Nasal cavity pigs relative narrow, long and somewhat expanded at the ventral wall.
Apical movable part of the nose formed into a kind of proboscis (Fig. 358), closely connected from dorsal lip. It represents a rounded, segmented plane education. Round-oval nostrils open on its anterior free surface. The skin of the proboscis with short, very sparse sensitive (sinus) hairs, penetrated small pores of excretory ducts of the proboscis glands. The surface itself, the planum rostrale, is divided by grooves into clear fields.
The proboscis contains as a skeleton proboscis bone - os rostri - representing the ossified end of the relatively thick cartilaginous nasal septum. The proboscis bone is mobile and lies between the free ends of the nasal bones and the incisor bones. From the dorsal part of the proboscis to the right and left, curving downwards (Fig. 359- 2), cartilaginous plates extend to the lateral sides. They serve partly as a roof, partly as a side wall of the apical part of the right and left nasal cavities (corresponding to the alar plate of the pterygoid cartilages) and are adjacent to the dorsal lateral cartilages (4). The latter extend from the dorsal edge of the nasal septum
17 Anatomy of Pets
514 digestive system
and form the walls of the nasal cavity, joining the ventral side cartilages (5). From the ventral part of the proboscis to the right and left sides it continues along the cartilaginous horn (3). Each of them forms the basis of the lateral wing of the nose. The proboscis serves as a device for digging roots out of the ground.
The skin from the proboscis is wrapped inside the nasal cavity, for a short distance it lines the vestibule of the nose and passes
into the section of the nasal cavity itself, already covered with a mucous membrane with ciliated epithelium.
Cassock. 358. Proboscis. pigs. 1 -nostrils
The dorsal concha is long and narrow, the ventral concha is wider. A small dorsal nasal passage leads into the labyrinth; The middle nasal passage forms a deep gap between both shells and bifurcates in the area of the large internal curl (endoturbinale) of the olfactory labyrinth, with the dorsal branch ending in the labyrinth, and the ventral branch, expanding, merging with the ventral nasal passage. The latter is very voluminous and opens into relatively small but long oval choanae. The narrow nasopalatine canal connects the nasal cavity with the oral cavity. The lacrimal duct ends in the vestibule of the nose, often with two openings. The lateral nasal glands exist and open partly into the maxillary sinus, partly into the middle meatus near the entrance to the nose.
4 JL _
G 
ortagny relatively long (Fig. 360), built from easily interconnected cartilages of the skeleton (Fig. 345).
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Rice. 359. Nasal cartilages of pigs.
1 - proboscis bone; 2 -plate corresponding to the pterygoid cartilage; 3 -lateral horn; 4 -dorsal and 5 -ventral lateral cartilages.
Long thyroid cartilage (2) with its lateral plates it is fused ventrally throughout its entire length into the body, with the oral margin being slightly thickened; towards the trachea, both plates become higher. The amoral horns for connection with the annular cartilage are short and wide; the oral horns, and therefore the thyroid notch, are absent.
On the annular cartilage (1) bow in relation to the record (A) strongly inclined downwards and backwards.
Scoop prominent cartilage (3) have very
developed muscular crest and clearly protruding vocal process. The carotid cartilages (cartilagines corniculatae) curved upwards and backwards are especially strongly expressed. At their apex they are bifurcated, with their wide and long medial sections merging along the midsagittal plane into one unpaired formation. Near the annular cartilage, between the dorsomedial corners of the arytenoid cartilages, a small intermediate cartilage is inserted.
4) Epiglottic cartilage {4) wide, without wedge-shaped cartilages at the base and very weakly connected with the thyroid cartilage by a thin elastic thyroid-epiglottic ligament and mucous membrane; Hypoglossally, above the laryngeal medial ligament, it is connected to the body of the hyoid bone, and by lateral ligaments to its greater horns. At the free end, the epiglottis is rounded.
RESPIRATORY ORGANS OF DOGS
The vocal cord is bifurcated into a large anterior and smaller posterior portion, due to which the vocal fold of the mucous membrane breaks up into significant anterior and weaker posterior folds, and between them there remains a long notch, from which a small round hole leads into a large lateral laryngeal pocket. The vocal lips lie relatively close and parallel to each other, forming a narrow glottis. At the base of the epiglottis is the middle laryngeal pouch.
T 
Raeseya pigs is cylindrical and consists of 32-36 rings (Fig. 360-B). The ends of the rings on the dorsal side either overlap each other or barely touch. IN chest cavity, even before bifurcation, with
Rice. 360. Cartilages of the larynx of pigs.
1 - ring-shaped cartilage; 2 -thyroid cartilage; 3-arytenoid cartilages; 4 -epiglottis; 5, 6, 7- - tracheal rings; 5-large horns of the hyoid bone; 9 - her small horns; 10, 11, 12 - distal, middle and proximal segments of the hyoid bone; A-plate of annular cartilage; b, s- ligaments of the thyroid cartilage with the annular cartilage and the hyoid bone. IN- diagram of a transverse section of the trachea; tracheal d-ring.
Rice. 361. Lungs of pigs: A-from the left* IN-on the right side.
1 - apical lobe; 2 - cardiac lobe;
3-diaphragmatic share; A-blunt
edge; Kommersant-sharp edge; s-trachea.
the trachea, like in ruminants, gives off a special eparterial bronchus to the apical lobe of the right lung. Lungs pigs (Fig. 361) clearly lobed: on the right lung is distinguished by the apical lobe (1), delimited by a wide notch from the cardiac lobe (2), which is separated from the large diaphragmatic lobe (3) by a narrow and deep gap. There is an additional share. The left lung consists of lobes of the same number and name, with the exception, of course, of the additional lobe. A cellular pattern is noticeable on the surface of the lung, reflecting the nature of the structure of the organ from small lobules separated by layers of connective tissue; however, the pattern is not as prominent as that of cattle.
Nasal cavity pigs is relatively narrow, long and somewhat widened at the ventral wall.
The apical movable part of the nose is formed into a kind of proboscis (Fig. 358), closely connected with the dorsal lip. It represents a round formation placed in the segmental plane. On its anterior free surface, round-oval nostrils open. The skin of the proboscis with short, very sparse sensitive (sinus) hairs is penetrated by small pores of the excretory ducts of the proboscis glands. The surface itself, the planum rostrale, is divided by grooves into clear fields.
The proboscis as a skeleton encloses the proboscis bone - os rostri - representing the ossified end of the relatively thick cartilaginous nasal septum. The proboscis bone is mobile and lies between the free ends of the nasal bones and the incisor bones. From the dorsal part of the proboscis bone on the right and left, curving downwards (Fig. 359-2), cartilaginous plates extend to the lateral sides. They serve partly as a roof, partly as a side wall of the apical part of the right and left nasal cavities (corresponding to the alar plate of the pterygoid cartilages) and are adjacent to the dorsal lateral cartilages (4). The latter extend from the dorsal edge of the nasal septum and form the walls of the nasal cavity, joining the ventral lateral cartilages (5). From the ventral part of the proboscis to the right and left sides it continues along the cartilaginous horn (3). Each of them forms the basis of the lateral wing of the nose. The proboscis serves as a device for digging roots out of the ground.
The skin from the proboscis is wrapped inside the nasal cavity, lines the vestibule of the nose for a short distance and passes into the section of the nasal cavity itself, already covered with a mucous membrane with ciliated epithelium.
The dorsal concha is long and narrow, the ventral concha is wider. A small dorsal nasal passage leads into the labyrinth; The middle nasal passage forms a deep gap between both shells and bifurcates in the area of the large internal curl (endoturbinale) of the olfactory labyrinth, with the dorsal branch ending in the labyrinth, and the ventral branch, expanding, merging with the ventral nasal passage. The latter is very voluminous and opens into relatively small but long oval choanae.
The narrow nasopalatine canal connects the nasal cavity with the oral cavity. The lacrimal duct ends in the vestibule of the nose, often with two openings. The lateral nasal glands exist and open partly into the maxillary sinus, partly into the middle meatus not far from the entrance to the nose.
The larynx is relatively long (Fig. 360), built from easily interconnected cartilages of the skeleton (Fig. 345).
1) The long thyroid cartilage (2) with its lateral plates is ventrally fused throughout its entire length into the body, and the oral edge is “slightly thickened; towards the trachea, both plates become higher. The aboral horns for connection with the annular cartilage are short and wide; the oral horns, and therefore the thyroid notch, are absent.
2) On the annular cartilage (1), the arch in relation to the plate (a) is strongly inclined downward and backward.
3) The arytenoid cartilages (3) have a highly developed muscular crest and a clearly protruding vocal process. The carotid cartilages (cartilagines corniculatae) curved upward and backward are especially pronounced. At their apex they are bifurcated, with their wide and long medial sections merging along the midsagittal plane into one unpaired formation. Near the annular cartilage, between the dorsomedial corners of the arytenoid cartilages, a small intermediate cartilage is inserted.
4) The epiglottic cartilage (4) is wide, without wedge-shaped cartilages at the base and is very weakly connected to the thyroid cartilage by a thin elastic thyroid-epiglottic ligament and mucous membrane; It is connected by the hypoglottic medial ligament to the body of the hyoid bone, and by the lateral ligaments to its greater horns. At the free end, the epiglottis is rounded.
The vocal cord is bifurcated into a large anterior and smaller posterior portion, due to which the vocal fold of the mucous membrane breaks up into significant anterior and weaker posterior folds, and between them there remains a long notch, from which a small round hole leads into a large lateral laryngeal pocket. The vocal lips lie relatively close and parallel to each other, forming a narrow glottis. At the base of the epiglottis is the middle laryngeal pouch.
The vocalis and pouch muscles are fused together. The hypoglossal muscle is highly developed.
Trachea pigs is cylindrical and consists of 32-36 rings (Fig. 360-B). The ends of the rings on the dorsal side either overlap each other or barely touch.
IN chest cavity, even before the bifurcation,
the trachea, like in ruminants, gives off a special eparterial bronchus to the apical lobe of the right lung.
Pig lungs(Fig. 361) clearly lobulated: on the right lung there is an apical lobe (I), delimited by a wide notch from the cardiac lobe (2), which is separated from the large diaphragmatic lobe (3) by a narrow and deep fissure. There is an additional share. The left lung consists of lobes of the same number and name, with the exception, of course, of the additional lobe. A cellular pattern is noticeable on the surface of the lung, reflecting the nature of the structure of the organ from small lobules separated by layers of connective tissue; however, the pattern is not as prominent as that of cattle.
Anatomy is a science that studies the forms, structure, relationships and location of parts of the body, and physiology is a science that studies the processes (functions) occurring in a living organism and their patterns. The general data of these sciences will help you understand, for example, how to distinguish a sick animal from a healthy one and how to properly provide first veterinary aid to it.
The body of any animal is built from the smallest living particles - cells. Certain groups of cells, changing their shape and structure, unite into separate clusters that have adapted to perform certain functions. Such groups of cells, as a rule, have specific qualities and are called fabrics. There are 4 types of tissues in the body - epithelial, connective, muscle and nervous.
Epithelial tissue covers all border formations in the body - such as skin, mucous and serous membranes, excretory ducts of glands, endocrine and exocrine glands. It communicates the body with the external environment, performs integumentary, glandular (secretory) and absorption functions.
Connective tissue divided into feeding and supporting. Nutrient, or trophic, tissue includes blood and lymph. The main purpose of supporting tissue is to bind the component parts of the body into a single whole and to form the skeleton of the body (for example, this includes bone tissue, tendons, cartilage).
Muscle tissue capable of contraction and relaxation under the influence of various stimuli. It is divided into skeletal and cardiac muscles, which have cross-striations, as well as smooth muscle tissue, capable of involuntary contractions and found in internal organs.
Nervous tissue consists of nerve cells - neurons that have the property of excitation and conduction of nervous excitation, and neuroglial cells that perform supporting, trophic and protective functions.
Separate groups of tissues connect with each other and form organs . Authority They call a part of an organism that has a certain external shape, is built from several naturally combined tissues and performs a highly specific function. For example, an organ is called an eye, a kidney, a tongue.
Individual organs that together perform one specific function form in the body systems, or devices. For example, bones, muscles, ligaments, tendons, joints form a movement apparatus, or musculoskeletal system.
The organs of such animal body systems as the digestive, respiratory and genitourinary, i.e., internal organs, are located in 3 cavities: thoracic, abdominal and pelvic.
Thoracic cavity located inside the chest, abdominal in front it is limited by the diaphragm (thoracoperitoneal muscular barrier), and in the back it passes into the pelvic cavity. It is located between the thoracic and pelvic cavities, ending at the lumbar level. Pelvic cavity form the pelvic bones, the sacrum and the first caudal vertebrae.
Most internal organs located in serous cavities, which create conditions for organs to slide around each other. For example, the heart is located in the pericardial serous cavity.
A necessary condition for the existence of any animal organism is metabolism- a continuously occurring breakdown of the constituent parts of the body, accompanied by a restoration process with the help of an influx of food from the external environment. Metabolism and energy conversion in a living organism are inseparable from each other. The formation and release of heat depends primarily on metabolism. Thus, pigs are warm-blooded animals, i.e. their body temperature is relatively constant and under normal conditions is maintained, depending on age and physiological state, in piglets at 39.0-40.5 ° C, in adults – 38.5 -40.0 °C. Body temperature depends on climatic and other factors, but most of all changes under the influence of pathogenic microbes and viruses. It is measured using a medical or veterinary thermometer, inserting it into the rectum (rectally) to a depth of 7-10 cm. The thermometer is first shaken, lubricated with petroleum jelly, and the measurement itself is carried out for 10 minutes. You can attach a rubber tube to the thermometer to make it easy to pull out. The tube is attached to the animal's tail.
