs and dogs, almost evenly in the right and left hypochondrium.

Features of the anatomy and physiology of dogs and cats.

Skeletal system

The skeleton plays an important role in the life of the body. It serves as a lever of movement, support for the soft parts of the body, protection, a place for the development of hematopoietic organs, and also participates in metabolic and biochemical processes in the body. The skeleton of carnivores is unique in its structure. Distinctive features of the skeletal system are strength and lightness compared to other tissues. Young animals have more elastic bones than older animals. As we age, bones become more brittle.

Muscular system

Plays an important role in the exterior and models the body in relief. Mobility and flexibility of the body, active muscle activity (dog muscles have few tendons) are the distinctive features of the animal. The muscles of the limbs, back and lower back are of particular importance for the movement of the dog. No less important are the muscles of the chest and abdomen, which ensure breathing, and the muscles of the head, primarily the chewing muscles, which allow powerful clenching of the jaws.

Leather and wool

The skin that covers the body of carnivores consists of three layers: the epidermis, the skin itself and the subcutaneous tissue. In the skin itself there are hair follicles, sweat, aromatic and fat glands with capillary vessels and nerve endings. The subcutaneous layer contains adipose tissue. Tufts of hair grow at the cuticle, each of which contains 3 or more thick and long hairs (guard hairs), which form the outer coat, and 6-12 short, delicate hairs (undercoat).

The fur covers almost the entire body (with the exception of the nose, toe pads and slight hair on the scrotum in males). Above the eyes, on the cheekbones, temples and upper lip there are long and very stiff hairs (tactile tentacles). In the spring it is subject to molting, and in the fall it grows warmer fur.

Sweat glands are located in the skin of the paws, this is where sweat is secreted. That is why carnivores do not sweat throughout the body, and temperature deviations are evened out by accelerated breathing through an open mouth and evaporation of liquid from the oral cavity.

The skin also contains scent glands that produce a characteristic odor.

Digestive system

The digestive apparatus provides the nutritional process, which consists of capturing food and its mechanical crushing, absorption and creation of nutrients necessary for the body. The digestive system of dogs and cats is focused on animal, meat foods. IN gastrointestinal tract, which is approximately five times the length of the body and is relatively short compared to carnivores and omnivores, in which fiber digestion occurs in the anterior chambers of multilocular ruminants and in the large intestine and cecum. According to the evolutionary type of nutrition of carnivores, they do not have enzymes that digest carbohydrates in the salivary glands; the digestion of carbohydrates occurs due to pancreatic enzymes (in limited quantities), and minor microbial synthesis in the intestines.

Oral cavity.

The functional and morphological division of teeth allows an animal in natural conditions to grab prey, hold it, kill it, tear out pieces and, after rough grinding, prepare food for ingestion through reproduction; in this case, the premolars are used for biting, the molars are used for splitting. The change of teeth and the eruption of molars occurs quite early, so that dogs at a relatively young age already have a fully functioning dental system. There are individual and breed-related temporary deviations from the timing of teeth changes. Grinding of teeth also depends on the breed, type of keeping and feeding, and purpose of the dog. The absence of premolars (P1 and P2) and molars (M2 of the upper jaw and M3 of the lower jaw) is observed quite often in certain breeds (for example, shepherd dogs, dachshunds).

The formula for permanent teeth is 3I3C1P1M═30. The cat's dental system erupts at 3I2C1P1M

The most powerful teeth a cat has are its dagger-shaped fangs.

The tongue of carnivores is used mainly for receiving liquid food.

In this regard, the top of the dog's tongue has the shape of a scapula; in a cat, liquid absorption is carried out by dipping and quickly retracting the tip of the tongue, which is covered with a large number of densely located papillae.

Esophagus.

The esophagus begins behind the pharynx. In dogs and cats, at the level of the caudal border of the pharyngeal constrictors, there is an elevation on the mucous membrane - the pharyngoesophageal border. In a dog, this ridge protruding into the lumen of the pharynx contains glands, but in a cat it does not. The esophagus can be palpated in the distal third of the neck on the left side of the trachea. In a dog, the esophagus is entirely built of striated muscle tissue, while in a cat, striated muscle fibers are present only in the cranial third of the organ. In a cat, in the caudal part of the esophagus on the side of the mucous membrane there are constant transverse folds, which, when passing through a barium suspension, form a typical pattern (“herringbone”) on an X-ray image.

Stomach.

The stomach of dogs and cats is simple, single-chamber. Its size and shape, as well as its position, can vary greatly depending on the degree of fullness, which can vary quite significantly. The basic form describes the shape of the stomach in a state of moderate filling: it is a U-shaped curved sac, with its cranial adjacent surface adjacent to the diaphragm and liver, and with its caudal visceral surface facing the intestine. The wall of the stomach consists of mucous, muscular and serous membranes. Carnivores are characterized by the presence in the stomach of a well-developed base of the mucous membrane (submucosal layer), which is separated from the lamina propria of the mucous membrane by a two-layer muscular lamina mucosa. Between the muscular plate and the glands, first of all, a cat regularly wedges a layer of compact substance: this should be understood as a layer of fibrous connective tissue, which provides protection from sharp parts (bone fragments, etc.) in food gruel. The mucous membrane of carnivores over the entire area of ​​the stomach contains three types of glands: cardiac, bottom and pyloric.

