The circulatory system of mammals. The anatomical structure of the rabbit

Signs indicating the relatively primitive nature of the anatomical structure of rabbits are: the presence of the orbital salivary gland, the presence of a spiral fold in the caecum, absent-mindedness of the pancreas, a reduced state of the omentum, a simplified paired scrotum with wide and short inguinal passages , into which the testes can enter, a straight, backward-directed penis, a double uterus and a number of others.

Digestive system: see Rabbit digestion

Respiratory system: see Rabbit respiratory system

Nervous system: see Rabbit nervous system

Rabbit urinary system

rabbit teeth

The structure of the teeth is great importance in the taxonomy of mammals. A newborn rabbit has 16 milk teeth. Among distinctive features the presence of two pairs of incisors in rabbits should be highlighted. A large space separating the molars from the incisors is characteristic. The teeth of rabbits are completely covered with enamel, unlike rodents, which have inside there are no enamel incisors. The incisors of a rabbit have the peculiarity of continuously growing throughout the life of the animal.

Rabbit teeth formula:

• dairy - I 2 C 0 P 3 / I 1 C 0 P 2 × 2 = 16;
• constants - I 2 C 0 P 3 M 3 / I 1 C 0 P 2 M 3 × 2 = 28.

Age-related changes in the teeth of rabbits are characterized by a change in the crowns of milk teeth and their change to permanent ones. Rabbits are born with milk teeth, which are replaced by permanent ones by the 18th day after birth. The permanent teeth are long-crowned: in the upper arcade there are two powerful incisors. Behind is a pair of small incisors supporting large incisors. In the lower jaw there are two large incisive teeth. There are no fangs. Premolars 3 on the upper jaw on each side and two on the lower jaw. Upper and lower molars 3 on each half oral cavity. The teeth wear out and protrude regularly from the jaws.

Structure internal organs and the skeleton of a rabbit are similar to the anatomy of other vertebrates, but still there are some differences. Today we will take a closer look at all the components of the rabbit skeleton and the features of other vital organs - such information will be useful to all novice farmers. Let's get started.

The skeletal system of the animal performs both supporting and protective functions, and the rabbit skeleton consists of more than two hundred bones. So, in an adult rabbit, bones occupy about ten percent of the body weight, and in a rabbit, up to fifteen percent of the body weight. This whole system is interconnected by cartilage, muscle tissues and tendons.

Note! In rabbits of meat and meat-skin breeds, the bones occupy a smaller volume relative to their weight.

Peripheral

This group includes:

1. Forepaws (limbs of the sternum). They consist of the forearm, shoulder bone, belt and hands. Each hand has a certain number of bones: five metacarpals and five carpals (fingers).
2. Hind legs (pelvic, lower limbs). Consist of the pelvis, ilium, ischium, thighs, feet (four fingers and three phalanges).

The bones of the sternum and the girdle are connected with each other by the collarbone, which allows the animals to jump. The spine of these individuals is a weak point, as are the weightless bones of the limbs, so the rabbits often get injured on the back or legs.

Axial

This group includes the bones of the skull and spine:

1. Skull box. The facial bones are movable, interconnected by peculiar sutures. The bones of the brain include: the temporal bone, the bone of the occiput, the bone of the crown. The facial section includes: the bone of the upper jaw, as well as the nasal, palatine, lacrimal bones. The skull in rabbits is oblong, like most small mammals. The main part is occupied by the organs of the respiratory and digestive systems.
2. Body (chest bone, spine, ribs). The spine in an adult rabbit consists of several parts, which we will consider in more detail. Plasticity is provided to him by cartilaginous pads that act as shock absorbers. They connect with each other.

Note! The widest spine is found in individuals of meat breeds. The value of such characteristics allows the farmer to make the right selection of animals for breeding.

muscles

Taste qualities of meat products and appearance rabbits depend precisely on the structural features of the muscular system. Muscle contraction occurs under the influence of nerve impulses.

There are such types of muscles:

1. Muscles of the body. Represented by striated muscles. All muscles belong to this group.
2. Muscles of the viscera. They are smooth muscle. For example, capillary walls, the walls of the respiratory system or the digestive system.