The body of pigs, like other animals, is conventionally divided into 4 main sections (Fig. 2).
Rice. 2.Stati pigs:1 – region of the occipital bone; 2 – region of the parietal bone; 3 – forehead; 4 – ear; 5 – temple; 6 – eyes and eyelids; 7 – cheeks; 8 – nose; 9 – nostrils; 10 – mouth (with trunk, or snout); 11 – chin area; 12 – back of the head; 13 – ridge; 14 – side of the neck; 15 – throat; 16 – withers; 17 – chest; 18 – back; 19 – belly, or belly; 20 – groin, or ileum; 21 – lower back; 22 – sacrum; 23 – maklok; 24 – tail root; 25 – tail; 26 – anus; 27 – anal perineum; 28 – large lips of female reproductive parts; 29 – loop; 30 – udder (31 – in hogs the moth is with schulyats and foreskin); 32 – shoulder; 33 – forearm; 34 – elbow; 35 – front knee; 36 – ankle; 37 – tibia-paternal joint; 38 – grandmother; 39 – corolla; 40 – hoof; 41 – ham; 42 – shin; 43 – knee joint; 44 – hock joint; 45 – heel
Head. It distinguishes between the brain (skull) and facial (muzzle) parts. This includes the forehead, nose, ears, teeth.
Neck. Here the neck area and the jugular groove area are distinguished (it is located above the trachea, where the jugular veins pass).
Torso. It is represented by the withers (it is formed by the first 5 thoracic vertebrae and the upper edges of the scapula located at the same level with them), back, lower back, thoracic region (chest), dewlap, croup, right and left iliac region, right and left groin, umbilical region, area of the udder, or mammary gland, and prepuce, anal area, tail.
Limbs. The thoracic (front) limb is represented by the shoulder, elbow, forearm, wrist, metacarpus, and the pelvic (back) limb is represented by the thigh, knee, lower leg, heel, and metatarsus.
The appearance of an animal, physique and characteristics of individual parts of its body, characteristic of its breed and gender, are called exterior. The general exterior includes the main features of the physique, the structure of individual parts of the body, the most characteristic deviations and defects, the private one considers the features of the build individual breeds, typical and atypical signs for them. The exterior of animals indicates their breed and the degree of expression of the breed. Pigs are distinguished by very specific body features, and such seemingly insignificant indicators of the animal’s exterior, such as the structure of the snout, the setting and shape of the ears, are quite stable breed characteristics. Well-developed breeding pigs have a relatively small head with a slightly concave snout and rather large ears, a relatively short but thick neck, an elongated, well-developed body with rounded shapes, a relatively short legs with well-muscled hams. Sows have a well-developed abdomen and at least 12 teats. The hair (bristles), as well as the skin of cultivated breeds, in comparison with natural ones, is always much weaker and thinner. The exterior features of pigs depend on their production type, breed, age and gender.
The exterior determines the direction of the animal’s productivity, its state of health and the degree of adaptability to environmental conditions. The exterior is an external reflection of the interior. Interior call a set of internal features, physiological, biochemical and anatomical-histological properties of the body in connection with the constitution, exterior and direction of productivity. Studying the interior makes it possible to compare the development of organs and tissues with the peculiarities of the flow of physiological and biochemical processes in the animal’s body. For example, in cultivated breeds of pigs the concentration of insulin and sugar in the blood is higher compared to natural ones.
The concept " constitution“combines all the properties of the animal’s body: features of its anatomical structure, physiological processes and, above all, features of higher nervous activity that determine reactions to the external environment. In animal husbandry, there are 5 types of constitution: coarse (natural breeds of pigs), tender (bacon and meat breeds), dense or dry (meat breeds), loose or raw (greasy breeds of pigs). A certain predisposition to certain diseases is also closely related to the constitution. For example, animals with a delicate constitution are predisposed to tuberculosis, and animals with a loose constitution are predisposed to diseases of the gastrointestinal tract.
When determining the constitution of pigs and assessing the exterior, the condition is determined. Condition- this is the general appearance of the animal, external signs, fatness, condition of muscles, skin, which helps determine whether the animal is healthy or sick. There are factory, exhibition, fattening and starvation conditions.
Movement apparatus, or musculoskeletal system
The movement apparatus is represented by the skeleton, ligaments and muscles, which, unlike other systems, form the physique of pigs and their exterior. To imagine its significance, it is enough to know that in newborns the movement apparatus accounts for approximately 70-78% of the total mass of the animal, and in adults – up to 60-68%. In phylogenesis, departments of different importance are formed: the skeleton as a supporting structure, ligaments that connect bones, and skeletal muscles that move bone levers.
Bone- part of the skeleton, an organ that consists of different tissue elements. These are 6 components, one of which is red bone marrow - a hematopoietic organ. Red bone marrow is stored longest in the spongy substance of the sternum and vertebral bodies. All veins (up to 50% of the veins of the whole body) leave the bones mainly where there is more spongy substance. Through these areas, intraosseous injections are made, which replace intravenous ones.
Skeleton pigs, like other farm animals, consists of two sections: axial and peripheral (Fig. 3).
Rice. 3. Pig Skeleton:1 – nasal bone; 2 – frontal bone; 3 – occipital bone; 4 – atlas; 5 – crest of the second cervical vertebra; 6 – first thoracic vertebra (its spinous process); 7 – shoulder blade; 8 – fourteenth thoracic vertebra; 9 – first and 10 – seventh lumbar vertebrae; 11 – sacral bone; 12 – caudal vertebrae; 13 – lower jaw; 14 – jugular process; 15 – transverse costal process of the sixth vertebra; 16 – humerus; 17 – bones of the forearm; 18 – wrist; 19 – metacarpus; 20 – phalanges of fingers; 21 – chest bone; 22 – ribs; 23 – ilium of the pelvis; 24 – ischium; 25 – femur; 26 – tibia; 27 – fibula; 28 – tarsus; 29 – metatarsus; 30 – phalanges of fingers
The axial section of the skeleton is represented by the skull, spine and rib cage.
The skull, or skeleton of the head, is divided into the brain part (7 bones) and the facial part (13 bones). The bones of the cranium form the sheath for the brain, and the bones facial section– oral and nasal cavities and eye orbits; V temporal bone the organs of hearing and balance are located. The bones of the skull are connected by sutures, except for the movable ones - the lower jaw, temporal and hyoid bones. Pigs have a massive, heavy and different shapes depending on the breed. The main feature of the skull is the presence of a proboscis bone (Fig. 4), which developed in connection with the peculiarities of obtaining food by wild ancestors (digging the earth, tearing off tree roots).
Rice. 4. Pig Skull:1 – incisor bone; 2 – nasal bone; 3 – maxillary bone; 4 – lacrimal bone; 5 – zygomatic bone; 6 – orbit; 7 – frontal bone; 8 – parietal bone; 9 – temporal bone; 10 – occipital bone; 11 – lower jaw; 12 – proboscis bone
Along the body of the animal there is a spine, in which there is a spinal column formed by the vertebral bodies (the supporting part that connects the work of the limbs in the form of a kinematic arc), and the spinal canal, which is formed by the vertebral arches surrounding the spinal cord. Depending on the mechanical load created by body weight and mobility, the vertebrae have different shape and size.
The spine is differentiated into sections that coincide with the direction of the animal's gravity: cervical, thoracic, lumbar, sacral, caudal (Table 1).
Table 1Number of vertebrae in a pig(Divisions of the spine)Cervical – ( Number of vertebrae) 7
Chest– 14-16
Lumbar– 6-7
Sacral– 4
Tail– 20-22
Total– 52-55
The long, laterally compressed chest is formed by the ribs (usually 14 pairs) and the breastbone. It contains the heart and lungs. The ribs are paired arched bones that are movably attached on the right and left to the vertebrae of the thoracic spinal column. They are less mobile in the front of the chest, where the shoulder blades are attached to them. In this regard, the anterior lobes of the lungs are more often affected by organ disease.
The peripheral skeleton, or skeleton of the limbs, is represented by two thoracic (front) and two pelvic (hind) limbs, which perform the function of movement in space. Pigs can not only move on land, but also swim.
The thoracic limb includes a scapula, attached to the body in the area of the first ribs; shoulder consisting of humerus; the forearm, represented by the radius and ulna bones; hand, consisting of the wrist, metacarpus and phalanges of the fingers.
Pigs have short limbs with 4 fingers, of which only the middle 2 (third and fourth) rest on the ground. Both side toes (second and fifth) do not touch the ground. Each finger has 3 phalanges, with the third phalanx called the coffin bone (Fig. 5).
Rice. 5. Pig hand skeleton:1 – radius; 2 – ulna; 3 – carpal bones; 4 – metacarpal bones; 5 – phalanges of fingers
The pelvic limb consists of a pelvis, each half of which is made up of an innominate bone. The ilium is located at the top, the pubic and ischium bones are located below, the femur is represented by femur and the kneecap, which slides along the femur block; lower leg, consisting of the tibia and fibula; the foot, represented by the tarsus, metatarsus and phalanges of 4 fingers, of which only the middle two (third and fourth) rest on the ground. Both side toes (second and fifth) do not touch the ground. The third phalanx of each finger is called the coffin bone.
Ligaments- These are bundles of collagen fibers that connect bones or cartilage to each other. They experience the same body mass load as the bones, but by connecting the bones to each other, the ligaments provide the necessary buffering to the skeleton, which significantly increases the resistance to the loads placed on the bone joints as supporting structures.
There are 2 types of bone connections:
› continuous. This type of connection has great elasticity, strength and very limited mobility (for example, skull bones);
› discontinuous (synovial) type of connection, or joints. It allows for a greater range of motion and is built more complexly (eg, limb bones). The joint has an articular capsule consisting of 2 layers - the outer layer (fused with the periosteum of the bone) and the inner layer (synovial layer, which secretes synovium into the joint cavity, thanks to which the bones do not rub against each other). Most joints, except for the capsule, are secured by a different number of ligaments. When ligaments are torn or severely sprained, the bones separate from each other and the joint dislocates.
Among diseases of the organs of the movement apparatus, pathological processes at the junctions of bones, especially the joints of the limbs, are more common than others. Pathologies at the junctions of bones have dangerous consequences such as loss of mobility, which is accompanied by loss of the ability to move normally and significant pain.
Muscle tissue has an important property - to contract, causing movement (dynamic work), and ensures the tone of the muscles themselves, strengthening the joints at a certain angle of combination with a stationary body (static work). Only work (training) of muscles helps to increase their mass, both by increasing the diameter of muscle fibers (hypertrophy) and by increasing their number (hyperplasia).
Each muscle has a supporting part (connective tissue stroma) and a working part (muscle parenchyma). The more static work a muscle performs, the more developed its stroma is.
There are three types of muscle tissue depending on the location of the muscle fibers: smooth (vascular walls), striated (skeletal muscles), cardiac striated (in the heart). According to the nature of their activity and the work performed, they are divided into flexion and extension, adduction and abduction, locking (sphincters), rotating, etc. The work of the muscular apparatus is based on the principle of antagonism.
In total, there are up to 200-250 paired muscles and several unpaired muscles in the body.
Totality skeletal muscles with ligaments, muscle sheaths, vessels, nerves and bones forms pig meat, or pork. Pork is light meat, because the muscles are less saturated with myoglobin and sarcoplasm due to the lack of heavy loads, and the meat on the limbs is darker than on the body.
Skin
The body of pigs is covered with hairy skin and organs or derivatives of the skin. Their appearance, consistency, temperature and sensitivity reflect the state of metabolism and the functioning of a number of organ systems.
Leather protects the body from external influences, through many nerve endings acting as a receptor link for the skin analyzer of the external environment (tactile, pain, temperature sensitivity). Through many sweat and sebaceous glands it releases a number of metabolic products, through the mouths of the hair follicles and skin glands the surface of the skin can absorb small amounts of solutions. The blood vessels of the skin can hold up to 10% of the animal's body's blood, so this organ is a blood depot. The constriction and dilation of blood vessels plays a significant role in the regulation of body temperature (about 82% of all heat loss in the body occurs through the skin surface).
Rice. 6. Structure of pig skin:a – epidermis; b – dermis; c – subcutaneous layer (base of the skin); d – subepidermal papillary sublayer: 1 – sebaceous gland; 2 – sweat gland; 3 – bristles; 4 – adipose tissue in the dermis
In pig skin covered with hair, the following layers are distinguished (Fig. 6):
›periocutum (epidermis) – the outer layer that determines the color of the skin. Dead cells are peeled off, thereby removing dirt and microorganisms from the surface of the skin. Hair grows here;
› dermis (the skin itself), where there are sebaceous and sweat glands, many blood and lymphatic vessels and nerve endings, nests of loose and fatty connective tissue;
› subcutaneous base (subcutaneous layer), represented by loose connective and adipose tissue. This layer is attached to the superficial fascia covering the body. This is where the bristle bulbs are located. IN subcutaneous layer spare parts are put aside nutrients in the form of fat that forms a layer of lard known as bacon. The skin with hair and subcutaneous tissue removed from the body of an animal is called a hide.
In some areas of the body, pig skin has significant structural features. For example, in boars, the skin on the lateral surface of the shoulder and chest is thickened, and there is a so-called shield in it in the form of a layer of dense connective tissue with layers of fat.