Through the gastric mucosa, a small amount of mineral salts, grape sugar, and water is absorbed into the blood.

The small intestine is a section of the digestive apparatus where, under the action of enzymes, hydrolytic breakdown of food mainly occurs. The resulting breakdown products are absorbed mainly in the small intestine. The sections of the small intestine - duodenum, jejunum and ileum - do not have any significant differences in dogs and cats. Only in dogs, depending on the breed, the length of the small intestine can vary from 1 to 5 m, and in cats it always averages 1.30 m.

The large intestine primarily absorbs water and electrolytes. It takes three times longer for parts of food to be eliminated to pass through the large intestine than to pass through the small intestine. Despite this, the large intestine in dogs and cats is quite short. It is divided into the cecum, colon and rectum.

Pancreas.

The pancreas is both an exocrine and an endocrine gland. The body of the pancreas consists of two lobes. The pancreas of the dog and cat is shaped like a boomerang and has dorsal and ventral surfaces. Pancreatic juice contains proteolytic and nucleolytic enzymes (trypsin, chemotrypsin, carboxypeptidases, elastase, nucleases, aminopeptidase, collagenase, dipeptidase), amylolytic enzymes (a-amylase, maltase, lactase, invertase) and lipolytic enzymes (lipase, phospholipase, cholinesterase, carboxylesterase , monoglyceride lipase, alkaline phosphatase). The intrasecretory part of the gland is represented by the islets of Langerhans, which make up about 30% of the mass of the gland. There are several types of islets of Langerhans based on their ability to secrete polypeptide hormones: A-cells produce glucagon, B-cells produce insulin, D-cells produce samostatin. The bulk of the islets of Langerhans (about 60%) are B cells.

Liver.

The liver performs various functions in the body. The liver is involved in various metabolic processes, is an accumulating organ, takes harmful substances from the blood and neutralizes them, secretes bile. Therefore, it is connected by a system of ducts to the duodenum. The peculiarities of the functioning of the liver are associated with the originality of its cells, hepatocytes, and with its unique inclusion in the circulatory system.

Respiratory system

The respiratory organs carry out gas exchange between the blood and atmospheric air. They regulate air flow depending on the load on the body and the need for oxygen. Through the nasopharyngeal canal, through the nasopharynx and trachea, air enters the lungs. Gas exchange occurs in the alveoli of the lung, which are covered by a dense network of capillaries. Here, oxygen coming from the external environment enters the bloodstream, and carbon dioxide from the blood into the alveoli. On the way to the lungs, the air is purified, moistened and warmed. The air flow is directed through the nostrils and larynx. The change in breathing from nasal to oral also plays a certain role.

The lungs of dogs and cats are distinguished by very deep interlobar fissures. These slits extend through the dorsal margin almost to the base of the lung. Sometimes the left interlobar fissure is not so deep.

The left lung is divided into two approximately equal lobes, cranial and caudal. The cranial lobe is further divided into cranial and caudal parts. Due to the limited space between the heart and the lateral chest wall, this part of the lung can only expand to a small extent. The caudal part slightly covers the cranial part behind. In the region of the obtuse (dorsal) edge there is no separation between the parts. The caudal part is compact, pyramidal in shape with its base on the diaphragm.

The right lung in dogs and cats is divided into cranial, caudal and accessory lobes. The cranial lobe is almost completely separated from the remaining lobes by the cranial interlobar fissure. The cranial contour of this lobe is more rounded in a dog, while in a cat it is pointed. The middle lobe is located between the cranial and caudal lobes. A pointed end protrudes from it ventrally. The cranially directed sharp edge of the middle lobe forms, together with the caudally directed sharp edge of the anterior lobe, the cardiac notch. The accessory lobe in dogs and cats differs most noticeably from the other lobes in shape. Its middle part is relatively thick and has three processes directed dorsally, ventrally and laterally. The accessory lobe is fused with the medial surface of the caudal lobe. It juts into the mediastinal recess and literally “sits astride” the posterior vena cava. Thus, its caudal surface is adjacent to the pericardium, the medial surface is adjacent to the caudal mediastinum, the caudal surface is adjacent to the diaphragm, and part of the lateral surface is on the medial side to the mesentery of the posterior vena cava.

Urinary system.

Bud

The kidney in dogs and cats is smooth, single-papillary, and bean-shaped. In a dog, the kidneys, depending on how full of blood they are, are colored from red-brown to bluish-red; in a cat, they are yellowish-red, light and dark. The size and weight of a dog's kidneys vary significantly depending on the breed, and in addition, in the same dog, both kidneys can differ in weight and size. In a cat, both kidneys have approximately the same mass. With increasing age, the mass of the kidneys also increases. The kidneys are located on either side of the median plane under the dorsal abdominal wall. The dog's right kidney is always located slightly more cranially than the left. Both kidneys are palpable through the abdominal wall. In a cat, both kidneys may be at approximately the same level; in any case, the right kidney does not extend into the subcostal part of the abdominal cavity. It is fixed by the hepatorenal ligament to the caudate process of the liver, however, unlike the dog, it does not form a depression on the liver. The left kidney has a longer mesentery, so its position is less constant. Both kidneys of the cat are also palpable.

In dogs and cats, the kidneys are enclosed in a fatty capsule. Depending on body fat, kidney fat is expressed more or less. With severe depletion of the fat capsule, the kidney, especially the left one, descends into the abdominal cavity, pulling with it the peritoneum covering it in the form of a mesentery.