The lifestyle of rabbits does not involve training, so their muscles are not sufficiently saturated with the oxygen-binding protein myoplasma. Their meat has a light pink color, but is slightly darker in the limbs.

Immediately after birth, babies have a poorly developed muscle system, which makes up 22% of the total mass. With the process of growing up, it increases to 42%.

Important point! The meat of adult animals is slightly higher in calories than the meat of young animals. About that, you can read in our special article.

Prices for cages for rabbits

Rabbit cage

Nervous system

This system consists of:

• organs of the central nervous system;
• skeletal muscle nerves skin, capillaries (peripheral system).

The brain of rabbits, like that of all living beings, is divided into two hemispheres: right and left, it is located inside the skull. At the same time, the brain still has several sections (central, posterior and bulb). Each of them has a functional purpose. For example, the bulbus regulates the functioning of the respiratory system and of cardio-vascular system.

Inside spinal canal is the center of the nervous system, which runs from the brain to the 7th cervical vertebra. Its weight is just over three grams. It consists of gray and white matter.

The cardiovascular system

This system includes everything that has a connection with the blood: hematopoietic organs (spleen), The lymph nodes, arteries and any vessels. Each of them is responsible for a specific function. For example, the spleen, which has a mass of just over a gram, regulates arterial pressure. The function of the bone marrow is to produce red blood cells.

Note! The thymus is responsible for stimulating hematopoiesis. In newborn babies, it is small, about two grams, but increases over time.

About 275 ml of blood circulates in the body of these animals. The body temperature of healthy individuals in the cold season is 38 degrees, and in the warm season - 39-40 degrees. When too high temperature in rabbits, hyperthermia occurs, which leads to death. The heart of rodents consists of 4 chambers, paired ventricles and atria, and its mass is about 7 grams. Their heart rate is up to 155 beats per minute.

Digestion

The organs of the digestive system allow you to break down any food that enters the body of rabbits. Products pass through the entire gastrointestinal tract within three days.

Newborn individuals have sixteen milk teeth, but after a while they fall out and are replaced by molars. The grown rabbits already have twenty-eight molars. They grow gradually throughout the life of animals. They have large incisors that allow rabbits to handle tough food.

After swallowing, food first enters the larynx, and from there into the esophagus and stomach. The stomach is empty inside, its volume is up to two hundred cubic centimeters, it is necessary for the production of hydrochloric acid. Experts note that the stomach enzymes in rabbits are more active compared to other mammals. Even plant food is not broken down here, it immediately enters the intestines, where the final process of digestion takes place.

Table number 1. The structure of the intestines of rabbits.

Video - Features of the digestion of rabbits

Feed prices for rabbits

Compound feed for rabbits

Respiratory system

To respiratory system rodents include the nose, larynx, trachea and a paired organ - the lungs. All these organs provide animals with air. After inhalation, it passes through the stage of filtration, moisturizing, heating, then enters the throat, then into the lungs through the connecting tubes.

It is important to remember that rabbits breathe more intensively than other animals. They are able to take about 280 breaths in 60 seconds. In addition, they have an active process of gas exchange.

sense organs

Rabbits have the following sense organs:

1. Sense of smell (perception of smells). Receptors are responsible for this process, which look like small hairs (located in the nasal passage). Thanks to what animals can feel any aromas. So, the rabbit will be able to distinguish her cubs from strangers.
2. Taste. Special receptors that are located on the tongue and palate help to recognize taste.
3. Touch (tactile perception). Sensitivity is observed in rabbits in the skin of the eyes, crown, mouth and back. Animals react to pain, temperature, orient themselves in space.
4. Vision. Rabbits see this world in color. Their main apples are rounded, they are connected to the head. Rabbits see a little better at close range.
5. Hearing. Rabbits have noticeable ears, thanks to which they can hear everything that happens around them. They communicate with each other with special sounds, turning their ears to the sides.

Note! Rabbit breeds with drooping ears have poor hearing. They were bred artificially, so they will not survive in their natural habitat.

Note! When moving in complete darkness, the whiskers of rabbits play an important role, which help them navigate in space.

excretory and reproductive systems

This system represents both the reproductive and urinary organs. The functions of the latter is to remove residual products from the body. The amount of urine that accumulates per day depends on age characteristics. In 24 hours, the body of each rabbit produces up to 380 ml of urine, it is saturated with uric acid and ammonia. The urinary canal is located next to the organs of the reproductive system.

