The internal structure of a rabbit. Rabbit skeleton: structure and features. The internal structure of the urinary system

Bone and muscle tissue are the basis of the structure of the animal and allow you to make movements. The basis for this, of course, is the skeleton. In a rabbit, it consists of 212 bones, not including teeth, as well as auditory bones. In adults, the skeleton occupies 10% of the mass of the whole organism, and in rabbits - 15%.

In its structure, the skeleton of a rabbit is similar to the skeleton of other mammals. Conventionally, it can be divided into two types: axial and peripheral. The axial includes all the main bones, that is, the head and spine. The peripheral skeleton consists of the bones of the limbs.

If we consider the skull of rabbits, then in its structure it is not much different from the skull of other animals. Most of it, which is about 3/4, is occupied by the front part. Here are some of the organs of respiration and digestion. Separate parts of the skull determine the shape and size of the muzzle and differ in different breeds of rabbits.

Diagram of the structure of the rabbit's head

The spine of a rabbit can be conditionally divided into five parts: neck, chest, lower back, sacrum and tail. All of them have an unequal number of vertebrae. So, for example, their largest number is in the tail, and the smallest in the lumbar. Although the lumbar region is the largest in length, it has elongated vertebrae, which can be clearly seen in the photo below.

As for the peripheral skeleton, then, like in other domestic animals, in a rabbit it has a shoulder and pelvic region, as well as free limbs. But the difference lies in the presence of the collarbone. It connects the sternum and shoulder blade, which allows the animal to jump. It is also worth talking about the muscular system, since its development indicates the exterior and meat qualities of the animal. This system includes the muscular part of the internal organs and the body itself.

Other hematopoietic organs

Also, this animal system includes organs such as the spleen, appendix, bone marrow, lymph nodes and thymus gland. Their role is to form additional blood elements. For example, the spleen weighs no more than 1.5 grams and is responsible for regulating blood pressure. It forms lymphocytes and destroys the "old" obsolete erythrocytes. They, in turn, are created by the bone marrow. The thymus gland stimulates the formation of blood in other organs. Its mass does not exceed 2.3 grams in rabbits, but with age it decreases.

Digestive system

It is one of the most important systems that provides and maintains the nutrition of the body and its life. In rabbits, as in many other herbivores, the internal organs of this system are adapted to the processing of large amounts of bulk and roughage. The digestive apparatus is very well developed, and the entire length of the intestine occupies more than 18% of the total body weight. What is included in this system you can find out in more detail from the diagram. The first stage of food processing begins with its grinding in the oral cavity.

Teeth

Rabbit teeth have their own characteristics. Newborn animals have 16 teeth, which change from the 18th day of life. Adult rabbits have only 28 teeth, which is less than other animals. They also have 4 large incisors above and 2 below, with which the animal gnaws food. With molars, which are on the side, he crushes food. Food, crushed by teeth and moistened with saliva, is sent to the throat, then enters the esophagus and stomach.

Stomach

Rabbits have a rather voluminous (up to 200 cm3) stomach with one chamber, which is a banded internal organ. The gastric juice secreted by the glands consists mostly of hydrochloric acid and a special substance - pepsin. The total acidity is between 0.18 and 0.35%, and the activity of its enzymes is much higher than that of other animals. It is important to note that the rabbit's stomach does not digest fiber and it moves further into the intestine itself. This is where the final stage of digestion takes place.

Intestines

The intestine is made up of a thin and thick section. In the first, the main splitting of all substances occurs. Here, amino acids and other substances are absorbed, which are immediately sent to the blood. Then the food moves into the thick section, where fermentation processes take place. Here fiber is broken down and absorbed. Remaining food and waste is excreted from the body approximately nine hours after eating.

Rabbit digestive system: 1 - heart; 2 - lungs; 3 - liver; 4 - esophagus; 5 - stomach; 6 - kidneys; 7 - small intestines; 8 - large intestines; 9 - caecum; 10- bladder

Respiratory system

Enrichment of the body with oxygen is supported by the respiratory organs, namely the nose and its cavity, pharynx, trachea and lungs. In the nasal part, the air is warmed, moistened and cleaned of dust, sent through the pharynx to the trachea and then to the lungs. It is important to note that rabbits are very sensitive to the purity of the air. The high content of ammonia, dirt, dust, carbon dioxide in the air adversely affects the condition and health of animals.