The urinary organs include the renal pelvis, ureters, bladder and urethra. All urinary organs lined with transitional epithelium, which forms a reliable barrier to urine under high pressure.

The renal pelvis is a reservoir for urine and is a thin-walled sac that matches the shape of the renal papilla. The renal pelvis covers the renal papilla in a funnel-shaped manner. Along the edge of the pelvis there are 10-12 in a dog or 8-10 in a cat double pockets - recesses of the renal pelvis, which protrude along the edges of the pelvis, penetrating into the parenchyma of the kidney. Between both layers of each recess, a pair of interlobular vessels, a vein and an artery, pass to the border between the cortex and the medulla.

The ureter is a musculocutaneous tube and consists of adventitial, muscular and mucous membranes. The inside of the ureter, like the renal pelvis, is lined with transitional epithelium.

The bladder is very elastic, especially in dogs. There is a body of the bladder and a cranial apex, and a caudal neck. Regardless of the filling of the bladder, its body always lies in the abdominal cavity in front of the pubic crest. Therefore, it is always palpable and easily accessible for surgical interventions. The top of the bladder, especially in dogs that are taken out once a day, may extend to the umbilicus and beyond. The transitional epithelium of the bladder changes depending on the degree of filling of the bladder into more or less multilayered. Along with the barrier function, it also carries out, to a small extent, the exchange of ions, mucin and fats.

The urethra reveals strong gender differences in its structure.

The female's urethra is relatively short and wide. It stretches from the internal opening of the urethra to the external opening of the urethra, located on the border of the vagina and the vestibule of the vagina (urogenital vestibule). In this case, the female's urethra passes between the pelvic floor and the vagina. The structure of the wall of the urethra is basically similar to the structure of the wall of the bladder neck. In dogs, when extremely full and dilated, the bladder can also be used as a reservoir for urine and expand.

The male's urethra is significantly longer than that of the female; in male dogs and cats it differs due to various shapes and position of the penis. The pelvic part of the urethra is divided into the pre-representative part and the prostatic part. The preprostatic part stretches from the internal opening of the urethra to the spermatic colliculus, to which the prostatic ducts extend from the side. On the arch of the urethra in this part, its crest is visible, ending with the seminal mound. At this point, the vas deferens flow into the urethra and it becomes the urogenital canal. The prostate, or pelvic, part is mostly covered by the muscle of the urethra. At the exit from the pelvis, the pelvic part of the urethra passes into the penile, or spongy, part. In cats, the junction is marked by the bulbourethral gland. The spongy tissue surrounding the pelvic part of the urethra in the form of stratum spongiosum continues on the spongy part as the corpus spongiosum of the penis. The male's urethra ends at the external opening on the head of the penis.

Urination in males occurs, as is known, when the hind paw is raised on a tree (post, corner of the house). In this case, a small amount of urine is always released (urinary mark). For cats, urine marking also has great value. At the same time, raising their tail vertically, they release a thin stream of urine up and down onto bushes or walls of houses. In the case of exclusively indoor keeping of cats, it is necessary to provide for the presence of so-called cat litter boxes with walls.

Cardiovascular system

The cardiovascular system includes: blood, blood vessels through which blood moves, and the heart - the organ that ensures the movement of blood through the vessels.

The heart has the shape of a cone, the wide part of which is directed upward and forward with its base, and the narrowed part (apex). The heart is located in the chest cavity, between the lungs, in a special bag - the cardiac sac.

Inside, the heart is divided into four sections by two partitions. The longitudinal partition is blind. It divides the heart into two separate halves: right and left. The transverse septum has openings and divides the heart into upper and lower halves (atria and ventricles).

The walls of the heart consist of three layers. The middle layer formed by the heart muscle is best developed. The heart hangs in the chest cavity on vessels extending from it and attached to the spinal column. It is held from below by a cardiac sac attached to the sternum.

Blood vessels depart from each part of the heart: from the right atrium, the vena cava, through which blood is collected in the heart from the entire body; from the left atrium the pulmonary veins, through which blood comes from the lungs; from the right ventricle the pulmonary artery, through which blood is directed to the lungs; from the left ventricle is the aorta artery, through which blood is sent to all organs.

In order for blood to move continuously in one direction, the heart has valves located between the atria and ventricles, as well as between the ventricles and arteries.

Blood enters the heart through the veins and fills the atria. When both atria fill with blood, their muscles simultaneously contract and push blood into the ventricles. After this, the muscles relax and a new portion of blood enters the atria. At this time, the muscles of both ventricles begin to contract simultaneously, blood is driven into the arteries, after which the muscles relax. When the ventricles contract, blood cannot flow back into the atria, since the opening between them is closed by valves. In the same way, blood from the arteries cannot pass back into the ventricles: the openings in them are closed by valves. Thanks to this structure of the heart, blood continuously moves in one direction: from the veins to the atria, then to the ventricles, and from them to the arteries. The closing of the valves is accompanied by sounds that can be heard. These sounds are called heart sounds. The work of the heart is judged by the nature of the heart sounds.

After each contraction, the heart muscles are at rest for some time; During the day, the heart works for about 10 hours, and rests the rest of the time. The heart of a dog in a calm state beats about 70 times per minute. The nature of the heart’s work is influenced by external temperature, physical activity, the presence of certain diseases, the effects of medications, and stimulation of the nervous system.