These animals have two kidneys, each of which is located in the lower back. They are necessary for the breakdown of proteins, salts and other substances.

Urine is constantly formed, first from the kidneys moves through the connecting tubes, and then is brought out. Healthy rabbits have golden brown urine. Excessively yellow or too cloudy urine is a sign of diseases in the body.

reproductive organs

In heterosexual animals, organs have some differences. Rabbits reproductive system consists of the following:

• two testicles;
• spermatic cords;
• appendages;
• penis.

In females, the reproductive system is represented by the following organs:

• uterus;
• ovaries;
• egg duct;
• vagina.

The reproductive organ of the rabbit is divided into two parts. This feature allows you to simultaneously bear cubs from different male producers.

In order for mating to occur between animals, the female is sent to the cage to the male when signs of sexual hunting occur. In addition, a week before this process, their body is saturated with special vitamin feeds. It is useful to feed the male with boiled potatoes during this period.

Video - Rabbit mating: features

Endocrine glands

This system includes the following organs:

Hormones enter immediately into the bloodstream, since they have no other ways to withdraw. The adrenal glands are responsible for the regulation of water-fat metabolism in the body. The lack of certain glands leads to various disorders in the body.

Milk glands

All rabbits have mammary glands and nipples, only in rabbits they are in the form of rudiments and are small protrusions above the skin.

The development of the gland is present in lactating females. They look like white formations protruding above the skin, located on both sides of the belly. Each mammary gland passes into the nipple, with milk passages. Depending on the size of the rabbit and her breed, there are from 4 to 12 pairs of nipples.

How to choose a healthy rabbit?

For breeding, it is important to choose only strong, healthy representatives of a particular breed, so novice farmers need to be careful when buying pets. It should be borne in mind that unscrupulous sellers often try to sell sick or defective animals.

Choosing a rabbit: step by step instructions

Step 1. It is necessary to observe the behavior of rabbits. These animals are active, move around the cage, and healthy rabbits will definitely not sit in one place.

Bald spots on the body - a sign of improper maintenance

Note! If possible, the seller should be asked about the vaccination of the livestock. Rabbits often die from viral and infectious diseases during the epidemic, so the rabbits are vaccinated in advance.

Only knowing the features of the anatomy of rodents, it is possible to recognize the presence of a pathological process in the body in time and help the animal. Therefore, information about the structure of these rodents is mandatory for all rabbit breeders. We hope you have read it carefully.

Musculoskeletal system. The skeleton of mammals consists of the same sections as those of other terrestrial vertebrates: the skull, spine, trunk skeletons, belts and free limbs (Fig. 193).

Rice. 193. Skeleton of a mammal: 1 - upper jaw; 2- lower jaw; 3 - skull; 4 - teeth; 5 - cervical vertebrae; 6 - thoracic vertebrae; 7 - lumbar vertebrae; 8 - tail vertebrae; 9 - ribs; 10 - scapula; 11 - shoulder; 12 - forearm; 13 - brush; 14 - pelvic bone; 15 - thigh; 16 - lower leg; 17 - foot

The bones of mammals are strong, many grow together. The skull is large, consists of a smaller number of bones than in reptiles, since many fuse even in the embryonic period. The jaws are strong, armed with teeth, which are located in the recesses - the alveoli.

The spine consists of the following five sections: cervical (seven vertebrae), thoracic (twelve vertebrae), lumbar (six to seven vertebrae), sacral (four fused vertebrae) and tail section from a different number of vertebrae in different mammals. The vertebrae are massive, with flattened surfaces of the bodies. To the vertebrae thoracic the ribs are attached, part of them is connected to the sternum, forming chest. The girdle of the forelimbs consists of paired clavicles and paired shoulder blades. The bark-coids (crow bones) are reduced in most animals. In horses and dogs, in which the legs move only along the longitudinal axis of the body, the clavicles are also reduced. The girdle of the hind limbs (pelvic girdle) consists of two large pelvic bones. Each of them arose during the fusion of the pubic, sciatic and ilium. The pelvic bones fuse with the sacrum.