Lungs

The lungs are paired organs that carry out gas exchange. Despite their very low weight (about 0.36% of the total mass), the respiratory rate in rabbits is higher than in other pets and depends on body temperature. Normally, a rabbit takes up to 282 breaths per minute, while it absorbs over 500 cm3 of oxygen. If, for example, the animal absorbed 478 cm3, then 451 cm3 of carbon dioxide will be released, which characterizes a very active gas exchange.

genitourinary system

In the rabbit, this system includes both the reproductive and urinary organs. The latter include the kidneys, ureters, and urethra. This system ensures the excretion of decay products from the body of the animal. The amount of urine depends on age and nutrition, per day can range from 110 to over 400 ml. The urinary canal itself is closely connected with the genitals, or rather, in females with a vagina, and in males with the glans penis.

kidneys

A paired organ in the form of beans, which is located on both sides of the spine in the lumbar region. The process of urine formation in the kidneys is continuous. Proteins, mineral salts and other substances break down here. The contents from the kidneys through the ureters enter the bladder, where it accumulates until a reflex reaction of excretion occurs.

Sex organs

In male rabbits, the reproductive apparatus is represented by paired testes, the vas deferens, adnexal glands, and the penis itself. Testes with appendages weigh about 6 grams and are slightly elongated. Up to 3 months in rabbits, they are in the inguinal canals and only then descend into the scrotum. The male during one mating is able to allocate up to 3.5 ml of sperm.

In females, the reproductive system includes the uterus, ovaries, oviduct, vagina, and genital opening (slit). The ovaries produce eggs that are released into the oviduct during ovulation. The uterus in rabbits is double and consists of two horns. The release of the egg, that is, ovulation, begins 10-12 hours after insemination. All this time the sperm is inside the vagina.

Endocrine glands

This system includes the thyroid gland, pituitary gland, adrenal glands, pancreas, as well as the testes and ovaries. These glands do not have excretory tracts, so hormones are released directly into the blood. The thyroid gland creates a special hormone thyroxine, which regulates metabolic processes, development and growth of the body. The adrenal glands regulate water and fat metabolism with the help of a hormone. The largest number of hormones secretes the pituitary gland, it is about 10, which are involved in many life processes.

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Just by looking at a rabbit, one can already indicate the main characteristic feature of representatives of the class of mammals - this is a hairline covering the entire body of the animal. Indeed, hair, or wool, is unique to mammals, just as feathers are unique to birds. Only in some mammals are certain parts of the body, instead of hair, covered with real horny scales, such as the tail of mice or rats.

In most mammals, like kangaroos, the hairline is heterogeneous. They have coarse, long hair, called guard hair, and soft, short hair - undercoat, or down.

For winter and summer, rabbits, like all mammals, molt, that is, their hair falls out and is replaced by a new hairline. Mammals acquire especially thick hairline after the autumn molt for the winter period.

Rabbit body structure

Like bird feathers or reptile scales, rabbit hair is made up of horny matter. Each hair is a thin horny cylinder, which at one end is deepened into the skin into the hair bag, where it forms a small hair follicle. This is where the hair grows from.

The ducts of the sebaceous glands that secrete fat open into the hair bag. The hair is lubricated with this fat, thanks to which the wool becomes soft, and the surface of the rabbit's skin does not dry out.

Warm air is trapped between the hairs, which protects the rabbit's body from rapid cooling. At the same time, in the heat, the body of mammals is also protected from overheating: there are sweat glands in the skin that release moisture - sweat - onto the surface of the skin, which helps to cool the body.

In appearance, rabbits resemble hares, from which they differ in smaller size and a different color of fur.

The relatively short body of a rabbit ends in a small head with very long movable auricles, which only mammals have. Listening, the rabbit turns them in different directions and picks up sound waves well.

Rather large rabbit eyes, located on the sides of the head, have only two eyelids - the upper and lower. Mammals do not have a third eyelid (nictitating membrane), like in birds.

Eyelashes are located along the edges of the eyelids, protecting the eye from clogging.

Noteworthy is the upper lip of the rabbit, which is cut in two, which makes it possible for him to gnaw on the standing stems of plants. On the sides of the lips there are long coarse hairs that form the so-called rabbit whiskers and serve as an organ of touch. Such whiskers are of particular importance in those animals that are nocturnal (for example, in a cat).

At the front end of the muzzle of the rabbit there are slit-like nostrils leading to the nasal cavity, where the olfactory nerves branch. This is the organ of smell, which in most mammals plays a very important role in the search for food.

The limbs of a rabbit, like all mammals, are two pairs. The rabbit moves by jumping, pushing off the ground with strongly developed hind limbs, which are almost twice as long as the front ones.