TO derivative of the skin pigs include sweat, sebaceous and mammary glands, as well as hooves, pulp, hair and proboscis.
Sebaceous glands located at the base of the skin over the entire surface of the body, and their ducts open into the mouths of the hair follicles. The sebaceous glands secrete a sebaceous secretion, which, lubricating the skin and hair, gives it softness and elasticity, protects it from fragility, and the body from moisture.
Sweat glands located in the reticular layer of skin over the entire surface of the body. Their excretory ducts open to the surface of the epidermis, through which a liquid secretion is released - sweat containing a significant amount of protein, cholesterol, and particles of the cytoplasm of secreting cells. Sweat has a specific smell characteristic of pigs.
There are tens of times fewer sebaceous and sweat glands in the skin of pigs than in the skin of cattle, horses and sheep. There are quite a lot of them in the chin area and in the folds of skin on the surface of the wrist joints. The secretion of glands is interconnected with the reproductive cycle of animals.
Breast. The mammary gland of farm animals is called the udder. Pigs have multiple udders, consisting of 6-8 pairs of mammary glands lying on the sides of the white line from the xiphoid cartilage to the pubic region (Fig. 7).
Rice. 7. Pig mammary gland:1 – chest; 2 – abdominal; 3 – inguinal nipples
Based on their location, the glands are distinguished between the pectoral, abdominal and inguinal glands. Each mammary gland rises in the form of a hill with a nipple. Each milk hill has 2, rarely 3 lobes. Inside the udder there are alveoli (milk is formed in them), lined from the inside with secretory epithelium. The alveoli become the milk ducts. The latter open into a small tank, from which they go to the tip of the nipple nipple canals. Sphincters (muscle rings that prevent milk from spilling out) in the nipple canals are underdeveloped. In most pigs, each teat has 2-3 canals corresponding to the number of lobes in the mammary mound. The thoracic and abdominal mounds of the mammary glands are often more developed than the inguinal ones and secrete more milk.
The main function of the mammary gland is the formation and accumulation of milk (liquid secreted by the mammary gland of mammals 5-7 days after birth and necessary for feeding the baby) with its periodic excretion during sucking or milking, i.e. lactation (Table 2). Milk secretion is a complex reflex process associated with consistent structural and functional changes in glandular cells and various tissues of the mammary gland. The duration of the lactation period (the time from the moment of birth until the cessation of milk secretion) depends on the breed, feeding and maintenance of animals, the timing of a new pregnancy, etc. In pigs, it is 2 months after birth or more.
Table 2Composition of milk from a pig, cow, goat, mare (average values)
However, pigs often experience a small secretion of milk after birth - hypogalactia. If milk is not produced at all, they speak of agalactia. The cause of these phenomena may be a violation of the endocrine activity of the pituitary gland, ovaries, adrenal glands and other endocrine glands, insufficient development of glandular tissue of the mammary gland as a result of protein starvation of the sow, obesity of sows during pregnancy due to overfeeding with carbohydrate feeds, infectious agents (mastitis, vaginitis, metritis, birth sepsis). Most often this is observed in first mothers as a result of prolonged labor. If these symptoms are not noticed in time, then by 3-5 days after birth there will be a large loss of newborn piglets. To prevent hypogalactia and agalactia, it is necessary to introduce dairy feed into the diet of sows (whey, skim milk, beets, carrots, etc.), and sick individuals should be treated as prescribed by a veterinary specialist.
Hooves. These are hard skin tips of the 3rd phalanx of the third and fourth digits of artiodactyls, protecting the end of the digit from damage. The hoof is represented by a section of skin, the epidermis of which in certain places produces horny layers of varying structure and consistency. Based on the location and nature of the stratum corneum produced on the hoof, 4 parts are distinguished: border, corolla, wall and sole (Fig. 8). The hoof border is a narrow strip at the border between the hairy skin and the underlying hoof crown. The producing layer of the epidermis of the border produces a soft, colorless stratum corneum that gives shine to the claw, a glaze that covers the underlying layer formed by the corolla. The hoof corolla is located below the border in a wide ridge (approximately 1/2 of a hoof in height). The productive layer of the epidermis produces a powerful, hard, pigmented tubular horn that grows down and covers the wall of the hoof. The hoof wall, the most massive part of the hooves, covers the claw bone and fuses with the periosteum. The productive layer of the epidermis produces a soft, colorless leaf-shaped horn, fused with the inner surface of the tubular horn. The terminal portion of the latter forms an insensitive white zone, showing the boundary between the tubular and plantar horn. The sole of the hoof is a concave plate located on the undersurface of the hoof. The productive layer of the epidermis of the sole produces a soft, easily cut plantar horn with a knife (this is important for trimming the claw). The glaze, tubular, lamellar and plantar horn form the horn capsule, or shoe, covering the underlying layers of the skin of the hoof. It distinguishes the wall of the horny capsule, the plantar edge and the sole.
Rice. 8. Base of skin (dermis) of the claw:a – inner side; b – outer side: 1 – border; 2 – corolla with papillae; 3 – side wall of the claw with leaves; 4 – sole; 5 – crumb
Crumbs. These are the supporting areas of the limbs located behind the hooves. They are rich in nerve endings, due to which they act as an organ of touch. The sole layer also forms a cushion of crumb, softening the impact of the toes on the ground.
On the limbs of the pig there are 2 supporting and 2 hanging fingers, they have hooves and crumbs (Fig. 9).
Rice. 9. Hooves and crumbs of pig fingers from the back surface:1, 1? – soles of the third and fourth supporting fingers; 2, 2? – the crumbs of these fingers; 3, 3? – hooves and crumbs of the second and fifth hanging fingers; 4 – interclaw gap
Hair. The body of all animals is covered with fur. Hair is a spindle-shaped filament of stratified keratinized and keratinized epithelium. The part of the hair that rises above the surface of the skin is called the shaft, the part located inside the skin is called the root, it is surrounded by capillaries. The root passes into the bulb, inside of which there is a hair papilla. Each hair has its own muscles that allow it to straighten, as well as sebaceous glands.
In pigs, according to their structure, there are 4 main types of hair: guard hair (short outer hair of the body and long hair of the bangs, mane, as well as at the end of the tail and brushes), downy hair (hair around the guard hairs, covered by them), for example on the ears, transitional and vibrissae, or sensitive hair (hair on the skin around the lips, nostrils, chin and eyelids).
A significant part of the skin of pigs is covered with guard hairs - bristles. The bristle differs from other guard hairs in that its shaft has an apex split into horny threads. A split vertex is called a flag. In the skin, the stubble is located in groups consisting of several follicles. Her bulbs lie in subcutaneous tissue unlike other hair, the bulbs of which lie in the dermis.
Pigs, like other animals, undergo a change of body covering, or molting. In this case, the hair or fur coat is completely or partially replaced (except for tactile hairs). When molting, the skin thickens, becomes looser, and the stratum corneum of the epidermis is often renewed.
There are physiological and pathological molting. Physiological coat change is divided into 3 types: age-related (primary soft hair is replaced by coarser spinous hair), seasonal (spring and autumn) and compensatory (hair formation at the site of hair damage or destruction).
The bristles of pigs are not replaced simultaneously, but alternately: each hair lives for several years, and then, for example, after 2-3 years, it is replaced by a new one. Pathological shedding– this is an unmotivated change of hair as a result of illness, incorrect conditions feeding or keeping the animal.
Nervous system
The nervous system carries out the morphofunctional integration of parts of the body, the unity of the body and the environment, and also ensures the regulation of all types of body activity (movement, breathing, digestion, reproduction, blood and lymph circulation), as well as metabolism and energy.
The structural and functional unit of the nervous system is the nerve cell - neurocyte– together with gliocytes. The latter dress the nerve cells and provide them with support-trophic and barrier functions. Nerve cells have several processes - sensitive tree-like branching dendrites, which conduct to the body of the neuron the excitation that occurs at their sensitive nerve endings located in the organs, and one motor axon, along which the nerve impulse is transmitted from the neuron to the working organ or another neuron. Neurons come into contact with each other using the ends of their processes, forming reflex circuits through which nerve impulses are transmitted (propagated).
The processes of nerve cells together with neuroglial cells form nerve fibers. These fibers in the brain and spinal cord make up the bulk of white matter. From the processes of nerve cells, bundles are formed, from groups of which, covered by a common membrane, are formed nerve in the form of cord-like formations.
Anatomically, the nervous system is divided into central, including the brain and spinal cord with the spinal ganglia, and peripheral, consisting of cranial and spinal nerves connecting the central nervous system with receptors and effector apparatus various organs. This includes the nerves of skeletal muscles and skin - the somatic part of the nervous system - and blood vessels - the parasympathetic. These last two parts are united by the concept of “autonomous, or autonomic, nervous system.”
Central nervous system. Brain– head part central department nervous system. It is located in the cranial cavity and is represented by two hemispheres with convolutions separated by a groove. The brain is covered with a cortex, or cortex. Its weight in a pig ranges from 95-145 g.
The brain is divided into the following sections: cerebrum; telencephalon (olfactory brain and mantle); diencephalon (visual thalamus (thalamus), suprathalamus (epithalamus), subthalamus (hypothalamus), peritothalamus (metathalamus)); midbrain (cerebral peduncles and quadrigeminal); rhombencephalon; hindbrain (cerebellum and pons); medulla oblongata. They are all responsible for different functions. Almost all parts of the brain take part in the regulation of autonomic functions (metabolism, blood circulation, respiration, digestion), in medulla oblongata the centers of breathing and blood circulation are located, the cerebellum coordinates movements, maintains muscle tone and balance of the body in space. The main elementary manifestation of brain activity is a reflex (the body’s response to irritation of receptors), i.e., obtaining information about the result of a completed action.
The brain is covered with 3 membranes: hard, arachnoid and soft. Between hard and arachnoid membranes there is a subdural space filled with cerebrospinal fluid (its outflow into the venous system and lymph circulatory organs is possible), and between the arachnoid and soft - the subarachnoid space. The brain consists of white matter (nerve fibers) and gray matter (neurons). The gray matter in it is located on the periphery of the cerebral cortex, and the white matter is in the center.
The brain is the highest department of the nervous system, controlling the activity of the entire body; it unites and coordinates the functions of all internal organs and systems. In case of pathology (trauma, tumor, inflammation), the functions of the entire brain are disrupted, which is expressed in impaired movement, changes in the functioning of internal organs, disturbances in the animal’s behavior, and a comatose state (lack of the animal’s response to environmental influences).
Spinal cord- part of the central part of the nervous system, which is a cord of brain tissue with the remains of the brain cavity. The spinal cord is located in the spinal canal, it starts from the medulla oblongata and ends in the region of the 7th lumbar vertebra. Its length in a pig ranges from 119-139 cm, and its weight is approximately 70 g, i.e. 40% of the mass of the brain. The spinal cord is conventionally divided without visible boundaries into the cervical, thoracic and lumbosacral sections, consisting of gray and white brain matter. In the gray matter there are a number of somatic nerve centers that carry out various unconditioned (innate) reflexes. Thus, at the level of the lumbar segments there are centers innervating the pelvic limbs and the abdominal wall. The gray matter is located in the center of the spinal cord and is shaped like the letter “H”, while the white matter is located around the gray matter.
The spinal cord is covered with 3 protective membranes: hard, arachnoid and soft, between which there are gaps filled with cerebrospinal fluid. Into the cerebrospinal fluid and subdural space veterinary specialists Depending on the indications, injections may be given.
Peripheral nervous system- a topographically distinguished part of the unified nervous system, which is located outside the brain and spinal cord. This section includes cranial and spinal nerves with their roots, plexuses, ganglia and nerve endings embedded in organs and tissues. So, 31 pairs depart from the spinal cord peripheral nerves, and from the head - 12 pairs.
In the peripheral nervous system, it is customary to distinguish 4 parts - somatic (connecting centers with skeletal muscles), sympathetic (associated with the smooth muscles of the blood vessels of the body and internal organs), visceral, or parasympathetic (associated with smooth muscles and glands of internal organs), and trophic (innervating connective tissue).
Autonomic nervous system has special centers in the spinal cord and brain, as well as a number of nerve nodes located outside the spinal cord and brain. This part of the nervous system is divided into:
› sympathetic (innervation of smooth muscles of blood vessels, internal organs, glands), the centers of which are located in the thoracolumbar region of the spinal cord;
› parasympathetic (innervation of the pupil, salivary and lacrimal glands, respiratory organs, organs located in the pelvic cavity), whose centers are located in the brain.
The peculiarity of these two parts is the antagonistic nature of their provision of internal organs, i.e. where the sympathetic nervous system acts excitatory, the parasympathetic has an inhibitory effect.
The central nervous system and the cerebral cortex regulate the entire higher nervous activity animal through reflexes. There are genetically fixed reactions of the central nervous system to external and internal stimuli - food, sexual, defensive, orientation, sucking reaction in newborns, the appearance of saliva at the sight of food. These reactions are called innate, or unconditioned, reflexes. They are provided by the activity of the brain, the spinal cord stem, and the autonomic nervous system.
Conditioned reflexes are acquired individual adaptive reactions of animals that arise on the basis of the formation of a temporary connection between a stimulus and an unconditioned reflex act.
Pigs have an excellent memory, for example, they can be taught to open a door, perform certain commands, which allows them to be trained to perform various tricks, and when they are evicted from home, if they get the opportunity to escape from a new place, they return to the old place even from afar, and swim across the rivers they meet along the way.