Mammals have a complex system of muscles. The muscles that move the limbs are the most developed. They begin on the bones of the belts and are attached to the bones of the free limb. Long tendons fit the bones of the foot and hand, which ensures good mobility of the limbs, expanding their adaptive (adaptive) capabilities.

The intercostal respiratory muscles are well developed, the contraction of which raises and lowers the chest. There are muscles that connect to the skin: for example, facial muscles, the contraction of which causes twitching of the skin, movement of the coat, vibrissae.

In all mammals, the chest cavity is separated from the abdominal cavity by a muscular septum - the diaphragm. It enters the chest cavity with a wide dome and is adjacent to the lungs.

Lab #10

Topic. The structure of the skeleton of mammals.

Target. To study the structural features of the skeleton of mammals.

Equipment: tweezers, magnifier, skeleton (and parts thereof) of a rabbit (cat, rat).

Progress

1. Consider the general structure of the skeleton. Find its parts: skeletons of the head, torso, limbs. Pay attention to the connection of the bones with each other.
2. Examine the skeleton of the skull. Pay attention to the size of the braincase, bone connections, differentiated alveolar teeth.
3. Determine the parts of the spine and their structural features.
4. Consider the structure of the chest, remember its significance for the animal.
5. Consider the structure of the skeletons of the belts and free limbs - front and rear. Find and name their main parts. Consider muscle attachment points.
6. Find similarities and differences in the structure of the skeletons of mammals and reptiles.
7. Write down your conclusions in a notebook, make the necessary drawings.

Nervous system. Central nervous system mammals consists of the same departments as in other vertebrates (Fig. 194). The most developed forebrain, which has large hemispheres. The surface of the hemispheres is formed by several layers nerve cells- the so-called bark.

Rice. 194. Nervous system of a mammal: A - general plan of the structure: 1 - brain; 2- spinal cord; 3 - peripheral nerves; B - rabbit brain: 1 - olfactory lobes of the forebrain; 2 - hemispheres of the forebrain; 3 - convolutions of the cortex; 4 - diencephalon; 5 - midbrain; 6 - cerebellum; 7 - medulla oblongata

In mammals with relatively simple behavior (rabbits, mice), the hemispheres are smooth, while in predatory mammals and primates with complex behavior, the cerebral cortex has numerous convolutions (folds) and grooves that increase their surface. The large hemispheres of the forebrain cover the diencephalon and midbrain from above. The cerebellum is well developed, where the centers of coordination of movements are located.

The peripheral nervous system, like that of other vertebrates, is represented by twelve pairs of cranial nerves (departing from the brain) and numerous nerves extending from the spinal cord. Powerful nerve trunks are sent from the spinal cord to the fore and hind limbs.

Of the sense organs in animals, the most developed sense of smell, hearing, vision. The parts of the brain associated with the olfactory, auditory and visual analyzers are well developed.

The more complex structure of the musculoskeletal and nervous systems of mammals, in comparison with reptiles, indicates their progressive development, further differentiation in the vertebrate series, and enormous adaptive capabilities.

Digestive system in mammals it is more complex than in reptiles (Fig. 195). The mouth is surrounded by fleshy lips that make it easier to grab and hold food. The teeth are differentiated (subdivided into groups) into incisors, canines, premolars and molars. In representatives of different families, they are developed differently depending on the method of feeding and the nature of the food. So, rodents and hares have well-defined incisors, predators have fangs, etc.

Rice. 195. Internal structure of a rabbit (female): 1 - trachea; 2 - esophagus; 3 - heart; 4 - lungs; 5-stomach; 6 - caecum; 7 - liver; 8 - spleen; 9 - small intestine; 10 - pancreas; 11 - kidney; 12 - large intestine; 13 - ovary; 14 - uterus; 15 - oviduct; 16 - bladder

Between the teeth and lips is the vestibule of the mouth. Rodents and monkeys have cheek pouches in which they carry food. Animals tear off food and chew with their teeth, abundantly wetting with saliva. Saliva enzymes act on complex sugars (starch, fiber), breaking them down to simpler compounds. The food bolus passes into the pharynx, esophagus and enters the stomach (Fig. 196, A). Most mammals have a simple stomach: it consists of one chamber. In its walls are glands that secrete digestive substances and acid that digest proteins.