Jumping, the rabbit stands on fingers, at the ends of which there are claws. Rabbits have five toes on their front legs and four on their hind legs.

Hair, claws, nails and hooves (in different mammals) are horny formations of the skin.

On the ventral side of the rabbit, there are five pairs of nipples, into which the ducts of the mammary glands open. The mammary glands produce milk, with which the females feed the cubs until they switch to independent nutrition. Mammary glands are found only in mammals and their number in different animal species is different.

Breath

In the chest cavity of the rabbit, on both sides of the heart, there are lungs of a spongy structure, which are better developed than in animals of other classes of vertebrates.

The lungs of mammals are much more voluminous than those of birds. They lie freely in the chest cavity, and are not attached to the walls of the body, as we see in birds.

When a rabbit breathes, the air entering through the nostrils and nasal cavity is cleaned of dust in it, after which it enters the pharynx and larynx. On each side of the anterior wall of the larynx, two vocal cords are stretched. The vibrations of these ligaments of water by the influence of the exhaled air cause one or another sound, depending on the degree of tension of the ligaments.

Passing through the larynx, the air enters the trachea, and then through the two bronchi passes into the lungs.

In the lungs, the bronchi branch into thin tubes - bronchioles, which end in pulmonary vesicles. The walls of the pulmonary vesicles are densely braided with capillaries. These are the thinnest vessels that penetrate all the organs and tissues of animals: their diameter is much smaller than the diameter of a hair. Their last branches can be seen only at high magnification of the microscope. Through the thinnest walls of the capillaries there is an exchange of gases in the blood. Here, the blood absorbs oxygen from the air and gives carbon dioxide to the pulmonary vesicles.

Both inhalation and exhalation of air is carried out using the ribs and the diaphragm.

Inhalation occurs due to the contraction of special muscles, which, by raising the ribs and straightening the diaphragm, increase the volume of the chest, and air is drawn into the lungs. When the ribs are lowered, the ribcage narrows and air is forced out of the lungs. This is how exhalation happens.

Circulation in a rabbit

Moving through the body of a rabbit, blood, just like in birds, passes through two circles of blood circulation - large and small. Oxidized in the lungs, blood in mammals does not mix in the heart with blood saturated with carbon dioxide, as occurs in lower vertebrates (amphibians, reptiles), which depends on the structure of the heart typical of them.

The heart of a rabbit, like that of all mammals and birds, is four-chambered, that is, it consists of two atria and two ventricles.

Such a perfect circulatory system provides enhanced activity of all organs of the rabbit and contributes to the formation of a large amount of heat in his body and maintaining a constant temperature. This means that mammals, like birds, belong to warm-blooded animals. The normal body temperature in mammals is from +37 to +40 degrees, in rabbits it is +39.5 degrees.

reproduction

The reproductive organs of rabbits are very similar to those of birds. In males, these are the testes, which produce male germ cells - gum, in females - the ovaries, in which female germ cells are produced - eggs. But if in birds fertilized eggs go out through the oviduct and for the further development of the embryo it is necessary to incubate them, then in mammals, due to the fact that their embryo develops inside the mother's body, the process of reproduction occurs differently.

In mammals, the oviducts do not open outwards, as in birds (into the cloaca), but, connecting with each other, form a special extension - the uterus, which in a rabbit has the shape of a bag with two long outgrowths. Eggs enter these outgrowths, which are a continuation of the oviducts, from the ovaries, and all further development of the embryos occurs in the uterus.

Eggs of mammals are very small: in rabbits, the egg diameter is only 1/9 mm, and its size is 3 thousand times smaller than a frog egg and 15 million times smaller than a chicken egg.

The embryo in mammals is firmly connected by its membranes to the wall of the uterus with the help of the placenta, through which it is supplied with the mother's blood.

Together with the blood, the fetus also receives nutrients and oxygen dissolved in the blood from the mother's body. In its development, the mammalian embryo, just as we have seen in reptiles and birds, passes through the fish-like stage, which is characterized by the presence of gill slits. This fact once again confirms the origin of all these terrestrial animals from low-organized fish-like forms.

30 days after the fertilization of the eggs, the development of the embryos in the uterus stops and the rabbits are born. Newborn rabbits are completely unsuited to independent living, they are blind, naked, helpless and for a long time (about three weeks) remain in the nest near their mother, who feeds them with her milk.

At the same time, among mammals there are those (cow, horse, deer, sheep) in which newly born cubs are sighted, covered with thick hair, and a few hours after birth they are already able to move independently.