Sense organs or analyzers
Excitation coming from the external environment and from the internal organs of the animal is perceived by the senses and then analyzed in the cerebral cortex.
An animal’s body has 5 sense organs: olfactory, gustatory, tactile, visual and equilibrium-auditory analyzers. Each of these organs has sections: peripheral (perceiving) - receptor, middle (conducting) - conductor, analyzing (in the cerebral cortex) - brain center. Analyzers, in addition to general properties (excitability, reactive sensitivity, aftereffect, adaptation and the phenomenon of contrast), perceive a certain type of impulses - light, sound, thermal, chemical, temperature, etc.
Smell– the ability of animals to perceive a certain property (smell) of chemical compounds in the environment. Molecules of odorous substances, which are signals of certain objects or events in the external environment, reach the olfactory cells along with the air when they are inhaled through the nose (during eating - through the choanae).
The olfactory organ is a small area located in the depths of the nasal cavity, namely in the common nasal passage, in its upper part, lined with the olfactory epithelium, in which receptor cells are located. Olfactory epithelial cells are the beginning olfactory nerves, through which excitation is transmitted to the brain. Between them are supporting cells producing mucus. On the surface of the receptor cells there are 10-12 hairs that react to aromatic molecules.
Pigs have a very sensitive sense of smell. They are able to detect odors that are inaccessible to humans, for example, by smell, these animals are able to find truffles, roots, and groundnuts in the ground. Wild pigs are very picky about what they eat.
Taste– quality analysis various substances entering the oral cavity. The sensation of taste arises as a result of exposure to solutions chemicals on the chemoreceptors of the taste buds of the tongue and oral mucosa. This creates a sensation of bitter, sour, salty, sweet or mixed taste. The sense of taste in newborns awakens before all other sensations.
Taste buds contain taste buds with neuroepithelial cells and are located mostly on the upper surface of the tongue, as well as in the oral mucosa. They come in three types in shape: mushroom-shaped, roll-shaped and leaf-shaped. On the outside, the taste bud is in contact with food substances; its other end is immersed in the thickness of the tongue and connected with nerve fibers. Taste buds do not live long, then they die and are replaced by new ones. They are unevenly distributed over the surface of the tongue, in groups, and form taste zones that are sensitive to substances with a certain taste.
Touch– the ability of animals to perceive various external influences (touch, pressure, stretching, cold, heat). It is carried out by receptors of the skin, musculoskeletal system (muscles, tendons and joints), mucous membranes (lips, tongue, etc.). Thus, the most sensitive skin is in the area of the hoof, eyelids, lips, as well as the back and forehead. The tactile sensation can be diverse, since it arises as a result of the complex perception of the various properties of the stimulus acting on the skin and subcutaneous tissues. Through touch, the shape, size, temperature and consistency of the stimulus, the position and movement of the body in space are determined. The basis of touch is the irritation of special structures - mechanoreceptors, thermoreceptors, pain receptors - and the transformation of incoming signals in the central nervous system into the appropriate type of sensitivity (tactile, temperature, pain or nociceptive).
Vision– the body’s ability to perceive objects in the external world by capturing emitted or reflected light. It allows, based on an analysis of the physical phenomena of the surrounding world, to organize purposeful vision. The process of vision in vertebrates is based on photoreception - the perception of light by the photoreceptors of the retina (see Organ of vision).
Hearing– the ability of animals to perceive and analyze sound vibrations of the environment, which is carried out when they are received through the auricle and external auditory canal (see Equilibrium-auditory organ).
Organ of vision, or visual analyzer
The organ of vision is represented by the eye. It consists of the eyeball, connected through the optic nerve to the brain, and auxiliary organs. The eyeball itself has a spherical shape and is located in a bony cavity - the orbit, or orbit, formed by the bones of the skull. The anterior pole is convex, and the posterior one is somewhat flattened (Fig. 10).
Rice. 10. Diagram of the structure of the eye (horizontal section):1 – anterior chamber; 2 – iris; 3 – cornea; 4 – conjunctiva; 5 – Schlemm’s canal; 6 – ciliary muscle; 7 – sclera; 8 – choroid; 9 – yellow spot; 10 – optic nerve; 11 – cribriform plate; 12 – ciliary body; 13 – rear camera; 14 – lens; 15 – ciliary processes; 16 – lens space; 17 – opical axis; 18 – Regina; 19 – optic nerve nipple; 20 – ligaments of Zinn; 21 – visual axis; 22 – vitreous body; 23 – central fossa
The eyeball consists of outer, middle and inner membranes, light-refracting media, nerves and blood vessels.
Outer or fibrous membrane It is divided into the albuginea, or sclera, and the cornea.
The tunica albuginea, or sclera, is a hard substance that covers 4/5 of the eyeball, with the exception of the anterior pole. It plays the role of a strong skeleton of the eye wall; the tendons of the eye muscles are attached to it.
The cornea is a transparent, dense and rather thick shell. It contains many nerves, but has no blood vessels, is involved in transmitting light to the retina, and responds to pain and pressure.
The middle, or choroid, membrane consists of the iris, ciliary body and the choroid itself.
The iris is the pigmented anterior part of the middle shell; in its central part there is a hole - the pupil. In pigs in daylight it has a round shape. Smooth muscle tissue forms 2 muscles in the iris - the sphincter (circular) and the dilator of the pupil (radial), thereby, by expanding or contracting, the pupil regulates the flow of light rays into the eyeball.
The ciliary body is a thickened part of the middle shell; it is located in the form of a ring up to 10 mm wide along the periphery of the posterior surface of the iris between it and the choroid itself. Its main part is the ciliary muscle, to which the ligament of Zinn (lens) is attached, which supports the lens capsule; under the action of this muscle, the lens becomes more or less convex.
Choroid - rear end middle shell of the eyeball. It is distinguished by an abundance of blood vessels and is located between the sclera and the retina, providing nutrition to the latter.
The inner layer, or retina, has a back and a front part.
The posterior part is the visual part, it lines most of the wall of the eyeball, where light stimuli are perceived and converted into a nerve signal. It consists of a nervous (internal, photosensitive, facing the vitreous) and pigment (outer, adjacent to the choroid) layers. In the nerve layer there are photoreceptor, primary sensory nerve cells of two types, with projections of different shapes - rods (receptors for twilight vision, providing black-and-white perception) and cones (receptors for daytime vision, providing color vision).
The anterior part is blind, covering the inside of the ciliary body and the iris, with which it fuses. It consists of pigment cells and lacks a photosensitive layer.
The cavity of the eyeball is filled with light-refracting media - the lens and the contents of the anterior, posterior and vitreous chambers of the eye.
The anterior chamber of the eye is the space between the cornea and the iris, the posterior chamber is the space between the iris and the lens. Both chambers are filled with chamber fluid. This liquid nourishes the tissues of the eye, removes waste products, and conducts light rays from the cornea to the lens.
Lens- a dense transparent body, shaped like a biconvex lens (changing its surface) and located between the iris and vitreous. This is the organ of accommodation. With age, the lens becomes less elastic.
Vitreous chamber- the space between the lens and the retina of the eye, which is filled with the vitreous humor (a transparent, gelatinous mass consisting of 98% water). Its functions are maintaining the shape and tone of the eyeball, conducting light and participating in intraocular metabolism.
Accessory organs of the eye– eyelids, lacrimal apparatus, eye muscles, orbit, periorbita and fascia.
Eyelids– skin-mucosal folds. They are located in front of the eyeball and protect the eyes from mechanical damage. Pigs have no eyelashes on their lower eyelids. The front part of the eyeball to the cornea and the inner surface of the eyelids are covered with a mucous membrane - the conjunctiva. There is also a third eyelid, or nictitating membrane. It is a semilunar fold of the conjunctiva. The third eyelid is located in the inner corner of the eye.
Lacrimal apparatus- lacrimal glands, canaliculi, lacrimal sac and nasolacrimal duct. In the inner corner of the eye there is a slight thickening of the conjunctiva - a lacrimal tubercle with a lacrimal canaliculus in the center, around which there is a small depression - a lacrimal lake. The tear secretion consists mainly of water and contains the enzyme lysozyme, which has a bactericidal effect. As the eyelids move, the tear fluid moisturizes and cleanses the conjunctiva and collects into the lacrimal lake. From here the secretion enters the tear ducts, which open in the inner corner of the eye. Through them, tears enter the nasolacrimal duct.
The location of the eyeball is called the orbit, and the periorbita is the area where the back of the eyeball, optic nerve, muscles, fascia, blood vessels and nerves are located. There are seven eye muscles, they are located inside the periorbita. They provide movement of the eyeball in different directions within the orbit.
Pigs have small eyes and binocular vision, that is, they see objects with both eyes, but it is weak.
Equilibrium-auditory organ, or statoacoustic analyzer
The statoacoustic analyzer consists of receptors of the vestibulocochlear organ, pathways and brain centers. The vestibulocochlear organ, or ear, is a complex set of structures that provide the perception of sound, vibration and gravitational signals. The receptors that perceive these signals are located in the membranous vestibule and the membranous cochlea, which determined the name of the organ (Fig. 11).
Rice. 11. Diagram of the organs of balance and hearing:
1 – auricle; 2 – external auditory canal; 3 – eardrum; 4 – hammer; 5 – anvil; 6 – stapedius muscle; 7 – stirrup; 8 – semicircular canals; 9 – oval pouch; 10 – equilibrium spot and equilibrium ridges; 11 – endolithmatic duct and sac in the aqueduct of the vestibule; 12 – round sac with an equilibrium spot; 13 – cochlear arch; 14 – membranous cochlea; 15 – organ of Corti; 16 – scala tympani; 17 – staircase vestibule; 18 – cochlea aqueduct; 19 – cochlear window; 20 – cape; 21 – bone auditory tube; 22 – lentil-shaped bone; 23 – tensor tympani; 24 – tympanic cavity
The equilibrium auditory organ consists of the outer, middle and inner ear.
Outer ear- This is the sound-receiving section of the organ, consisting of the auricle, its well-developed muscles (there are more than 20 of them) and the long external auditory canal. The auricle is movable skin fold funnel-shaped with pointed or rounded ends, not large size, very mobile, and also covered with hair. Its base is formed by elastic cartilage.
The external auditory canal serves to conduct sound vibrations to the eardrum.
Middle ear- a sound-conducting and sound-transforming organ of the vestibulocochlear organ, represented by the tympanic cavity with a chain of auditory ossicles in it. Tympanic cavity located in the tympanic part of the petrous bone. On the back wall of this cavity there are 2 openings, or windows: the window of the vestibule, closed by the stapes, and the window of the cochlea, closed by the internal membrane. On the front wall there is a hole leading into the auditory (Eustachian) tube, which opens into the pharynx. The eardrum is a weakly extensible membrane about 0.1 mm thick that separates the middle ear from the outer ear. The auditory ossicles of the middle ear are represented by the so-called hammer, incus, lentiform bone and stapes. With the help of ligaments and joints, they are united into a chain, which at one end rests against the eardrum and at the other against the window of the vestibule. Through this chain of auditory ossicles, sound vibrations are transmitted from the eardrum to the fluid of the inner ear - perilymph.
Inner ear- a section of the vestibulocochlear organ of a spiral shape, in which the receptors for balance and hearing are located. It is a system of cavities in the petrous part of the temporal bone: a bony labyrinth with a membranous labyrinth located inside it. Between these labyrinths there is a space filled with perilymph.
The bony labyrinth consists of the vestibule, 3 semicircular canals and the cochlea. The membranous labyrinth is a collection of small cavities communicating with each other, the walls of which are formed by connective tissue membranes, and the cavities themselves are filled with fluid (endolymph). It includes the semicircular canals, the oval and round sac, and the membranous cochlea. On the cavity side, the membrane is covered with epithelium, forming the receptor part auditory analyzer– spiral (corti) organ. It consists of auditory (hair) and supporting (support) cells. Nervous excitation arising in the auditory cells is conducted to the cortical centers of the auditory analyzer. At waves of a certain length, auditory receptors are excited, in which the physical energy of sound vibrations is converted into nerve impulses.
In the oval and round sacs there are statoliths, which, with the so-called equilibrium ridges and sensitive (equilibrium) spots, or macules, constitute the vestibular apparatus, which perceives the movement of the head and changes in its position associated with a sense of balance. The receptors of the small oval sac are excited when the vertical position of the head changes, and the large round sac is excited when the horizontal position changes. Signs of pathology of the balance organ are changes in the animal’s gait: unsteadiness, lack of coordination of movement, pendulum-like movements, etc.
Pig has very acute hearing. It distinguishes sounds that are not audible to humans. This animal not only picks up the frequency of sound, but also distinguishes individual commands and melodies, differentiates them and recognizes them.
Endocrine glands
Endocrine glands include organs, tissues, groups of cells that release hormones into the blood through the walls of capillaries - highly active biological regulators of metabolism, functions and development of the animal’s body. There are no excretory ducts in the endocrine glands.
The following endocrine glands exist in the form of organs: pituitary gland, pineal gland (epiphysis), thyroid gland, parathyroid glands, pancreas, adrenal glands, gonads (in males - testes, in females - ovary).