Rice. 196. Schemes of the structure of the digestive systems of mammals: A - general plan of the structure (rabbit): 1 - mouth; 2 - oral cavity; 3 - pharynx; 4 - esophagus; 5 - stomach; 6 - liver; 7 - pancreas; 8 - small intestine; 9 - large intestine; 10 - caecum: 11 - rectum; 12 - anus; B - the structure of the stomach of a ruminant artiodactyl: 1 - a scar; 2 - grid; 3 - book; 4 - rennet

In ruminant artiodactyls, the stomach is complex, consisting of four sections - a scar, a mesh, a book and an abomasum (Fig. 196, B). Only the last of these is actually the stomach. The previous sections are extensions of the esophagus and serve to ferment food. Here, under the influence of protozoa, bacteria and yeast, indigestible fiber is processed. A cow secretes up to 50 liters of saliva per day, and food from the stomach is periodically burped and chewed with teeth (hence the name "ruminant"). In the intestine, food is exposed to enzymes secreted by the digestive glands located in the intestinal wall and supplied from the liver and pancreas. They affect all food groups: proteins, fats and sugars. Digested food is absorbed into small intestine, and undigested residues enter the large intestine, where they form stool removed outside.

Respiratory system consists of the same departments as in reptiles: pathways and lungs (see Fig. 195). The lungs of animals are more complex than those of reptiles, they have a large surface that provides perfect gas exchange.

The trachea divides into two bronchi, which enter the lungs and branch many times here. The thinnest branches are the bronchioles. They end in pulmonary vesicles, or alveoli, whose respiratory surface is 50-100 times larger than the body surface. The alveoli are richly entwined with blood capillaries. This is where gas exchange takes place. Carbon dioxide from the blood is released into the alveoli due to the pressure difference, and oxygen enters the capillaries from the alveoli, combines with the hemoglobin of erythrocytes and is carried by the blood throughout the body. Ventilation of the lungs occurs through inhalation and exhalation. Inhalation occurs due to the contraction of the intercostal muscles and the diaphragm, thereby increasing the volume of the chest cavity. With relaxation of the intercostal muscles and the diaphragm, the volume of the chest cavity and the volume of the lungs decrease - exhalation occurs.

Circulatory system mammals similar to circulatory system birds. The heart is four-chambered: two atria and two ventricles. On the left side of the heart is arterial blood, in the right - venous (Fig. 197).

Rice. 197. Scheme of the structure of the circulatory system of a mammal: 1 - heart; 2 - left aortic arch; 3 - carotid artery; 4 - dorsal aorta; 5 - jugular vein; 6- pulmonary artery; 7 - pulmonary vein; 8 - back vena cava; 9 - capillary network of internal organs

Purely arterial blood from the left ventricle moves through the systemic circulation to all organs and tissues of the body. True, unlike birds, mammals retained not the right, but the left aortic arch. Venous blood from the right ventricle through the vessels of the pulmonary circulation is sent to the lungs, where it is enriched with oxygen. The rapid movement of purely arterial and purely venous blood (especially towards the head along carotid arteries and from the brain through the jugular veins) provides the body with oxygen and quickly removes harmful products vital activity. This provides a fast metabolism, high and constant body temperature of mammals.

excretory system presented by the kidneys. They are located in the pelvic region and are compact bodies. In the kidneys, the products of protein metabolism are filtered out of the blood: urea and some salts along with water. Through the ureters, urine flows into the bladder and through the urethra is removed to the outside (Fig. 198).

Rice. 198. The structure of the excretory and reproductive systems of mammals - male (A) and female (B): 1 - kidneys; 2 - ureters; 3 - bladder; 4 - testes; 5 - ovary; b - seed ducts; 7 - oviducts; 8 - uterus; 9 - urethra

The structure and activity of the systems of internal organs of mammals testifies to their more perfect, progressive development: intensive metabolism, constant and high body temperature. The comparison of mammals with birds shows their independent and parallel historical development.