The anatomical structure of rabbits is very similar to the body structure of other mammals, but still has its own characteristics.

Today we will consider the structure of the skeleton, internal organs and the main body systems of these animals.

Skeleton

In the skeleton of a rabbit, there are 112 bones; it is necessary to protect the internal organs and carry out movements. The weight of the skeleton in adults is about 10% of the total body weight, in young animals - 15%. The bones that make up the skeleton are connected by cartilage, tendons, and muscles. The rabbit skeleton consists of peripheral and axial.

Did you know? In the wild, rabbits live very little - only 1 year, while domestic individuals sometimes live up to 12 years.

Peripheral

This part of the skeleton includes the bones of the limbs:

1. Thoracic, consisting of the humerus, shoulder blades, hands, forearm. The hand has a certain number of bones: metacarpal - 5, carpal - 9 fingers.
2. Pelvic, having a pelvis, ilium, ischium and pubic bones, lower legs, hips, feet, 4 fingers and 3 phalanges.

Axial

This part of the skeleton consists of the main bones - the skull and ridge.

1. The skull, consisting of the brain and facial sections. The skull is characterized by the presence of movable bones, which are interconnected by certain seams. In the brain there are 7 bones, represented by the parietal, occipital, temporal and others. The facial section has the maxillary, nasal, lacrimal, zygomatic, palatine bones. The shape of the skull is elongated, there is an external resemblance to the skull of other mammals. The main part of the skull is occupied by organs that perform breathing and eating.
2. The trunk, characterized by the presence of the spinal column, sternum, ribs. The ridge is divided into 5 sections or departments. The spine of a rabbit is quite flexible, due to the presence of menisci that connect the vertebrae.

The main parts of the spine are:

• cervical, consisting of 7 vertebrae;
• thoracic, consisting of 13 vertebrae, which are connected with the help of ribs and form a chest that contains the heart and lungs;
• lumbar with 7 vertebrae;
• sacral with 4 vertebrae;
• caudal with 15 vertebrae.

Important! Meat breeds of rabbits have vertebrae wider than normal, which often helps breeders in choosing the right animal when buying.

The extent to which the musculature is developed in rabbits makes it possible to prematurely form a concept about the features of the appearance and taste of meat.

The muscular system of rabbits is represented by:

• the musculature of the body, which, in turn, consists of striated muscles, covering absolutely all the muscles of the body;
• the muscles of the internal organs, which covers the smooth muscles that cover the respiratory organs, the organs of the digestive system, and the vascular walls.

Small rabbits have an underdeveloped muscular system, which occupies less than 20% of the total weight of the animal, and as they grow older, the muscles grow and reach 40%.

Nervous system

The nervous system of rabbits consists of:

• central, represented by the brain and spinal cord;
• peripheral, represented by nerves of skeletal muscles, blood vessels and skin.

The hemispheres of the brain of this animal are separated by a small groove, the brain has three sections, represented by the middle, posterior, oblong, each of which is necessary to perform individual functions. For example, thanks to the oblong section, the work of the respiratory organs and circulatory processes takes place.

The spinal canal allows the spinal cord to settle down, the beginning of which is in the brain, and the end in the seventh cervical vertebra. The weight of the spinal cord is 3.5 g. The peripheral section consists of spinal, cranial nerves and nerve endings.

This system covers all processes in the rabbit's body that deal with blood, that is, the hematopoietic organs, the lymphatic system, veins, arteries and capillaries. Each element is necessary to perform certain functions.

The body of a rabbit contains an average of 250-300 ml of blood. In winter, the animal is characterized by a low body temperature, which is +37 ° C, in summer it is elevated - +41 ° C.

The rabbit heart has 4 chambers, consisting of two ventricles and two atria. Its weight is 7 g, its position is the pericardial serous cavity. The normal pulse for an animal is within 140 beats per minute.

Important! If the rabbit's body temperature rises by 3 degrees in summer and reaches +44 °C, then he will die.

Digestive system

This system in the body allows the processing of food consumed by the rabbit. The full cycle - from ingestion to processing of food in the gastrointestinal tract - is three days.

Teeth

Being born, the rabbit already has 16 teeth, in the process of growth, at 3 weeks, there is a change of milk teeth to molars. Adults have 28 teeth, their growth is stable throughout life.

The jaws consist of large incisors, designed for chewing solid food, and molars, which are necessary for grinding other food. Food that has been crushed by teeth is transported to the pharynx, the next stage is transportation to the esophagus and stomach.