Pituitary lies at the base sphenoid bone. It produces a number of hormones: thyroid-stimulating – stimulates the development and functioning of the thyroid gland; adrenocorticotropic – enhances the growth of adrenal cortex cells and the secretion of hormones in them; follicle-stimulating – stimulates the maturation of follicles in the ovary and the secretion of female genital organs, spermatogenesis (sperm formation) in males; somatotropic – stimulates tissue growth processes; prolactin – takes part in lactation; oxytocin - causes contraction of the smooth muscles of the uterus; Vasopressin – stimulates the absorption of water in the kidneys and increases blood pressure. Impaired functioning of the pituitary gland causes gigantism (acromegaly) or dwarfism (nanism), sexual dysfunction, exhaustion, hair and teeth loss.
The pineal gland, or pineal gland, is located in the diencephalon region. Hormones (melatonin, serotonin and antigonadotropin) are involved in the regulation of sexual activity in animals, biological rhythms and sleep, reactions to exposure to light.
Thyroid gland The isthmus is divided into right and left lobes, located behind the trachea in the neck. The hormones thyroxine and triiodothyronine regulate oxidative processes in the body, affect all types of metabolism and enzymatic processes. They contain iodine. Thyroid calcitonin, counteracting parathyroid hormone, reduces calcium levels in the blood. The thyroid gland also influences tissue growth, development, and differentiation.
Parathyroid glands located near the wall of the thyroid gland. The parathyroid hormone they secrete regulates the calcium content in the bones, enhances the absorption of calcium in the intestines, and the release of phosphates in the kidneys.
Pancreas produces insulin, a hormone that regulates blood sugar levels. An increase in blood sugar levels leads to an increase in its content in the urine, as the body tries to reduce the amount of sugar.
Adrenal glands- a paired organ lying in the fatty capsule of the kidneys. They synthesize the hormones aldosterone, corticosterone (hydrocortisone) and cortisone, which is the opposite of insulin.
Sex glands males are represented by testes that produce male reproductive cells and testosterone, an internal secretion hormone. This hormone stimulates the development and manifestation of sexual reflexes, takes part in the regulation of spermatogenesis, and influences sex differentiation.
In females, the gonads are paired ovaries, where reproductive eggs are formed and mature, and sex hormones – estradiol and metabolites – are produced. Estradiol and its metabolites estrone and estriol stimulate the growth and development of female genital organs, participate in the regulation of the sexual cycle, and affect metabolism. Progesterone is a hormone of the corpus luteum of the ovaries, which ensures the normal development of a fertilized egg. In the body of females, under the influence of testosterone, which is produced in small quantities in the ovaries, follicles are formed and the sexual cycle is regulated.
Hormones produced by the endocrine glands have the property of influencing metabolism and a number of important life processes in the body of animals. When the secretory function of this group of glands is disrupted (decreased or increased), specific diseases arise in the body - metabolic disorders, deviation from normal growth, sexual development and other deviations.
Digestive system
The digestive system carries out the exchange of substances between the body and the environment. Through the digestive organs, the body receives with food all the substances it needs - proteins, fats, carbohydrates, mineral salts, vitamins - and undigested food remains and part of the metabolic products are released into the external environment.
The digestive tract is a hollow tube consisting of mucous membrane and muscle fibers. It begins in the mouth and ends in the anus. Along its entire length digestive tract has specialized sections that are designed to move and absorb ingested food.
The digestive tract consists of several sections: the oral cavity, pharynx, esophagus, stomach, small and large intestines, rectum and anus (Fig. 12). Pigs need to drink 15-25 liters of water per day. Normally, 0.5-3 kg of feces are released per day, soft consistency, brownish color. The percentage of water content in normal feces is 55-75%. Any deviations from the norm indicate the possible occurrence of a disease.
Rice. 12. Diagram of the pig’s digestive organs:1 – esophagus; 2 – stomach; 3 – duodenum; 4 – ileum; 5 – jejunum; 6 – cecum; 7 – transverse colon; 8 – small colon; 9 – rectum
Oral cavity includes top and lower lips, cheeks, tongue, teeth, gums, hard and soft palate, salivary glands, tonsils, pharynx. With the exception of the crowns of the teeth, its entire internal surface is covered with mucous membrane, which can be pigmented.
The upper lip merges with the nose, forming a snout - a snout. It developed in connection with the way of life of wild ancestors - digging the earth. Normally it is moist and cool, but at elevated temperatures it becomes dry and warm.
The lips and cheeks are designed to hold food in the mouth and serve as the vestibule of the oral cavity.
The tongue is a muscular movable organ located at the bottom of the oral cavity that performs several functions: tasting food, participating in the process of swallowing and drinking, as well as in feeling objects, stripping soft tissues from bones, caring for the body, hair, and also serves for contact with other individuals. On the surface of the tongue there is a large number of horny papillae: mechanical (grasping and licking food) and gustatory (taste organ) (Fig. 13).
Rice. 13. Pig Tongue:
1 – root; 2 – body; 3 – apex; 4 – filiform papillae; 5 – fungiform papillae; 6 – valicular papillae; 7 – leaf-shaped papillae; 8 – cone-shaped papillae
Teeth are bony enamel organs for capturing and grinding food. In pigs, these organs have a tuberous surface because they are adapted for crushing and grinding food. The teeth are divided into incisors, canines (hook-shaped), premolars, or premolars, molars, or molars (Fig. 14).
Rice. 14. Roof of the pig's mouth:
1 – fangs; 2 – incisive papilla; 3 – incisor teeth; 4 – palatal ridges; 5 – premolars; 6 – molars; 7 – palatal suture; 8 – molars
Piglets are born with marginal incisors, and in the 1st-2nd week after birth the remaining milk teeth erupt. The so-called baby jaw consists of 28 teeth. It lacks molars. Replacing baby teeth with molars begins at 8 months and lasts up to 18 months. It should be noted that premolars, appearing at 3.5-6.5 months, are not replaced by permanent teeth. Molars appear at 4-6 months. The jaw of an adult animal consists of 44 teeth (Table 3). The canines are usually very strongly developed, especially in males, and are transformed into protruding tusks; they are mostly triangular in shape. The canines of the upper jaw are curved upward and, when applied to the lower ones, sometimes form together as if one tusk.
Table 3Pig dental formula
Gums are folds of mucous membrane that cover the jaws and strengthen the position of the teeth in the bone cells. The hard palate is the roof of the oral cavity and separates it from the nasal cavity, and the soft palate, a continuation of the mucous membrane of the hard palate, is located freely on the border of the oral cavity and pharynx, separating them. The gums, tongue and roof of the mouth may be unevenly pigmented pink. Color changes are a sign of disease.
Several paired salivary glands open directly into the oral cavity, the names of which correspond to their location: parotid, submandibular, sublingual, molar and supraorbital (zygomatic). The secretion of the glands contains enzymes that break down starch and maltose.
Tonsils are organs of the lymphatic system and perform a protective function in the body.
Digestion in pigs begins in the oral cavity, where food remains for a short time. Here, food is subjected to mechanical grinding and initial processing under the action of salivary enzymes, which also ensures the formation of a food coma.
Depending on the type of feeding, pigs normally produce 500-800 ml of saliva per day. The formed food lump, with the help of movements of the tongue and cheeks, reaches the root of the tongue, which lifts it to hard palate and moves towards the throat. The entrance to the pharynx is called the pharynx.
Throat - a funnel-shaped cavity lined with mucous membrane and having powerful muscles. It connects the oral cavity to the esophagus, and the nasal cavity to the lungs. The oropharynx, nasopharynx, two eustachian or auditory tubes, trachea and esophagus open into the pharynx.
Esophagus It is a muscular tube through which food is transported in a circular manner from the pharynx to the stomach. It is formed almost entirely by skeletal muscles.
Stomach- a direct continuation of the esophagus, which is a sac-shaped cavity organ (Fig. 15). Pigs have a single-chamber stomach of the esophageal-intestinal type. This organ is located in the left hypochondrium and is adjacent to the diaphragm and liver.
Rice. 15. Single-chamber pig stomach:
1 – diverticulum; 2 – entrance to the diverticulum; 3 – cardiac part; 4 – bottom part; 5 – pyloric part; 6 – esophagus; 7 – duodenum; 8 – pyloric eminence
From the esophagus, the mushy food enters the stomach, where it is arranged in layers and does not mix with gastric juice for a long time. Therefore, in the first hours after eating, an alkaline environment remains inside the stomach contents, which promotes the breakdown of carbohydrates into glucose, as well as the fermentation process caused by microorganisms in the feed. Then the feed masses are soaked in acidic gastric juice. After 4-6 hours from the start of a meal, half of the food remains in the stomach, and the other, due to wave-like contractions of the stomach muscles, moves towards the intestines.
Intestines pig is a hollow tube arranged in the form of numerous twisted loops. This segment of the digestive system is divided, in turn, into a thin and thick section. The entire intestine is 10 times longer than the body.
Small intestine starts from the stomach and is divided into three main parts:
› duodenum (first and shortest part small intestine 40-90 cm long, into which the bile ducts and pancreatic ducts exit);
› jejunum (the longest part of the intestine, up to 14 m long, suspended in the form of many loops on the extensive mesentery);
› ileum (a continuation of the jejunum about 4 m long).
The small intestine is localized in the right hypochondrium and goes to the level of the IV lumbar vertebra. The mucous membrane of the small intestine is more specialized for the digestion and absorption of food: it is assembled into folds called villi, which increase the absorptive surface of the intestine.
The pancreas also lies in the right hypochondrium and secretes several liters of pancreatic secretion into the duodenum per day, containing enzymes that break down proteins, carbohydrates and fats, as well as the hormone insulin, which regulates blood sugar levels.
The pig's liver is light red in color, relatively large in size, located mostly in the right hypochondrium up to the 13th intercostal space, and a smaller part in the left hypochondrium up to the 10th rib. Its mass is about 2.5% of the animal’s body weight.
The liver passes and filters blood flowing through the portal vein from the stomach, spleen and intestines; complex processes of metabolism of nitrogenous compounds, carbohydrates, fats are carried out; Toxic metabolic products are neutralized. The liver produces bile, which converts fats before they can be absorbed into the blood vessels intestinal wall. Bile accumulates in the gallbladder, and from there through the bile duct enters the duodenum. During the embryonic period, the main processes of hematopoiesis occur in the liver. Its removal leads to the death of the animal.
In the small intestine, the contents of the stomach are exposed to bile, intestinal and pancreatic juices, which promotes the breakdown of nutrients into simple components and their absorption into the blood and lymph. This process occurs in pigs in 2.5 hours.
Large intestine represented by the cecum, colon and rectum, ending in the anal canal with the anus. The contents from the small intestine enter the large intestine, where it remains for about 30-36 hours. There are no villi on the mucous membrane of the large intestine, but there are depressions - crypts, where the intestinal glands are located, secreting a small amount of juices containing a lot of mucus, but few enzymes. Microbes in the intestinal contents cause the fermentation of carbohydrates, and putrefactive bacteria cause the destruction of residual products of protein digestion, and harmful compounds such as indole, skatole, phenols are formed, which, when absorbed into the blood, can cause intoxication, which occurs, for example, with protein overfeeding, dysbacteriosis , lack of carbohydrates in the diet. These substances are neutralized in the liver.
Water (up to 95%) and some minerals are intensively absorbed in the large intestines.
Due to strong peristaltic contractions of the muscles of the colon, the remaining contents pass through the colon into the rectum, where the formation and accumulation of feces occurs. The release of the remaining contents begins 11-13 hours after eating (morning feeding) or 13-15 hours during evening feeding. The maximum period of excretion is 24-36 hours. The very last undigested residues are excreted after 4-5 hours.
The release of feces into the environment occurs through the anal canal (anus). Over the course of a year, a pig produces about 1 ton of manure, which can be used as fertilizer.
Respiratory system
The respiratory system ensures the entry of oxygen into the body and the removal of carbon dioxide, i.e. gas exchange between atmospheric air and blood. In terrestrial animals, gas exchange occurs in the lungs, which are located in the chest. Alternate contraction of the muscles of the inhalers and exhalers leads to expansion and contraction of the chest, and with it the lungs. This ensures that air is drawn in through the air passages into the lungs (inhalation) and expelled back out (exhalation). Contractions of the respiratory muscles are controlled by the nervous system.
While passing through the airways, the inhaled air is moistened, warmed, cleared of dust, and also examined for odors using the olfactory organ. With exhaled air, some water (in the form of steam), excess heat, and some gases are removed from the body. Sounds are produced in the air passages (larynx).
The respiratory organs are represented by the nose and nasal cavity, larynx, trachea and lungs.
Nose Together with the mouth, it makes up the anterior part of the head in animals - the muzzle. On the nose there are apex, back, side parts and root, which are devoid of hair and contain numerous glands, receptors, and short sensitive hairs. In a pig, due to the lifestyle of its wild ancestors, the tip of the nose with the upper lip forms a proboscis (piglet), which has the shape of a disk. Thanks to the secretion of these hairs, the surface of the snout in healthy animals is always wet and cold to the touch, while in animals with elevated body temperature it is dry and hot.
The nose contains a paired nasal cavity, which is the initial section of the airways. IN nasal cavity The inhaled air is examined for odors, heated, humidified, and cleaned of contaminants. The nasal cavity communicates with the external environment through the nostrils, with the pharynx through the choanae, with the conjunctival sac through the nasolacrimal canal, and also with the paranasal sinuses.
The paranasal sinuses communicate with the nasal cavity. The paranasal sinuses are air-filled and mucous-lined cavities between the outer and inner plates of some flat bones of the skull (for example, frontal bone). Because of this message, inflammatory processes from the mucous membrane of the nasal cavity can easily spread to the sinuses, which complicates the course of the disease.