The work of the heart is constantly controlled by the brain. The brain regulates the frequency and force of heart contractions.

Blood vessels are divided into arteries, capillaries and veins. This division is determined by the structure of the vessels and the direction of blood movement in them.

Arteries are vessels that carry blood away from the heart. The largest arteries - the pulmonary and aorta - begin from the ventricles of the heart (from the right - pulmonary, from the left - aorta). The further from the heart, the thinner the arteries become, and so on until they turn into capillaries - the thinnest vessels visible only under a microscope. The artery wall is thick and contains elastic fibers, thanks to which these vessels easily stretch and compress again, like a rubber tube. The walls of small arteries contain muscles that can expand or reduce the lumen of the vessel. At the moment when the next portion of blood enters the arteries from the ventricle of the heart, they stretch. Once the blood flow stops and the heart valves close, the stretched arteries begin to contract and push blood further away from the heart. As a result, the adjacent section of the artery, which has thinner walls, expands. Thus, after each contraction of the ventricles of the heart, expanded and compressed sections will constantly move through the arteries. The contraction of the arteries resembles the movement of a wave. These movements are called a pulse wave, or pulse; they can be felt on any artery. The nature of the pulse is also used to judge the work of the heart.

Capillaries are the thinnest and shortest (no more than 2 mm) vessels that form the transition from arteries to veins. Their number is enormous: capillaries penetrate all organs and approach almost every cell. The number of working capillaries is not constant and depends on the needs of a particular organ. For example, during physical work, blood through the muscle passes nine times more capillaries than during rest.

The walls of capillaries consist of a single layer of cells. Between them there are holes through which the liquid part of the yrovi passes - plasma and white flares.

Veins are vessels through which blood moves to the heart. The vena cavae approach the right atrium, and the pulmonary veins approach the left atrium. The closer to the heart, the less number veins, but their walls become thicker, and they themselves become wider. Veins have valves inside them that allow blood to flow only to the heart.

Blood moves through the body through a closed system formed by the heart and blood vessels. In this case, the blood makes two circles: a large circle of blood circulation - the left ventricle, through the entire circle of the body to the right atrium (at this time it washes all the cells and tissues of the body, ensuring their metabolism); pulmonary circulation - from the right ventricle, only through the lungs to the left atrium (on this path, the blood releases carbon dioxide into the lungs and is enriched with oxygen). In dogs, blood passes through these two circles in approximately 17 seconds. If the body is at rest, then not all the blood moves through the vessels, but only the required amount. The rest of the blood remains motionless in a kind of “depot”. Such “depots” for blood are muscles, liver, spleen and skin. With increasing physical activity, the necessary part of the blood moves from the “depot” to common system blood circulation

All cells of the body are washed by tissue fluid, which contains all the necessary chemicals. The cells release all harmful “waste” into this same fluid. Tissue fluid is continuously renewed due to the liquid part of the blood - plasma coming from the capillaries. Excess of this fluid enters the lymphatic vessels, and through them into large vein, going to the right atrium, i.e. it enters the general blood flow again.

The composition of blood includes: the liquid part - plasma and cells, which are divided into three groups. The composition of plasma changes continuously and depends on the location of blood collection. The first group includes red round cells without a nucleus; they are continuously destroyed and replaced by new ones formed in bone marrow. Round cells contain hemoglobin, with which oxygen and carbon dioxide enter the blood. White cells included in the second group are varied in shape and size. They all have cores, and some have the ability to move. Just like red cells, white cells are continuously destroyed and replaced by newly formed ones. They fight microbes that enter the body, destroy worn-out cells and tissues, and are therefore called the “orderlies” of the body. Blood platelets are formed in the bone marrow and have a variety of shapes. These plates ensure the process of blood clotting.

(Nerag), a large lobular gland of an animal organism, involved in the processes of digestion, metabolism, blood circulation, maintaining the constancy of internal. body environment. It is located in the anterior part of the abdominal cavity directly behind the diaphragm, lying mostly in the right hypochondrium.

Anatomy. P. has a convex, diaphragmatic surface and a concave surface in contact with the stomach and intestines. On the right blunt end there are notches for the esophagus and posterior vena cava, on the visceral surface there is a transverse depression, which includes the hepatic [hepatic] artery and portal vein; this is where the excretory bile ducts come out [bilious] ducts and lymphatic vessels located lymphatic. nodes and nerve plexus. On the same surface in the right sagittal fossa there is a bile duct. [bilious] bladder, in the left there is a round ligament. P. is divided by grooves into the right, left and middle lobes (the latter is divided into the lower quadrate and upper caudal). In his [his] position P. is held by ligaments (Fig. 1). The core of P. is a connective tissue capsule. In the area of ​​the gate, the capsule, together with ducts, vessels and nerves, penetrates into the P. and creates [creates] internal network, differently developed in different animal species.