Lesson learned exercises

1. What are the similarities and differences in the structure of the integument of the body of mammals and reptiles?
2. List the main features of the structure of the skeleton of the head, torso, limbs associated with the terrestrial lifestyle, with the type of nutrition.
3. Explain how the structure of the cerebral cortex of predators and primates differs from that of rodents.
4. On the example of rodents and ruminants, explain the characteristic features of the structure of the digestive system.
5. What complications have occurred in the structure and activity of the systems of internal organs of mammals in comparison with reptiles?

External and internal structure The rabbit is fundamentally similar to the organisms of other mammals. Although it has certain differences associated with belonging to the hare family. They have thick fur and large ears, the length of which can reach one third of the size of the entire body. Depending on belonging to a particular breed, the appearance of animals may vary slightly, but the structure of the internal organs corresponds general characteristics kind of rabbit.

Features of the anatomical structure and constitution

Many years of breeding work aimed at breeding meat, fur and decorative breeds made it possible to create animals that differ from each other in some features of the anatomical structure. In modern rabbit breeding, 4 main types of rabbit constitution are distinguished:

• animals of a rough constitution of the body with a disproportionately large head, a massive skeleton and well-developed muscles;
• standard rabbits with a strong body constitution, having a wide chest, a well-developed muscular system and a small, elongated or rounded head;
• delicate animals of decorative breeds with poorly developed muscles and fragile bones;
• rabbits of a raw constitution are large in size, but loose muscles, their hairline is not thick, and accumulates under the skin a large number of fat.

Depending on the type of body structure, animals are classified as meat, meat-fur or decorative breeds. The latter can have a body length from 20-25 cm to 1 m, and the color of their fur is distinguished by a wide variety of colors and shades.

Small animals with long ears

Rabbits of different breeds differ from each other in appearance. The same signs can be both positive and negative for various representatives of the hare family.

Males have a larger head than females, but it should always be in proportion to the rest of the body. The color of the shiny eyes varies from black to red and pink (in albinos).

Most rabbits have long and upright ears capable of reaching one third of the entire body length. But there are also lop-eared breeds.

The neck can be standard or shortened, but its muscles should easily support the massive head of even giant individuals. The structure of rabbits can be cylindrical (in chinchillas), traditionally stocky (Viennese blue) or rectangular (silver) shape. Animals of downy breeds outwardly resemble a ball.

A characteristic sign of a properly developing rabbit is a straight back and loin. Humpback is considered a defect, and such animals should not be allowed to reproduce offspring.

In females large breeds may be a massive dewlap. This is not a defect, but a sign of the normal state of the animal.

Muscular body and soft fur

The structure of the rump and rump can be round or wide (females are easier to rabbit), and a lopped or drooping rump is a serious defect and the first sign that a rabbit needs to be culled.

The legs must be strong and support the weight of the body. Any curvature and clubfoot are considered defects and may indicate the development of rickets.

The belly of healthy rabbits is large and elastic. The presence of any hardening in it indicates health problems and requires immediate treatment. The rabbit must have at least four pairs of well-developed mammary glands. The skin of a healthy animal is elastic. In males, it is somewhat coarser than in females.

Rabbit fur is soft and silky. It has a different density and length, but it always shines in healthy animals. Ushastiki have a uniform one-color (white giant, New Zealand rabbits), or a multi-colored fur color (for Russian ermines). In representatives of some breeds (chinchillas), coat color may be zonal.

Females bearing offspring are somewhat larger than males, although external structure their bodies are more tender. Animals quickly reach sexual maturity and can bring from 24 to 60 cubs per year.

Musculoskeletal system of the rabbit

The basis of the skeletal system of rabbits is a long vertebral column, to which, with the help of cartilage and connective tissue, the skull, chest bones with ribs, as well as the fore and hind limbs are attached.

There are 212 bones in the body of a rabbit. In babies, the weight of the bones can reach 15% of the total mass of the animal, and in an adult, this figure drops to 10%.

Specialists share the axial skeleton, which consists of the spine and cranium, and the peripheral skeleton, which includes the chest, pelvic bones, and limbs.

The skull of a rabbit differs little in structure from the skull of any other mammal. The spine is divided into cervical, thoracic, lumbar, sacral and caudal regions.