Larynx- a section of the respiratory tube located between the pharynx and trachea and suspended on the hyoid bone. The peculiar structure of the larynx allows it to perform, in addition to conducting air, other functions. It isolates the respiratory tract when swallowing food, serves as a support for the trachea, pharynx and the beginning of the esophagus, and serves as a vocal organ. The skeleton of the larynx is formed by five movably interconnected cartilages, on which the muscles of the larynx and pharynx are attached, and the laryngeal cavity is lined with mucous membrane. Between the two cartilages of the larynx passes transverse fold- the so-called vocal lip, which divides the laryngeal cavity into two parts. It contains the vocal cord and vocal muscle. The tension of the vocal lips during exhalation creates and regulates sounds.
Trachea serves to conduct air into the lungs and back. This is a tube with a constantly gaping lumen, which is ensured by rings of hyaline cartilage that are not closed at the top in its wall. The inside of the trachea is lined with mucous membrane. It extends from the larynx to the base of the heart, where it divides into two bronchi, which form the basis of the roots of the lungs. This location is called the tracheal bifurcation.
Lungs- the main respiratory organs, directly in which gas exchange occurs between the inhaled air and blood through the thin wall separating them. To ensure gas exchange, a large contact area is required between the airways and bloodstreams. Therefore, the airways of the lungs - the bronchi - like a tree, branch repeatedly to the bronchioles (small bronchi) and end with numerous small pulmonary vesicles - alveoli, which form the lung parenchyma (parenchyma is a specific part of the organ that performs its main function). Blood vessels branch parallel to the bronchi and entwine the alveoli with a dense capillary network, where gas exchange takes place. Thus, the main components of the lungs are the airways and blood vessels. Connective tissue unites them into a paired compact organ - the right and left lungs. The lungs are located in the chest cavity, adjacent to its walls. The right lung is slightly larger than the left, because the heart, located between the lungs, is shifted to the left. In a pig, the relative lung weight is about 0.42%.
Normally, the number of inhalations and exhalations (the frequency of respiratory movements of the chest per minute) in a healthy pig fluctuates within significant limits. This breadth of the range depends on a number of factors, for example, on the body’s metabolism, ambient temperature, muscle load, and physiological state (Table 4).
Table 4Respiratory rate of a pig at restNewborn piglets – 70-108
Piglets aged 1 month – 30-45
Piglets aged 4 months – 20-36
Adult pigs – 8-12
Urinary system
The urinary system is designed to remove end products of metabolism in the form of urine from the body (from the blood) into the external environment and to maintain the water-salt balance of the body. In addition, the kidneys produce hormones that regulate hematopoiesis (hemopoietin) and blood pressure(renin). Therefore, dysfunction of the urinary organs leads to severe illness and often death of animals.
The urinary organs include paired kidneys and ureters, unpaired bladder and urethra. The kidneys constantly produce urine, which is discharged through the ureter into the bladder and, as it fills, is released out through the urethra. In males, this canal also carries reproductive products and is therefore called the urogenital canal. In females, the urethra opens into the vestibule of the vagina.
Kidneys– paired long bean-shaped organs of dense consistency, red-brown color, smooth, covered on the outside with three membranes: fibrous, fatty, serous. The right and left kidneys lie under the I-III lumbar vertebrae, and the right kidney does not come into contact with the liver (Fig. 16). The structure of pig kidneys is very similar to the structure of human kidneys.
Rice. 16. Topography of pig kidneys from the ventral surface:
1 – 14th rib; 2 – right kidney; 3 – lumbar vertebrae; 4 – left kidney
Near the middle of the inner layer, vessels and nerves enter the organ and the ureter emerges. This place is called the renal hilum. On the section of each kidney, the cortical (or urinary), medullary (or urinary) and intermediate zones, where the arteries are located, are distinguished. In the cortical layer there are renal corpuscles, consisting of a glomerulus (vascular glomerulus), which is formed by the capillaries of the afferent artery, and a capsule, and in the medulla there are convoluted tubules. The renal corpuscle, together with the convoluted tubule and its vessels, makes up the structural and functional unit of the kidney - the nephron. In the renal corpuscle of the nephron, liquid - primary urine - is filtered from the blood of the vascular glomerulus into the cavity of its capsule. During the passage of primary urine through the convoluted tubule of the nephron, most (up to 99%) water and some substances that cannot be removed from the body, such as sugar, are absorbed back into the blood. This explains the large number of nephrons and their length. Urine then passes from the tubules into the ureter.
Ureter- a tube-shaped paired organ designed to conduct urine into the bladder. It travels to the pelvic cavity, where it drains into the bladder. The ureter makes a small loop in the wall of the bladder, which prevents urine from flowing back from the bladder into the ureters without interfering with the flow of urine from the kidneys to the bladder.
Bladder– a reservoir for urine continuously flowing from the kidneys, which is periodically excreted through the urethra (Fig. 17). It is a pear-shaped membranous muscle sac, which has a special sphincter that prevents the arbitrary release of urine. The empty bladder lies at the bottom of the pelvic cavity, and when full, partially hangs into the abdominal cavity.
Rice. 17. Bladder and urethra of a boar:
1 – top; 2 – body; 3 – neck of the bladder; 4 – opening of the ureter; 5 – urethral ridge; 6 – seminal mound; 7 – urethra
Urethra, or urethra, serves to remove urine from the bladder and is a tube made of mucous and muscular membranes. In males, the urethra is long, thin with numerous stenoses (narrowings), while in females it is relatively short and wide. The internal end of the urethra begins from the neck of the bladder, and the external opening opens in males on the head of the penis, and in females - on the border between the vagina and its vestibule. The auricular part of the long urethra of males is part of the penis, and therefore, in addition to urine, it removes sexual products.
Depending on the type of feeding, an adult pig excretes 2-4 liters (maximum 6 liters) of slightly acidic urine (pH 5.0-7.0) per day. Urine is a clear, straw-yellow liquid. If it is colored intense yellow or brown, then this indicates some kind of health problem.
Reproductive organ system
The reproductive organ system is closely connected with all body systems, in particular with the excretory organs. Its main function is to continue the look.
Male genitals
The boar's genitals are represented by paired organs: testes (testes) with appendages, vas deferens and spermatic cords, accessory sex glands; and unpaired organs: the scrotum, urogenital canal, penis and prepuce (Fig. 18).
Rice. 18. Genitourinary apparatus of a boar:
1 – kidneys; 2 – ureters; 3 – bladder; 4 – testes; 5 – epididymis; 6 – scrotum; 7 – prepuce; 8 – seed tube; 9 – vesicular glands; 10 – rectum; 11 – penis; 12 – bulbous, or Cooper, glands; 13 – head, or end part
Males produce about 250-500 ml of gray-white sperm in the form of watery flakes, 1 mm 3 of which contains 50-250 thousand sperm.
Testis- the main reproductive paired organ of males, in which the development and maturation of sperm occurs, is also an endocrine gland - produces male sex hormones. In boars this organ is very large.
The testis is ovoid in shape, suspended on the spermatic cord and located in the cavity of the sac-like protrusion of the abdominal wall - the scrotum. Closely associated with it is its appendage, which is part of the excretory duct. In the epididymis, mature sperm can remain motionless for quite a long time, are provided with nutrition during this period, and when animals mate, they are released into the vas deferens by peristaltic contractions of the muscles of the epididymis.
Scrotum- the receptacle of the testis and its appendage, which is a protrusion of the abdominal wall. In boars it is located closer to the anus.
The temperature in the scrotum is lower than in the abdominal cavity, which favors the development of sperm. The skin of this organ is covered with small hair and has sweat and sebaceous glands. The muscular-elastic membrane is located under the skin and forms the septum of the scrotum, as a result of which the organ cavity is divided into two parts. The muscular formations of the scrotum ensure that the testis is pulled towards the inguinal canal at low external temperatures.
Vas deferens, or vas deferens, is a continuation of the epididymal duct in the form of a narrow tube of three membranes. It starts from the tail of the appendage, consisting of spermatic cord through the inguinal canal it is directed into the abdominal cavity, and then into the pelvic cavity, where it forms an ampoule. Behind the neck of the bladder, the vas deferens connects with the excretory duct of the vesicular gland into a short ejaculatory canal, which opens at the beginning of the genitourinary canal.
Spermatic cord- This is a fold of the peritoneum that contains vessels, nerves going to the testis, and lymphatic vessels leaving the testis, as well as the vas deferens.
Urogenital canal, or male urethra, serves to remove urine and sperm. It begins with the urethral opening from the neck of the bladder and ends with the external urethral opening on the head of the penis. The initial, very short part of the urethra - from the cervix to the confluence of the ejaculatory duct - conducts only urine. The wall of the male urethra is formed by a mucous membrane, a spongy layer and a muscular layer.
In addition to the glands present in the ampoules of the vas deferens, to accessory sex glands include paired vesicles, prostate gland, paired bulbous glands located on the upper wall of the bladder neck. The ducts of these glands open into the urethra.
The vesicular glands produce a sticky secretion that dilutes the mass of sperm. In boars, these glands are quite large - up to 15 cm long. The secretion of the prostate gland activates sperm motility. This gland is small, 2.5 cm in size. The secretion of the bulbous glands helps clear the urogenital canal from urine residues and lubricate the urethral mucosa before the passage of sperm. In a boar, the gland reaches 12 cm in length and 3 cm in width.
Penis, or penis, performs the function of introducing male sperm into the female genitals, as well as removing urine from the body. The penis consists of the cavernous body of the penis and the penile (udal) part of the urogenital canal.
The penis is divided into root, body and head. The root and body below are covered with skin, the latter extends to the head, forming a fold at the transition to it - the prepuce, or foreskin.
Prepuce- This is a skin fold. When the penis is not erect, the prepuce completely covers the head of the penis, protecting it from damage.
Female genitals
The reproductive organs of female pigs include paired organs: ovaries, fallopian tubes; and unpaired: uterus, vagina, vestibule and external genitalia (Fig. 19).
Rice. 19. Pig genitourinary organs:
1 – ovary; 2 – wide uterine ligament; 3 – oviduct; 4 – uterine horns; 5 – body of the uterus; 6 – cervix; 7 – openings of the vestibular glands; 8 – vagina; 9 – hymen; 10 – opening of the urogenital canal; 11 – vestibule of the vagina; 12 – labia; 13 – clitoris
Ovary- a bean-shaped organ located in a pig behind the kidneys at the level of the VI-VII lumbar vertebrae. In the ovary, female reproductive cells - eggs - develop, and female sex hormones are also formed. Most of the ovary is covered with rudimentary epithelium, under which there is a follicular zone, where the development of follicles with eggs enclosed in them occurs. The wall of a mature follicle bursts and the follicular fluid flows out along with the egg. This moment is called ovulation. In place of the burst follicle, a corpus luteum is formed, which secretes a hormone that inhibits the development of new follicles. In the absence of pregnancy, as well as after childbirth, the corpus luteum resolves.
fallopian tube, or oviduct, is a narrow, highly convoluted tube connected to the uterine horn 15-30 cm long. It serves as the site of fertilization of the egg, conducts the fertilized egg into the uterus, which is carried out both through contraction of the muscular lining of the fallopian tube and through the movement of the ciliated cilia epithelium lining the oviduct.
Uterus is a hollow membranous organ in which the fetus develops. During childbirth, the latter is pushed out by the uterus through the birth canal.
The uterus is divided into horns, body and cervix. The horns on top start from the fallopian tubes, and below they grow together into the body. Due to the multiple pregnancy of the pig, they are convoluted like intestinal loops, and their length is 140 cm. The body of the uterus is small - 5 cm. The uterine cavity passes into a narrow cervical canal (15-18 cm long), which opens into the vagina. The uterus lies entirely in the abdominal cavity.
Sperm live in the uterus of pigs for 12-18 hours.
Vagina – a tubular organ that serves as an organ of copulation and is located between the cervix and the urogenital opening. A pig's vagina is narrow, up to 10-12 cm long.
Vaginal vestibule- the common area of the urinary and genital tract, the continuation of the vagina behind the external opening of the urethra. It ends with the external genitalia.
External genitalia of females represented by the female private area - the vulva, the private lips located between the private slit, and the clitoris.
The vulva is located below the anus and is separated from it by a short perineum. The opening of the urethra opens on the lower wall of the vestibule of the vulva.
The pudendal lips surround the entrance to the vestibule of the vagina. These are folds of skin that pass into the mucous membrane of the vestibule.
The clitoris is an analogue of the male penis, built from cavernous bodies, but less developed.
In a pig, a tongue-like outgrowth hangs from the ventral (lower) commissure of the labia, which provides better fixation of the penis during sexual intercourse.
Pig breeding
Reproduction (reproduction) is the ability of all living organisms to reproduce their own kind (offspring), ensuring the continuity of life of the species and the continuity of generations upon the fusion of two sex cells - a sperm and an egg. The formation of germ cells is possible at the onset of puberty. In pigs, puberty usually occurs at 5-8 months: this age depends on the breed and physical condition of the animal, but such young individuals, as a rule, are not allowed to mate, since its onset does not indicate the readiness of the body to reproduce offspring. At 10-15 months, pigs are considered physiologically mature and ready for reproduction. Young pigs can be mated at 8-9 months, if they have reached a weight of 130-150 kg, and boars - at least one year old, when their weight is 180-200 kg.