P.'s weight in cows is 3.2-3.4 kg, in sheep up to 800 g, in pigs up to 1.5 kg, in horses 1.5-3.5 kg. Histology. P. consists of hepatic [hepatic] lobules - small polygonal sections of parenchyma. P.'s lobulation and the structure of the lobules are determined by the structure of the organ's vascular system. P. includes hepatic [hepatic] artery and portal vein. Both vessels branch into lobar, segmental, interlobular parts. From the interlobular arteries and veins, entwining and delimiting one lobule from another, the perilobular arteries and veins extend. The latter break down into hepatic [hepatic] sinusoids, which penetrate the lobule and rush towards it in the radial direction [her] the center where the central vein is formed. The latter, having left the lobule, flows into the sublobular vein. These veins form the hepatic veins [hepatic] veins The terminal branches around the lobular artery at the periphery of the lobules flow into the hepatic [hepatic] sinusoids. Thus, venous and arterial blood mix in the sinusoids (Fig. 2).

Between the sinusoids there are radial cords (beams) of the liver [hepatic] hepatocyte cells. They are multifaceted in shape, with 1-2 (sometimes more) rounded nuclei and developed organelles and inclusions (Fig. 3). Surface of hepatocytes facing [converted] to the sinusoid, has microvilli. The wall of the sinusoid is built from a special endothelium; its cells (stellate, Kupffer's) are capable of phagocytosis. The endothelium of the sinusoid does not have a basement membrane and is surrounded by [surrounded] sinusoidal space filled with blood plasma, which promotes the most complete exchange of substances between blood and hepatocytes. On the surface of two neighboring hepatocytes, grooves are formed - bile grooves [bilious] tubules without a wall. Her [Her] The role is played by the plasmalemma of hepatocytes. Surface of the bile [bilious] the tubule is uneven, equipped with microvilli. Bile [Bile] flows from the lobules through the bile ducts [bilious] tubules, which on the periphery of the lobules are covered with a single-layer cube. epithelium and form interlobular bile [bilious] duct. The latter is located near the interlobular veins and arteries as part of the hepatic [hepatic] triad.

Physiology. Specific P.'s function is bile formation. Bile [Bile] formed in the liver [hepatic] cells and accumulates in the bile [gallery] bladder, and in animals that do not have a gallbladder [bilious] bladder (horse, camel, deer), - in the gallbladder [bilious] passages from where it enters the duodenum. Substances transported by blood are subjected to chemical reactions in P. transformations. In P., restructuring and formation of new amino acids are carried out by [by] deamination, transamination and direct amination reactions; intensive biosynthesis of hepatic [hepatic] proteins and essential proteins blood plasma. Glycogen is synthesized in P. from glucose, fructose, and galactose. P. has the ability to synthesize fat from fatty acids and glycerol, as well as break down fat into glycerin and fatty acids. P. influences water-salt metabolism and acid-base balance. In P., excess water is removed from the blood, which goes [goes] for the formation of lymph and bile [bile]. P. also participates in the metabolism of minerals and hormones, deposits blood, produces fibrinogen, as well as substances that promote (prothrombin) and prevent (antithrombine, heparin) coagulation [collapse] blood. During the period of embryonic development in P., hematopoiesis. Protective function P. consists of neutralizing toxic substances (phenols, ammonia, etc.) entering the organ from the gastrointestinal tract. tract, by [by] combining them with sulfuric and glucuronic acids and glycine. Ammonia in P. turns into urea, certain toxic metals (mercury, lead, etc.) bind to nucleoproteins and partially transform into harmless compounds. P.'s Kupffer cells can retain and phagocytose certain microbes, and hepatocytes are capable of destroying microbial toxins.

P.'s research is carried out by [by] palpation, percussion, biopsy, functional tests, laparoscopy.

Palpation of P. is possible mainly. in dogs, cats and sheep (the animals are placed on the right side, the fingers of the right hand are passed from the right side under the last rib and the right edge of the p. is felt). In this case, it is possible to establish an increase, soreness, and a change in the consistency of the pus. In large animals, the enlarged pus can be palpated rectally. Percussion gives [gives] positive diagnostic the result is only with a significant increase in P. U cr. horn. livestock hepatic region [hepatic] dullness normally occupies the right side top part 10th, 11th and 12th intercostal spaces: the posterior border runs along a line extending from the lateral edge of the transverse costal space [transverse costal] process of the 1st lumbar vertebra down and forward [forward] to the point where the border of the lungs crosses [lungs] with the 10th rib. As P. increases, the boundaries in the 12th intercostal space reach the level of the line of the ischial tuberosity or to the level of 1/2 of the scapula, in the 11th intercostal space - to the level of 2/3 of the scapula. In a horse, with a significant increase in P., percussion along the macular line on the right, in the area of ​​the 15th and 16th intercostal spaces, reveals a dull sound and pain. In dogs, the area of ​​dullness is on the right from the 10th to the 13th rib, on the left - in the area of ​​the 11th intercostal space. Violations of P.'s activity are detected using a set of tests reflecting various functions of P. Biochemical tests are carried out. blood, urine, feces tests (determination of bilirubin, urobilin, proteins, fibrinogen, prothrombin, sugar, lactic and pyruvic acid, cholesterol, hippuric acid, transminases, aldolase, alkaline phosphatase, etc.). See also Van den Bergh method.

Pathology P.-see. in articles Hepatitis, Toxic liver dystrophy, Jaundice, Cirrhosis, Gallstone [Cholelithiasis] disease.

Lit.: Clinical diagnosis of internal diseases of agriculture. animals, ed. V. I. Zaitseva, 3rd ed., M., 1971; Akaevsky A.I., Anatomy of Domestic Animals, 3rd ed., M., 1975; Ivanov I.F., Kovalsky P.A., Cytology, histology, embryology, 3rd ed., M., 1976; Physiology of agriculture Animals, L., 1978 (Manual of Physiology).