Stomach

In a rabbit, this is a hollow organ with a volume of about 200 cubic meters. cm, which is capable of producing gastric juice. Gastric enzymes in a rabbit are highly active when compared with other animals. The fiber that the eared ones consume is not digested by the stomach, it goes to the intestines.

Intestines

The remnants of food that the stomach could not cope with enter the intestines, which carry out the final processes of digestion.

The organ is represented by:

1. The small intestine, which is engaged in the breakdown of substances, including amino acids, which directly enter the bloodstream.
2. The large intestine, which is involved in fermentation processes. Food that has not been digested and digested comes out under the guise of feces, its amount is 0.2 g per day. In the daytime, the feces are characterized by a solid form, at night - soft. Feces that are excreted at night are eaten by animals, due to which they receive the necessary proteins, vitamins K and B.

Respiratory system

The respiratory organs in a rabbit are represented by the nose, pharynx, trachea and lungs, which allow the body to be supplied with oxygen. Inhaling the air in the nose, it is heated, moistened, cleansed of impurities. Then it begins to advance into the pharynx, trachea and lungs.

Rabbits breathe faster than other mammals. The norm is 280 breaths per minute. Ushastiki have accelerated gas exchange processes: consuming about 480 cubic meters. cm of oxygen, they release 450 cu. see carbon dioxide.

sense organs

Individuals have the following sense organs:

1. Smell, which is possible due to prescription cells located deep in the nose. Cells have 11 hairs that respond to a variety of scents. Thanks to the sense of smell, individuals choose a mate for mating, and the female can distinguish her cubs from strangers by smell.
2. taste, which is caught by special papillae covering the tongue.
3. touch, the functioning of which occurs with the participation of the sensitive skin located on the eyelids, lips, back and forehead. Thanks to this sense, pets can orient themselves in space, perceive temperature changes and avoid overheating, and respond to painful stimuli. Thanks to the antennae, animals can move around at night when the cage is completely dark. Hairs located above the eyelids allow rabbits to navigate and sense obstacles.
4. By sight, which is provided by the eyes, consisting of an eyeball in the form of a ball connected to the brain. Rabbits can distinguish colors, and a feature of vision is farsightedness and the ability to navigate in the dark.
5. by rumor, due to the large ears that allow rabbits to identify and recognize sounds well.

genitourinary system

This system in the body of rabbits consists of the genital and urinary organs. Urinary organs are necessary for excretion of decay products from the body. The amount of urine excreted directly depends on the age and nutrition of the animals. One individual can excrete no more than 400 ml of urine per day. The urinary canal is located very close to the genital apparatus.

Did you know? Communication between animals is possible thanks to high-frequency sounds. To catch some of them, individuals can turn their ears in different directions.

Mammals have two oval kidneys that lie in the lumbar region and are necessary for the breakdown of proteins, mineral salts and other substances.

Rabbit (live) blood is distributed approximately as follows: in the muscles about 1 / 4 of all blood, in the liver - about 1 / 4, in the heart and large vessels - about 1 / 4 and 1 / 4 in all other organs.

The total amount of blood in rabbits is 32 - 67 ml (from 4.5 to 6.7% of their weight). blood pH 7.25 - 7.43. Specific gravity 1.0425. Erythrocytes in 1 ml of blood in newborn rabbits are 4.5 million, in adults on average about 5 million (from 2.76 to 6.32 million), in males they are 7-8% more than in females. Leukocytes in 1 ml of blood on average 8800 (from 6000 to 10000), platelets 300 - 800 thousand.

100 ml of blood of rabbits contains 8.4 - 12.4 g of hemoglobin, in males it is 2 - 3% more.

The features of the rabbit vessels are: a sharply curved and low-lying aortic arch, a loose type of discharge of the main trunks from the aortic arch, the presence of the left anterior vena cava, etc. There are sharp features in the course of the location of the arterial and venous vessels, for example, the subcutaneous location of the veins etc.

The lymphatic system of rabbits also has characteristic differences, primarily related to the lymph nodes, which are large in a rabbit, but not numerous.

The heart, like the lungs, is poorly developed in a rabbit. The number of heartbeats in rabbits is 120-160 per minute.

The structure of the heart

The main distinguishing features in the structure of the rabbit heart are: the comparative isolation of the sinus region from the right atrium with the preservation of sinus valve remains on their border, the penetration of individual myocardial fibers in the walls of the pulmonary veins far into the lungs, weak differentiation of the atrioventricular valves ventricular valves, the presence in the embryonic period of distant prototypes of human Eustachian and Thebesian valves, etc.