Pigs are called polyestrous animals because they have several estrous (sexual) cycles throughout the year. The reproductive cycle is the totality of all physiological changes occurring in the female reproductive system from one ovulation to the next. Each of them lasts 18-21 days. During the cycle, a number of sequential changes in the cellular and hormonal level– such as preparation for egg fertilization and pregnancy. This is the stage of excitement - females worry, run, squeal, refuse food (1-2 days); estrus – there is swelling of the vulva, redness of the vaginal mucosa and mucus discharge from it (2-3 days); sexual heat - desire for a boar: the pig becomes restless, shrill, refuses to feed, often becomes urinating, raises its tail, the so-called immobility reflex appears, etc. (1-2 days). Ovulation, i.e. the release of an egg ready for fertilization from the ovary, usually occurs approximately on the 2nd day after the onset of heat, ending within 24-48 hours. After ovulation, the stage of inhibition and balancing immediately begins: females calm down, appetite is restored. The period of relative rest takes 14-16 days. If pregnancy does not occur after insemination or mating, the equilibration stage lasts until a new arousal stage. After childbirth, the sexual cycle most often resumes on the 55-60th day, which depends mainly on their breed, living conditions, feeding, care and use. After 6-8 years, pigs stop estrus.
In the event of fertilization, nutrients accumulate in the female’s body. Pregnancy (pregnancy) in domestic pigs lasts about 4 months (110-118 days) and ends with childbirth.
Childbirth, or farrowing, is a physiological process in which a mature fetus, its membranes (afterbirth) and the fetal fluid contained in them are expelled from the uterine cavity. Childbirth is accompanied by contractions of the uterine muscles (contractions) and abdominal muscles (pushing). The cervical canal opens due to the introduction of fetal membranes into it in the form of amniotic fluid. As it passes through the vagina, the germinal vesicle often bursts and anterior or hind limbs fetus With the correct position of the fetus (when the front limbs come first, on which the head lies on top, or the hind limbs, on which the tail lies on top), labor proceeds quickly. If the fetus is not positioned correctly, childbirth usually cannot take place without assistance. Then the afterbirth (placenta) is released. In pigs, the preparatory period of birth lasts 2-6 hours (rarely longer), the period of fetal excretion - the first fetus appears after 2-6 hours, the rest - after 2-20 minutes, the period of expulsion of the placenta - along with the fetus or soon after birth (up to 3 h). Pigs give birth to 8-16 piglets weighing 0.8-1.5 kg.
The processes of involution (reverse development) of the uterus are accompanied by the release of lochia from its cavity, consisting of the remainder of the amniotic fluid, particles of the placenta, afterbirth, blood, fibrin, etc. In pigs they are released in small quantities for 3-5 days. Complete involution of the uterus ends 8-10 days after birth.
After farrowing, lactation begins in the female’s body (the process of formation and secretion of milk from the mammary glands), lasting up to 2 months or more, provided the suckling is fed with milk. The mammary glands (udder) develop at the end of pregnancy, and after childbirth reach highest development. The secretion of colostrum begins a few days before childbirth and sharply increases after it. During birth, it is necessary to wash the pig's mammary gland with a warm solution, squeeze out the first streams of colostrum and allow the newborns to suck. Newborns need to drink colostrum to gain so-called colostrum immunity, which protects the body from pathogens. From the 2-3rd day after birth, the composition of colostrum changes, and by the 5-8th day it becomes milk. There are times when not enough milk is produced, especially in first-bred mothers. In this case, the piglets should be placed with another sow, and the patient should be given dairy feed (whey, skim milk, beets, carrots, etc.) into the patient’s diet and, if necessary, undergo a course of therapeutic procedures.
The mother feeds the piglets with milk alone until they are a week old. Typically, a piglet drinks approximately 60-80 ml of milk per suckling. I note that the anterior nipples of the uterus (mammary) produce more colostrum and milk than the posterior (inguinal) nipples, so piglets that weigh less and are less developed are brought to the anterior nipples. Then fertilizers are gradually introduced: roasted barley or peas, cow's milk, grass, hydroponic greens. At 2-3 weeks of age, piglets can eat a large amount of additional feed, in the summer, for example, green grass from pastures, and in winter - turf, which serves as an excellent preventive measure. nutritional anemia. Weaning can begin at 4-5 weeks of age, when the piglets eat any feed from the feeder (dry or wet).
During weaning, antibiotics can be added to the feed to prevent digestive disorders.
To improve the quality of meat, speed up fattening and reduce the aggressiveness of males, they are castrated. Castration is the surgical removal of the gonads.
It is best to castrate boars at the age of 1-2 months in the warm season.
If problems arise with the reproductive organs, sterilization is carried out. During sterilization, the genitals of animals remain, but their functions are disrupted through surgery.
Cardiovascular system
The cardiovascular system in the animal’s body ensures metabolism through constant circulation of blood and lymph vessels, which play the role of liquid transport. This process is called blood-lymph circulation. With the help of blood circulation, there is an uninterrupted supply of cells and tissues of the body with oxygen, nutrients, water absorbed into the blood or lymph through the walls of the respiratory and digestive apparatus, and the release of carbon dioxide and other metabolic end products harmful to the body. Hormones, antibodies and other physiologically active substances are transported in the blood, resulting in the activity of the immune system and hormonal regulation processes occurring in the body with the leading role of the nervous system. Blood circulation, the most important factor in the body’s adaptation to changing conditions of the external and internal environment, plays a leading role in maintaining its homeostasis (constancy of the composition and properties of the body). Poor circulation leads primarily to metabolic disorders and functional functions of organs throughout the body.
The cardiovascular system is represented by a closed network of vessels with a central organ – the heart. Based on the nature of the circulating fluid, it is divided into circulatory and lymphatic.
Circulatory system
The circulatory system includes: the heart - the central organ that promotes the movement of blood through the vessels, and blood vessels - arteries that carry blood from the heart to the organs, veins that return blood to the heart and blood capillaries, through the walls of which the exchange of substances between blood and tissues occurs in the organ. Vessels of all 3 types communicate with each other along the way through anastomoses that exist between vessels of the same type and between various types vessels. There are arterial, venous or arteriovenous anastomoses. Due to them, networks are formed (especially between capillaries), collectors, collaterals - lateral vessels accompanying the course of the main vessel.
Heart- the central organ of the cardiovascular system, propelling blood through the vessels, like a motor. This is a powerful hollow muscular organ located obliquely vertically in the mediastinum of the thoracic cavity, in the area from the 3rd to 6th ribs, in front of the diaphragm, in its own serous cavity.
The heart of mammals is four-chambered, completely divided from the inside by the interatrial and interventricular septa into two halves - right and left, each of which consists of 2 chambers - the atrium and the ventricle. According to the nature of the circulating blood, the right half of the heart is venous, and the left half is arterial. The atria and ventricles communicate with each other through the atrioventricular orifices. The embryo (fetus) has an opening through which the atria communicate, and there is also an arterial (botal) duct, through which blood from the pulmonary trunk and the aorta mixes. By the time of birth, these holes are closed. If this does not happen in a timely manner, the blood mixes, which leads to serious disruptions in the functioning of the cardiovascular system.
The main function of the heart is to ensure continuous blood flow in the vessels of both circulation circles. In this case, blood in the heart moves in only one direction - from the atria to the ventricles, and from them to the large arterial vessels. This is ensured by special valves and rhythmic contractions of the heart muscles - first the atria, and then the ventricles, then there is a pause and everything repeats all over again.
The heart wall consists of 3 membranes (layers): endocardium, myocardium and epicardium. Endocardium is the inner lining of the heart, myocardium is the heart muscle (it differs from skeletal muscle tissue by the presence of insertion bars between the individual fibers), epicardium is the outer serosa hearts. The heart is enclosed in a pericardial sac (pericardium), which isolates it from the pleural cavities, fixes the organ in a certain position and creates optimal conditions for functioning. The walls of the left ventricle are 2-3 times thicker than the right.
The heart rate largely depends on the condition of the animal, as well as on its age, physiological state and ambient temperature. Under the influence of heart contractions (due to blood flow), sequential contraction of blood vessels and their relaxation occur. This process is called blood pulsation, or pulse. The pulse is determined through the femoral artery for 0.5-1 min (Table 5) (four fingers are placed on the inner surface in the area of the femoral canal, and the thumb is placed on the outer surface of the thigh).
Table 5Pulse rate in pigsNewborn piglets – 200-250
Piglets 3-4 months – 110-130
Boars – 60-80
Sows – 90-100
Hogs and old pigs – 55-75
According to its functions and structure blood vessels divided into conducting and feeding vessels. Conducting vessels are arteries (they conduct blood from the heart, the blood in them is scarlet, bright, because it is saturated with oxygen, they are located deeper in the animal’s body, under the veins); veins (supply blood to the heart, the blood in them is dark, because it is saturated with metabolic products, they are located closer to the surface of the body); nourishing, or trophic, capillaries (microscopic vessels located in the tissues of organs). The main function of the vascular bed is twofold - conducting blood (through arteries and veins), as well as ensuring metabolism between blood and tissues (links of the microcircular bed) and redistribution of blood. In the organ, the arteries branch repeatedly into arterioles, precapillaries, which turn into capillaries, then into postcapillaries and venules. Venules, which are the last link of the microcirculatory bed, merge with each other and enlarge to form veins that carry blood out of the organ. Blood circulation occurs through a closed system consisting of a large and small circle.
Blood - it is a liquid tissue that circulates in the circulatory system. This is a type of connective tissue that, together with lymph and tissue fluid, makes up the internal environment of the body. It transports oxygen from the pulmonary alveoli to the tissues (due to the respiratory pigment hemoglobin contained in red blood cells) and carbon dioxide from the tissues to the respiratory organs (this is done by salts dissolved in the plasma), as well as nutrients (glucose, amino acids, fatty acids) , salts, etc.) to tissues, and the final metabolic products (urea, uric acid, ammonia, creatine) - from tissues to excretory organs, and also transports biologically active substances (hormones, mediators, electrolytes, metabolic products - metabolites). Blood does not come into contact with the cells of the body; nutrients pass from it to the cells through the tissue fluid that fills the intercellular space. This liquid tissue is involved in the regulation water-salt metabolism And acid-base balance in the body, maintaining a constant body temperature. Blood also protects the body from the effects of bacteria, viruses, toxins, and foreign proteins. The volume of circulating blood in a pig's body is 7-11% of the total live weight and depends on the age, type and breed of the animal.
Blood consists of 2 important components - shaped elements and plasma. Formed elements account for approximately 30-40%, plasma - 70% of the volume of all blood. The formed elements include erythrocytes, leukocytes and platelets (Table 6).
Table 6Composition of the blood of a healthy pigHematocrit – 35-45%
Red blood cells– 5-8 million/mm 3
Hemoglobin– 10-14 g/100 ml
Leukocytes– 7-20 thousand/mm 3
Lymphocytes – 40%
Blood quantity– 68-74 ml/kg live weight
Erythrocytes, or red blood cells, carry oxygen from the lungs to organs and tissues, and also determine the immunological characteristics of the blood. The combination of red blood cell antigens determines the blood group. Leukocytes, or white blood cells, are divided into granular (eosinophils, basophils and neutrophils) and non-granular (monocytes and lymphocytes). The percentage of individual forms of leukocytes constitutes the leukocyte form of blood. All types of leukocytes participate in the body's defense reactions. Platelets, or blood platelets, take part in the blood clotting process.
Blood plasma is its liquid part, consisting of water (91-92%) and organic and mineral substances dissolved in it. The ratio of the volume of formed elements and blood plasma as a percentage is called the hematocrit number.
Lymphatic system
The lymphatic system is a specialized part of the cardiovascular system. It consists of lymph, lymphatic vessels and lymph nodes and performs 2 main functions: drainage and protective.
Lymph – This is a transparent yellowish liquid that is formed as a result of the release of part of the blood plasma from the bloodstream through the walls of capillaries into the surrounding tissues. From the tissues it enters the lymphatic vessels (lymphatic capillaries, postcapillaries, intraorgan and extraorgan lymphatic vessels, ducts). Together with the lymph flowing from the tissues, metabolic products, remnants of dying cells, and microorganisms are removed. In the lymph nodes, lymphocytes from the blood enter the lymph. It flows, like venous blood, centripetally, towards the heart, pouring into large veins.
Lymph nodes- These are compact, bean-shaped organs consisting of reticular tissue (a type of connective tissue). Numerous lymph nodes, located on the path of lymph flow, are the most important barrier-filtration organs in which microorganisms, foreign particles, and degrading cells are retained and subjected to phagocytosis (digestion). This role is performed by lymphocytes. Due to their protective function, lymph nodes can undergo significant changes. In pigs, the inguinal and retropharyngeal lymph nodes are examined, paying attention to their size, consistency, soreness, mobility, and local body temperature.
The formed elements of blood and lymph are short-lived. They are formed in special hematopoietic organs. These include:
› red bone marrow (red blood cells, granular leukocytes, platelets are formed in it), located in tubular bones;
› spleen (lymphocytes, granular leukocytes are formed in it and dying blood cells, mainly erythrocytes, are destroyed). This is an unpaired organ located in the left hypochondrium;
› lymph nodes (lymphocytes are formed in them);
› thymus, or thymus gland (lymphocytes are formed there). It has a paired cervical part, located on the sides of the trachea to the larynx, and an unpaired thoracic part, located in the chest cavity in front of the heart.
To summarize, it should be noted once again that the animal’s health status is judged comprehensively: attention is paid to body temperature, respiratory rate, pulse, as well as the animal’s appearance and behavior. A healthy animal is mobile, reacts to sounds and the appearance of food given. He has no discharge from the nose, eyes, mouth or anus. The skin is clean, without blemishes, dry. A sick individual has sunken eyes, peeling skin, changes in the composition of urine and feces, lack of appetite, apathy, increased body temperature, adoption of uncharacteristic postures, etc. All this indicates an illness in the animal.