309 rub

Emergency and intensive care for small animals

Book " Ambulance and intensive care of small domestic animals" is a reference manual dedicated to providing assistance in the most common critical conditions. The book consists of two sections. First, the basic principles of initial stabilization and life support are described. important functions of the entire animal body, and then a systematic approach to the most common critical conditions. Each section begins with a clinical approach to a patient presenting with signs of critical illness in each body system, and then describes treatment regimens for specific diseases. This guide also contains information on monitoring and management of critically ill patients.
The material in the book is presented in the form of small abstracts so that you can quickly find the necessary information. All information is numbered and contains numerous links to provide as much information as possible. full description various emergency conditions. The book also contains many useful formulas, tables, illustrations and drug doses.

This reference book is a must-have for any veterinary emergency specialist, both newly graduated and professional, since there should always be a source at hand that contains all the necessary information.

2630 rub

Horse diseases. Modern methods of treatment

For recent years The number of equine specialists has increased enormously, and the technology for diagnosing and treating animals has reached a completely new level, which allowed the authors to create this voluminous work of a thousand pages.
The uniqueness of the book lies in the fact that the authors of the chapters are practicing veterinarians - the best specialists in each of the areas presented here, working in the largest foreign veterinary centers and clinics for horses.
This publication contains more than 1000 pages, which are divided into 17 sections covering a wide range of equine diseases.
In this edition:

sufficient attention has been paid to the rapidly developing field of clinical pharmacology;

includes an extensive section on infectious diseases;

sufficiently in-depth research on gastrointestinal, skin, cardiovascular, ophthalmological diseases and diseases of foals;

The topic of reproduction of offspring is discussed in detail.
The authors have given the chapters of the book an easy-to-read structure, including a description of the characteristic clinical symptoms of diseases and functional disorders, various treatment regimens, with an emphasis on the practical side of diagnosis and treatment.
In the original, this book went through five editions over twenty years, and now for the first time it has been published in Russian.

The work "Equine Diseases. Modern Methods of Treatment" is an indispensable desktop guide for practitioners all over the world. veterinarians- equine specialists and students of veterinary medicine.

Introduction

In recent years, throughout the world there has been a steady increase in diseases of the liver and biliary tract, of various etiologies, resulting in severe complications.

According to the prevalence of liver diseases in Russia, we can distinguish:

in first place is toxic hepatitis - more than 50%,

in second place is viral hepatitis, 24% of patients.

the third most common cause is autoimmune hepatitis 10-13%,

Liver diseases affect 28% of people - and this is almost a third of all those studied. Cholecystitis and cholelithiasis are much more common than hepatitis.

The topic under study is relevant due to the progressive growth of diseases of the liver and gall bladder, against the background of the latent course of the disease, the low frequency of patients seeking help from a doctor and not always correct diagnosis diseases.

The purpose of the course work is to prove the need to use modern methods for diagnosing liver and gallbladder diseases in the work of clinicians.

The object of the study is diseases of the liver and gall bladder.

The subject of the research is modern methods for diagnosing liver and gall bladder diseases.

To achieve this goal it is necessary:

1) Reveal the anatomical and physiological features of the structure of the liver and gall bladder, the functions of these organs and their diseases.

2) Consider the main complaints and syndromes in pathology of the liver and gall bladder.

3) Determine the main methods for diagnosing diseases of the liver and gall bladder.

Chapter 1. Liver diseases

Anatomy, structure, functions of the liver

Liver (Latin jecur, jecor, hepar, other Greek ἧπαρ) is a vital exocrine gland of vertebrate animals, including humans, located in the abdominal cavity (abdominal cavity) under the diaphragm and performs a large number of different functions. physiological functions.

The liver is the largest gland in vertebrates.

The liver, hepar, is a voluminous glandular organ (weight about 1500 g).

The functions of the liver are diverse. It is primarily a large digestive gland that produces bile, which enters the duodenum through the excretory duct. (This connection of the gland with the intestine is explained by its development from the epithelium of the foregut, from which part of the duodenum develops.)

It is characterized by a barrier function: toxic products of protein metabolism, delivered to the liver with the blood, are neutralized in the liver; in addition, the endothelium of the hepatic capillaries and stellate reticuloendotheliocytes have phagocytic properties (lymphoreticulohistiocytic system), which is important for the neutralization of substances absorbed in the intestine.

The liver is involved in all types of metabolism; in particular, carbohydrates absorbed by the intestinal mucosa are converted in the liver into glycogen (“glycogen depot”).

The liver is also credited with hormonal functions.

In the embryonic period, it is characterized by the function of hematopoiesis, as it produces red blood cells.

Thus, the liver is simultaneously an organ of digestion, blood circulation and metabolism of all types, including hormonal.

The liver is located directly under the diaphragm, in the upper part of the abdominal cavity on the right, so that only a relatively small part of the organ extends to the left of the midline in an adult; in a newborn it occupies most of the abdominal cavity, equal to 1/20 of the total body weight, while in an adult the same ratio drops to approximately 1/50.

The liver has two surfaces and two edges. The upper, or more precisely, the anterosuperior, surface, facies diaphragmatica, is convex according to the concavity of the diaphragm to which it is adjacent; the lower surface, facies visceralis, faces down and back and bears a number of impressions from the abdominal viscera to which it is adjacent. The upper and lower surfaces are separated from each other by a sharp lower edge, margo inferior. The other edge of the liver, the superoposterior, on the contrary, is so blunt that it can be considered as the posterior surface of the liver.