Location of the heart

The rabbit's heart is somewhat displaced to the left and obliquely elongated along the inner surface of the sternum. It extends from the posterior margin of the 2nd rib to the posterior margin of the 4th rib (sometimes the anterior margin of the 5th). material from the site

The location of the heart in a rabbit has its own characteristics. Due to the sharply narrowed anterior part of the thoracic cavity and a certain displacement of the heart forward compared to other animals, it lies in the middle mediastinum, at the very beginning of the chest, in a very cramped position. Because of this, it is located directly under the trachea, which is strongly pressed into its base. The rabbit's heart fills almost the entire anterior part of the chest cavity. Therefore, the aortic arch is very low, steeply curved and pulled forward, and the aorta itself is displaced sharply to the left, located to the left of the trachea and going into the upper edge of the left lung.

All this is reflected in the topographic relationship of the heart with the tops of the lungs. So, the end of the right apex of the collapsed lungs lies at the level of the anterior contour of the heart, and the left apex usually lies in the middle of its base. However, in the natural, straightened state of the lungs, the heart is almost completely covered from the sides by their lobes, especially on the right, which is explained by the rounded shape of the chest in the rabbit. Only from below, in the region of the anterior third, the heart, adjacent to the sternum, is free from the lungs surrounding it. This is clearly seen on the entrails extracted from the chest cavity as a whole, if the lungs are previously fixed in a straightened position.

The heart of rabbits is the central organ of the cardiovascular system, which, like a motor, moves the blood of rabbits through the vessels.

The circulatory system of rabbits includes the heart - the central organ that promotes the movement of blood through the vessels - and blood vessels - arteries (distribute blood from the heart to organs), veins (return blood to the heart) and capillaries (carry out the exchange of substances between blood and tissues) . The vessels of all three types along the way communicate with each other through anastomoses that exist between vessels of the same type and between different types of vessels. There are arterial, venous or arteriovenous anastomoses. At their expense, networks are formed (especially between capillaries), collectors, collaterals - lateral vessels that accompany the course of the main vessel.
Rabbit heart - the central organ of the cardiovascular system, which, like a motor, moves the blood of rabbits through the vessels. This is a powerful hollow muscular organ located obliquely in the mediastinum of the chest cavity, in the region from the 3rd to the 6th rib, in front of the diaphragm, in its own serous cavity.
The heart of rabbits is four-chamber, from the inside it is completely divided by the interatrial and interventricular septa into two halves - the right and the left, each of which consists of two chambers - the atrium and the ventricle. The right half of the heart of rabbits, according to the nature of the circulating blood of rabbits, is venous, poor in oxygen, and the left half is arterial, rich in oxygen. The atria and ventricles communicate with each other through the atrioventricular openings. The embryo (fetus) has an opening through which the atria communicate, and there is also an arterial (botall) duct through which blood from the pulmonary trunk and aorta mixes. By the time of birth, these holes are overgrown. If this does not happen in a timely manner, the blood mixes, which leads to serious disturbances in the activity of the cardiovascular system.
The main function of the rabbit heart is to ensure a continuous flow of rabbit blood in the vessels. At the same time, blood in the heart of rabbits moves in only one direction - from the atria to the ventricles, and from them to the large arterial vessels. This is provided by special valves and rhythmic contractions of the muscles of the heart - first the atria, and then the ventricles, and then there is a pause and everything repeats again.
The heart wall of rabbits consists of three membranes (layers): endocardium, myocardium and epicardium. The endocardium is the inner shell of the heart of rabbits, the myocardium is the heart muscle of rabbits (it differs from skeletal muscle tissue by the presence of intercalated crossbars between individual fibers), the epicardium is the outer serous membrane of the heart. The heart of rabbits 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 its functioning. The walls of the left ventricle are 2-3 times thicker than the right. The heart rate largely depends on both the condition of the animal and its age, physiological state and ambient temperature. Under the influence of heart contractions (due to blood flow), there is a consistent contraction of blood vessels and their relaxation. This process is called the pulsation of the blood, or the pulse of the rabbits. The pulse of rabbits is determined by the femoral artery or brachial artery for 0.5-1 min (four fingers are placed on the inner surface in the region of the femoral canal or shoulder, and the thumb is placed on the outer surface of the thigh or shoulder). In newborn rabbits, the pulse rate is 280-300 beats / min, in an adult - 125-175 beats / min.