The respiratory apparatus is represented by the respiratory organs (respiratory system) and respiratory motility organs (chest, its muscular and ligamentous apparatus, vessels and nerves). The respiratory organs are the lungs, which are located in the chest from the first to the penultimate rib (in horses up to the sixteenth rib) and are covered on the outside with pleura (Fig.).
Rice. Thoracic cavity of cattle (right section): 1 - diaphragm: 2 - diaphragmatic lobe of the lung; 3 -- apical lobe of the lung; 4 -- middle lobe of the lung; 5 - heart; 6 -- dewlap
Rice. Thoracic cavity of cattle (left section): 1 - esophagus; 2 - trachea; 3 -- vagosympathetic trunk; 4 -- left common carotid artery; 5 -- external thoracic artery; 6 -- axillary artery; 7 -- external jugular vein; 8 -- external thoracic vein; 9- axillary vein; 10 -- internal mammary artery; 11 -- internal mammary vein; 12 -- sternocephalic muscle; 13 -- thymus; 14 -- apical lobe (cranial) of the lung; 15 -- diaphragmatic lobe of the lung; 16 -- diaphragm; 17 -- apical lobe (caudal) of the lung; 18 - heart; 19 -- right apical lobe of the lung
There is asymmetry in the structure of the lungs ( right lung always greater than the left) and significant species features, which is associated with the structural features of the chest and the type of breathing (abdominal in ungulates and thoracic, thoraco-abdominal in carnivores). Each lung has a cranial, middle (except for the horse) and caudal lobes, and in the right lung there is also an accessory lobe. In the lungs, air movement occurs due to diffusion. Air enters them through airways in which forced air movement occurs. The airways include: the nasal cavity, nasopharynx, larynx, trachea and bronchi. All airways have a cartilaginous framework, which ensures their constant gaping (preservation of lumen).
The structure of the testis and epididymis. Stages of spermatogenesis
The reproductive organs of males include the testes, epididymis, vas deferens, scrotum (testicular sac), urogenital canal with accessory sex glands, penis and prepuce. The main reproductive gland of males is the testes with their appendages. They are located outside the abdominal and pelvic cavities and are located in the testicular sac.
The testicular sac is a protrusion of the abdominal wall, in bulls in front of the pubic bones, in stallions and males - under the pubic bones, in boars - behind the pubic bones, not far from the anus. The wall of the testicular sac consists of the scrotum, the muscle - the external levator testis and the vaginal membranes.
Scrotum - consists of skin and a muscular-elastic membrane, which fits tightly to the skin of the scrotum. The membrane forms the septum of the scrotum, dividing the latter into two halves, each of which contains the testis with the appendage, covered with vaginal membranes: general (for the testis and appendage) and special (separate for the testis and appendage). Between these membranes there is a cavity that communicates with the abdominal cavity through the inguinal canal.
The testis is a paired ellipsoidal organ in which spermatogenesis occurs in mature animals and sex hormones are produced. The appendage of the testis is closely related to it. On the testis there are: free and adnexal edges; the capitate end to which the head of the appendage is connected; the caudate end, to which the tail of the appendage belongs; lateral and medial surfaces.
The epididymis is a continuation of the vas deferens. It consists of a head, body and tail.
Histological structure of the testis and its appendage.
The testis consists of stroma and parenchyma. The stroma forms the tunica albuginea on the outside of the testis, and on the inside - trabeculae dividing it into lobules filled with convoluted seminiferous tubules, turning into straight ones. The tubules represent the parenchyma of the testis, which also includes interstitial cells lying between the convoluted tubules. The straight tubules become the efferent tubules, which empty into the epididymal canal. The efferent tubules form the head of the epididymis, the canal is the body and tail of the epididymis, giving rise to the vas deferens.
The spermatic cord is a fold of a special vaginal membrane in which the testicular artery and nerves pass to the testis and epididymis, and veins, lymphatic vessels and the vas deferens extend from the testis. The spermatic cord looks like a cone compressed from the sides.
Vas deferens - in the abdominal cavity from the spermatic cord, it is directed caudally, passes along the dorsal surface of the bladder and flows into the urethra. The vas deferens, flowing into the urethra, form a single tubular organ - the urogenital canal, through which urine and sperm pass.
Urogenital canal - begins from the confluence of the vas deferens into the urethra and ends at the head of the penis; consists of the pelvic and penile parts. The pelvic part lies on the pubic and ischial bones and has accessory glands. Bending over the ischial arch, the urogenital canal passes to the ventral surface of the penis, penetrating into it and accompanying it throughout its entire length. This is the genitourinary part of the urogenital canal. The wall of the urogenital canal consists of mucous, vascular and muscular membranes. The choroid, or corpus cavernosum, contains a large amount of smooth muscle tissue, elastic fibers and choroid plexuses with lacunae (cavities), which fill with blood during erection. The urogenital canal opens on the head of the penis.
Accessory sex glands - vesicular, prostatic and bulbous, of a complex alveolar-tubular structure.
The vesicular gland is a steam gland, located on both sides at the final section of the vas deferens, before it flows into the genitourinary canal. The duct of the vesicular gland flows into the urogenital canal along with the vas deferens. The gland secretes a sticky secretion.
The prostate gland is unpaired and consists of parietal and parietal parts. The wall part lies on the neck of the bladder and the beginning of the genitourinary canal. The parietal part is located in the wall of the genitourinary canal, in its cavernous layer, between the mucous and muscular membranes. Prostate secretion increases sperm motility and neutralizes the acidic environment of the vagina.
The bulbous (Cooper's) gland is a steam gland, lying at the caudal end of the pelvic part of the genitourinary canal. It secretes a secretion that cleanses the urogenital canal of urine residues.
Spermatogenesis is conventionally divided into four periods: reproduction, growth, maturation and formation. During the breeding season, mitotic division occurs of a part of the spermatogonia formed from the rudimentary epithelium. The growth period is characterized by an increase in the mass of the cytoplasm of spermatogonia and their transformation into first-order spermatocytes. During the maturation period, two successive divisions of maturation occur: the first is called meiotic and the second is mitotic.
After the first division, from each spermatocyte of the 1st order, two spermatocytes of the 11th order are formed, after the second division, four spermatids with a haploid set of chromosomes are formed. The reduction of genetic material occurs due to the fact that DNA reduplication does not occur before the second division. Spermatids no longer divide. Entering the fourth period of spermatogenesis - the period of formation, they undergo complex rearrangements of cytoplasmic structures, acquire tails and turn into mature sperm. All developing germ cells, except sperm, are united in the tubule through syncytial connections. Mature sperm are much smaller in size than spermatogonia. During development, they lose most of their cytoplasm, minor cellular components and consist only of a head containing a concentrated nuclear substance, and a tail, which ensures their mobility. Part of the cytoplasm with the Golgi apparatus is concentrated at the apical end of the sperm head, and from it an acrosome is formed in the head cap. This organoid plays important role when the head of the sperm penetrates the egg. The total length of sperm is 50 - 70 microns, the average volume is 16 - 19 microns. For each animal species, the time required for the transformation of spermatogonia into mature sperm (including the time spent in the epididymis) is constant, although the differences between species are significant. The duration of spermiogenesis is, in days: for a bull 54 for a camel 56 for a ram 49 for a rabbit 41 for a boar 34 for a male 56 for a stallion 42 for a rooster 25 Spermatozoa that have completed their formation enter the vas deferens. Inside the testis there are straight tubules, the rete testis and efferent tubules of the testis, lined with single-layer squamous epithelium; outside the testis - the epididymal canal and the vas deferens. The latter opens into a canal coming from the bladder, forming together with it the urogenital canal, which passes inside the penis. The canal is surrounded by cavernous corpora cavernosa, capable of swelling.
During copulation, sperm are released not directly from the testis, but from the caudal part of the epididymis. In the epididymal canal, sperm accumulate in large quantities (20 - 40 billion in a bull). Here they undergo further morphofunctional changes within 8 - 20 days. In the acidic, oxygen-free environment of the epididymal canal, sperm enter a state similar to anabiosis, acquire a compacted lipoprotein membrane and a negative charge, which protects them from the action of acidic products and from agglutination in the female genital tract. In the epididymis, the antigenic properties of the sperm surface also change. The fertilizing ability of sperm is retained in the epididymis for up to 2 - 3 months. Sperm that reach the caudal part of the epididymis has a high fertilizing ability and can be released during ejaculation.
The respiratory apparatus is represented by the respiratory organs (respiratory system) and respiratory motility organs (thorax, its muscular and ligamentous apparatus, vessels and nerves). The respiratory organs are the lungs (pulmones, pneumones), which are located in the chest from the 1st rib to the penultimate (in horses up to the 16th rib) and are covered on the outside with pleura (Fig.).
Rice. Cattle thoracic cavity (right section): 1 - diaphragm: 2 - diaphragmatic lobe of the lung; 3 - apical lobe of the lung; 4 - middle lobe of the lung; 5 - heart; 6 - dewlap
Rice. Cattle thoracic cavity (left section): 1 - esophagus; 2 - trachea; 3 - vagosympathetic trunk; 4 - left common carotid artery; 5 - external thoracic artery; 6 - axillary artery; 7 - external jugular vein; 8 - external thoracic vein; 9- axillary vein; 10 - internal mammary artery; 11 - internal mammary vein; 12 - sternocephalic muscle; 13 - thymus; 14 - apical lobe (cranial) of the lung; 15 - diaphragmatic lobe of the lung; 16 - diaphragm; 17 - apical lobe (caudal) of the lung; 18 - heart; 19 - right apical lobe of the lung
In the structure of the lungs, asymmetry is observed (the right lung is always larger than the left) and significant species-specific characteristics, which are associated with the peculiarities of the structure of the chest and the type of breathing (abdominal in ungulates and thoracic, thoraco-abdominal in carnivores). Each lung has a cranial, middle (except for the horse) and caudal lobes, and in the right lung there is also an accessory lobe. In the lungs, air movement occurs due to diffusion. Air enters them through airways in which forced air movement occurs. The airways include: the nasal cavity, nasopharynx, larynx, trachea and bronchi. All airways have a cartilaginous framework, which ensures their constant gaping (preservation of lumen).
The mucous membrane of the nasal cavity is assembled into folds, at the base of which are the nasal turbinates, and between the folds four nasal passages are formed (dorsal, middle, ventral and common). There are two sections in the nasal cavity: olfactory (posterior) and respiratory (anterior). The nasal cavity communicates with the environment through the nostrils, with the nasopharynx through the choanae, with oral cavity- using the naso-palatine canal. It also communicates with the paranasal sinuses, which are reservoirs for air ionization (Fig.).
Rice. External nose of pets: 1 - nasolabial mirror in cattle, nasal in small cattle (goats and sheep) and dogs, stigma in a pig; 2 - nostril
The larynx (larynx) is an organ not only for conducting air, but also for voice production. The cartilaginous skeleton of the larynx is represented by five permanent cartilages: annular, thyroid, arytenoid (paired) and epiglottis (Fig. 1.10).
Rice. The structure of the larynx of small and large livestock: a - sheep; b - goats; c - cows; 1 - epiglottis; 2- thyroid cartilage; 3 - arytenoid cartilage; 4 - ring-shaped cartilage; 5 - vestibule of the larynx; 6 - vocal fold (right); 7 - left vocal cord; 8 - thyroid-epiglottic ligament
The trachea (windpipe) consists of cartilaginous half-rings and in the chest cavity is divided into two bronchi (tracheal bifurcation), which in the lungs form a bronchial tree, its final branches are the alveolar ducts, on which many alveoli are located. The alveoli and alveolar ducts make up the respiratory (breathing) section of the lung (Fig.).
Rice. Diagram of the bronchial tree of the lung: 1 - pulmonary vein; 2 - bronchial artery; 3 - segmental bronchus; 4 - pulmonary artery; 5 - x-order bronchus; 6 - terminal bronchus; 7 - alveolar duct; 8 - alveolar sac; 9 - respiratory bronchus
The process of respiration (the body consumes oxygen and releases carbon dioxide) consists of the following stages:
external respiration (exchange of gases between the external environment and the lungs - pulmonary ventilation);
transportation of gases by blood;
cellular respiration (oxygen consumption by cells and release of carbon dioxide).
Pulmonary ventilation is possible due to the difference in pressure in the atmosphere and in pleural cavity. The decrease in pressure in the pleural cavity is associated with the presence of elastic fibers in the lungs, which prevent the lungs from being stretched by atmospheric air. The force with which the lungs strive to return to their original position is called elastic traction of the lungs. The minute volume of ventilation is equal to the product of the volume of an individual breath and the number of breaths per minute. Total lung capacity is the sum of vital capacity and residual air. The sum of the volumes of respiratory, additional and reserve air is the vital capacity of the lung (1.5-3 liters in dogs, 26-30 liters in horses, 30-35 liters in cattle).
Respiratory air is the volume of one inhalation or exhalation (0.5 liters in sheep, 5-6 liters in horses). Additional air is the volume of air that can be inhaled after a quiet breath (up to 1 liter in sheep and dogs, 10-12 liters in horses). Reserve air is the volume of air that can be exhaled after a quiet exhalation (approximately equal to additional air). Residual air is the volume of air that enters the lungs during the first breath and always remains in them (approximately equal to additional air).
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