There are two lobes in the liver: the right, lobus hepatis dexter, and the smaller left, lobus hepatis sinister, which are separated from each other on the diaphragmatic surface by the falciform ligament of the liver, lig. falciforme hepatis. The free edge of this ligament contains a dense fibrous cord - the circular ligament of the liver, lig. teres hepatis, which stretches from the navel, umbilicus, and is an overgrown umbilical vein, v. umbilicalis. The round ligament bends over the lower edge of the liver, forming a notch, incisura ligamenti teretis, and lies on the visceral surface of the liver in the left longitudinal groove, which on this surface is the boundary between the right and left lobes of the liver. The round ligament occupies the anterior section of this groove - fissiira ligamenti teretis; the posterior section of the groove contains a continuation of the round ligament in the form of a thin fibrous cord- overgrown ductus venosus, ductus venosus, functioning in the embryonic period of life; this section of the groove is called fissura ligamenti venosi.

The right lobe of the liver on the visceral surface is divided into secondary lobes by two grooves, or depressions. One of them runs parallel to the left longitudinal groove and in the anterior section, where the gallbladder is located, vesica fellea, is called fossa vesicae felleae; the posterior section of the groove, deeper, contains the inferior vena cava, v. cava inferior, and is called sulcus venae cavae. Fossa vesicae felleae and sulcus venae cavae are separated from each other by a relatively narrow isthmus of liver tissue called the caudate process, processus caudatus.

The deep transverse groove connecting the posterior ends of the fissurae ligamenti teretis and fossae vesicae felleae is called the portal of the liver, porta hepatis. Through them enter a. hepatica and v. portae with the accompanying nerves and the lymphatic vessels and ductus hepaticus communis, which carries bile from the liver, emerge.

Part right lobe The liver, bounded at the back by the portal of the liver, at the sides by the fossa of the gallbladder on the right and the fissure of the round ligament on the left, is called the quadratic lobe, lobus quadratus. The area posterior to the gate of the liver between the fissura ligamenti venosi on the left and the sulcus venae cavae on the right constitutes the caudate lobe, lobus caudatus. Organs in contact with the surfaces of the liver form depressions on it, impressiones, which are called the organ in contact.

The liver is covered for most of its length by peritoneum, with the exception of part of its posterior surface, where the liver is directly adjacent to the diaphragm.

The structure of the liver.

Beneath the serous membrane of the liver is a thin fibrous membrane, tunica fibrosa. In the area of ​​the liver gate, together with the vessels, it enters the substance of the liver and continues into the thin layers of connective tissue surrounding the liver lobules, lobuli hepatis.

In humans, the lobules are weakly separated from each other; in some animals, such as pigs, the connective tissue layers between the lobules are more pronounced. Liver cells in the lobule are grouped in the form of plates, which are located radially from the axial part of the lobule to the periphery. Inside the lobules in the wall of the hepatic capillaries, in addition to endothelial cells, there are stellate cells with phagocytic properties. The lobules are surrounded by interlobular veins, venae interlobulares, which are branches of the portal vein, and interlobular arterial branches, arteriae interlobulares (from a. hepatica propria).

Between the liver cells, which make up the liver lobules, located between the contacting surfaces of two liver cells, there are bile ducts, ductuli biliferi. Coming out of the lobules, they flow into the interlobular ducts, ductuli interlobulares. Exits from each lobe of the liver excretory duct. From the confluence of the right and left ducts, the ductus hepaticus communis is formed, which carries bile from the liver, bilis, and emerges from the portal of the liver.

The common hepatic duct most often consists of two ducts, but sometimes of three, four or even five.

Topography of the liver. The liver is projected onto the anterior abdominal wall in the epigastric region. The borders of the liver, upper and lower, projected onto the anterolateral surface of the body, converge with one another at two points: on the right and on the left.

The upper border of the liver begins in the tenth intercostal space on the right, along the midaxillary line. From here it rises steeply upward and medially, corresponding to the projection of the diaphragm, to which the liver is adjacent, and along the right nipple line reaches the fourth intercostal space; from here the border gently descends to the left, crossing the sternum slightly above the base of the xiphoid process, and in the fifth intercostal space it reaches the middle of the distance between the left sternum and left nipple lines.

The lower border, starting in the same place in the tenth intercostal space as the upper border, goes from here obliquely and medially, crosses the IX and X costal cartilages on the right, goes along the epigastric region obliquely to the left and up, crosses the costal arch at the level of the VII left costal cartilage and in the fifth intercostal space it connects with the upper border.

Ligaments of the liver. The liver ligaments are formed by the peritoneum, which passes from the lower surface of the diaphragm to the liver, to its diaphragmatic surface, where it forms the coronary ligament of the liver, lig. coronarium hepatis. The edges of this ligament have the form of triangular plates, designated as triangular ligaments, ligg. triangulare dextrum et sinistrum. Ligaments extend from the visceral surface of the liver to the nearest organs: to the right kidney - lig. hepatorenale, to the lesser curvature of the stomach - lig. hepatogastricum and to the duodenum - lig. hepatoduodenal.