The mobility of the neck is achieved by 7 cervical vertebrae. Muscles are attached to the thoracic, lumbar and sacral bones, providing high mobility and jumping ability of these animals.

The anatomy of rabbits of meat breeds is coarser, and the powerful bones of the limbs allow you to hold a mass of up to 12-15 kg. Muscles are represented by striated muscles, and the walls of blood vessels are smooth muscle tissue, which ensures the permeability of blood and nutrients.

The internal organs of the rabbit are covered with a fatty layer that protects them from mechanical damage.

The structure of the cardiovascular system

Cardiac striated muscle pushes blood, directing it to all organs and tissues of the animal. The heart of a rabbit is a small muscular sac, consisting of two atria and two ventricles. With an average weight of 6-6.5 g, it is reduced from 110 to 160 times per minute.

Through the systemic circulation, arterial blood enters the organs and tissues of the animal. Poor blood returns through the veins to the heart. Through the pulmonary circulation, it is redirected to the lungs, where it is again enriched with oxygen, which is necessary for the normal functioning of the body.

The body of a medium-sized rabbit contains about 280 ml of blood, which consists of erythrocytes, leukocytes, and platelets.

The constant movement of blood ensures the maintenance of the temperature regime in the body of the animal. In winter, the standard figure is about 37 degrees Celsius, and in the heat it can rise to 40-41.

The bone marrow is responsible for the formation of blood, and the spleen destroys damaged or excess blood cells.

Features of the gastrointestinal tract

The digestive system of rabbits is represented by the jaw apparatus, esophagus, stomach and intestines, in which food is processed and broken down, as well as the absorption of nutrients.

Rabbits at birth have 16 teeth, which by the end of the third week are replaced by 28 adult teeth.

Teeth grow throughout life, so animals must constantly grind them, using hard food. Read more in the article "How many teeth do rabbits have".

Rabbits are herbivores, their stomach is quite voluminous and can hold up to 2000 cubic meters. see plant foods.

Fiber in the stomach is not broken down and enters the crushed form in the intestines.

The remains of undigested food and waste products are excreted from the body 9 hours after eating.

The respiratory system and its role in the life of a rabbit

The respiratory organs are represented by the nose, pharynx, trachea and lungs. The complex structure of the nasal cavity allows animals to cool the hot summer air and warm it in winter, thus protecting the lungs from burns and frostbite.

The respiratory rate in rabbits is very high. On average, he is able to take up to 282 breaths per minute, passing about 5000 cubic meters through the paired lungs. see air. In the alveoli, oxygen is absorbed by hemoglobin, which is part of the erythrocytes, and along with the blood is carried throughout the body.

Rabbits are very sensitive and can suffocate from ammonia fumes that accumulate in rarely cleaned cages. In the fresh air, animals grow very quickly. They have an excellent appetite, get sick a little and quickly gain industrial weight. At the same time, their skin acquires excellent production characteristics.

Other systems of internal organs

The excretory and urogenital systems of the rabbit are represented by the kidneys, ureters and urethra, as well as sweat and sebaceous glands protecting the body from hypothermia and excessive heating.

The kidneys filter the venous blood, clearing it of harmful substances. Violations of their work leads to a sharp deterioration in the health of the pet and his death.

The fluid that accumulates in the bladder, called urine, is excreted through the urethra into the external environment. It is saturated with urea and ammonia and must be removed from the cells in a timely manner.

The genital organs of males are represented by paired testes, which begin to produce sperm already 3.5-4 months after birth. During one mating, the male can excrete up to 3.5 ml of it.

The rabbit has a uterus, a pair of ovaries, an oviduct, a vagina and a genital slit through which the processes of fertilization and birth are carried out.

Nervous system and endocrine glands

Like other mammals, rabbits have a well-developed brain and spinal cord, as well as a peripheral nervous system. The brain has several convolutions, and a large number gray matter makes these animals intelligent. Ushastiki quickly get used to the feeder and tray, recognize the owners and love to spend time in their arms.

Nerve endings permeate all organs of the body. This makes the rabbits sensitive to pain and allows them to react more quickly to danger. Of great importance in the life processes of animals are the endocrine glands that produce hormones and other biologically active substances.