The liver is nourished by a. hepatica propria, but in a quarter of cases from the left gastric artery. The peculiarities of the liver vessels are that, in addition to arterial blood, it also receives venous blood. Through the gate, a. enters the substance of the liver. hepatica propria and v. portae. Entering the gate of the liver, v. portae, carrying blood from the unpaired organs of the abdominal cavity, branches into the thinnest branches located between the lobules - vv. interlobulares. The latter are accompanied by aa. interlobulares (branches of a. hepatica propia) and ductuli interlobulares.

In the substance of the liver lobules themselves, arteries and veins form capillary networks, from which all the blood collects in the central veins - vv. centrales. Vv. centrales, leaving the liver lobules, flow into the collecting veins, which, gradually connecting with each other, form vv. hepaticae. The hepatic veins have sphincters where the central veins enter them. Vv. hepaticae in the amount of 3-4 large and several small ones emerge from the liver on its posterior surface and flow into the v. cava inferior.

Thus, there are two venous systems in the liver:

portal, formed by branches v. portae, through which blood flows into the liver through its gates,

kavalny, representing the totality of vv. hepaticae, carrying blood from the liver to v. cava inferior.

In the uterine period, a third, umbilical vein system functions; the latter are branches of v. umbilicalis, which becomes obliterated after birth.

As for the lymphatic vessels, there are no true lymphatic capillaries inside the liver lobules: they exist only in the interlobular connective tissue and flow into the plexus of lymphatic vessels accompanying the branches of the portal vein, hepatic artery and bile ducts, on the one hand, and the roots of the hepatic veins, on the other . The efferent lymphatic vessels of the liver go to the nodi hepatici, coeliaci, gastrici dextri, pylorici and to the peri-aortic nodes in the abdominal cavity, as well as to the phrenic and posterior mediastinal nodes (in the chest cavity). About half of the body's lymph is drained from the liver.

The liver is innervated from the celiac plexus through the truncus sympathicus and n. vagus

Segmental structure of the liver. In connection with the development of surgery and the development of hepatology, the doctrine of the segmental structure of the liver has now been created, which has changed the previous idea of ​​\u200b\u200bdividing the liver only into lobes and segments. As noted, the liver has five tubular systems:

Biliary tract,

Arteries,

Branches of the portal vein (portal system),

Hepatic veins (caval system)

Lymphatic vessels.

The portal and caval vein systems do not coincide with each other, and the remaining tubular systems accompany the branches of the portal vein, run parallel to each other and form vascular-secretory bundles, to which nerves are attached. Some of the lymphatic vessels exit along with the hepatic veins.

The role of the liver in the body cannot be overestimated. Its functions are wide and varied:

1) Participates in the process of food digestion, secreting bile.

2) Takes part in all types of metabolism (in carbohydrate metabolism - the formation and accumulation of glycogen, in fat metabolism - breaking down fats into fatty acids and ketone bodies with bile acids, also produces cholesterol and ensures the deposition of fat in the body).

3) Regulates the balance of proteins, fats and carbohydrates. If there is a lack of carbohydrates in food, it synthesizes them from protein; if there is an excess of carbohydrates and proteins in food, it processes the excess into fats.

4) Promotes the synthesis of hormones of the adrenal glands, pancreas and thyroid gland. It is involved in the synthesis of anticoagulants (substances that prevent blood clotting), the exchange of microelements by regulating the absorption and deposition of cobalt, iron, copper, zinc and manganese.

5)Protective function (barrier to toxic substances, blood purification, neutralization of all poisons that enter the body from the outside).

6) Control of the balance of homeostasis (constancy of the internal environment of the body) is ensured through the biotransformation of foreign compounds into water-soluble non-toxic substances that are excreted from the body by the intestines, kidneys and through the skin.

Liver diseases

The human body is designed in such a way that all organs can be divided into vital and auxiliary. The liver definitely belongs to the first group. Its importance for maintaining the vitality of the body cannot be overestimated. After all, it is a powerful parenchymal organ that combines the functions of the digestive gland and a kind of biochemical laboratory.

It is here that all the central biochemical reactions and processes responsible for maintaining life occur. Naturally, the more complex the structure of an organ and the higher the load on it, the more vulnerable it is. And despite the excellent regenerative and restoration abilities of the liver, the number of its diseases that develop into liver failure continues to grow steadily.

Let us highlight the following classes of liver diseases:

1) Congenital developmental anomalies.

2) Liver injuries:

Open damage.

Stab and cut wounds.

Gunshot wounds.

Closed liver injuries (ruptures).

Focal diseases.

3) Inflammatory diseases:

Nonspecific (abscesses).

Specific (tuberculosis, syphilis, etc.).

4) Liver tumors:

Benign tumors.

Malignant tumors.

Echinococcosis.

Alveococcosis.

Opisthorchiasis.

Ascariasis.

Diffuse diseases (cirrhosis), complications of which require surgical correction (portal hypertension).

Chronic hepatitis

Chronic hepatitis - chronic diffuse inflammatory process in the liver for more than 6 months.

Etiology

The disease is caused by acute viral hepatitis, alcohol abuse, dysfunction immune system(autoimmune reactions), exposure to certain medications (salicylates, tetracycline, anabolic steroids, tranquilizers, anticonvulsants).

Depending on the etiological factor, they are distinguished: chronic viral hepatitis B, C, D, chronic autoimmune hepatitis, chronic toxic hepatitis.