Produces the hormone thyroxine thyroid responsible for normal growth and the development of young animals, as well as the passage of metabolic reactions in the body of rabbits. The pancreas controls the process of digestion of food, and the adrenal glands provide water and fat metabolism.

Without testicles and ovaries, reproduction of these animals is impossible, and the pituitary gland produces more than 10 different hormones that positively affect the nervous system and other life processes.

sense organs

Since rabbits in nature are the main food of predatory animals, sense organs are of particular importance for them, allowing them to respond in a timely manner to threats and hide in burrows.

The vision of these animals is complex. It is represented by a pair of eyes capable of detecting colors. Rabbits are farsighted, but they do not see very well at close range.

Rabbits see perfectly in the dark and have a 300-340 degree all-round view.

Thanks to the resonant large auricles Rabbits have very sensitive hearing. They are able to turn their ears in different directions, capturing high-frequency sounds, with the help of which they communicate with each other.

Lop-eared rabbit breeds have lost the ability to hear well and will not be able to survive on their own in natural conditions.

Rabbits have a good sense of smell and distinguish thousands of smells. In this they are helped by special hairs located in the nasal cavity.

Circulatory system

The circulatory system 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). Vessels of all three 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. At their expense, networks are formed (especially between capillaries), collectors, collaterals - lateral vessels that accompany the course of the main vessel.

Heart- the central organ of the cardiovascular system, which, like a motor, moves blood 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 in mammals is four-chambered, completely divided from the inside 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, by the nature of the circulating blood, 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 heart is to ensure a continuous flow of blood in the vessels. At the same time, 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 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 from the beginning.

The wall of the heart consists of three membranes (layers): endocardium, myocardium and epicardium. The endocardium is the inner shell of the heart, the myocardium is the heart muscle (it differs from skeletal muscle tissue by the presence of intercalated crossbars between the individual fibers), the epicardium is the outer serous membrane of the heart. 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 its functioning. The walls of the left ventricle are 2-3 times thicker than the right one.

The heart rate largely depends on both the condition of the animal and its age, physiological state and temperature. environment. 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. The pulse is determined by femoral artery or brachial artery for 0.5–1 min (four fingers are placed on the inner surface in the area of ​​the femoral canal or shoulder, and thumb- 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.

According to their functions and structure blood vessels divided into conductive and energizing. Conductive vessels are arteries (they conduct blood from the heart, the blood in them is scarlet, bright, as it is saturated with oxygen, they are located deeper in the body of the animal, under the veins); veins (bring blood to the heart, the blood in them is dark, because it is saturated with metabolic products from the organs, they are located closer to the surface of the body); feeding, 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 the metabolism between blood and tissues (links of the microcirculatory bed) and redistributing blood. Entering the organ, arteries repeatedly branch into arterioles, precapillaries, passing into capillaries, then into postcapillaries and venules. Venules, which are the last link in the microcirculatory bed, merge with each other and become larger, forming veins that carry blood out of the organ. Blood circulation takes place closed system, consisting of large and small circles.

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 carries out the transfer of oxygen from the lung alveoli to tissues (due to the respiratory pigment hemoglobin contained in red blood cells) and carbon dioxide from tissues to the respiratory organs (this is done by salts dissolved in plasma), as well as nutrients (glucose, amino acids, fatty acids, salts, etc.) to tissues, and the end products of metabolism (urea, uric acid, ammonia, creatine) from tissues to excretory organs, and also transports biologically active substances (hormones, mediators, electrolytes, metabolic products - metabolites). The 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 of water-salt metabolism and acid-base balance in the body, in maintaining a constant body temperature, and also protects the body from the effects of bacteria, viruses, toxins and foreign proteins. The volume of circulating blood in the body of a rabbit is 5–6.7% of the total live weight and depends on the age, type and breed of the animal.

Blood consists of two important components - formed elements and plasma. The share of formed elements accounts for approximately 30-40% of the volume of all blood, plasma - 70%. The formed elements include erythrocytes, leukocytes and platelets (Table 5).

Table 5

Composition of the blood of a healthy rabbit

Hematocrit - 34-44%

Erythrocytes - 5-7 million / mm 3

Hemoglobin - 10-15 g / 100 ml

Leukocytes - 6-13 thousand / mm 3

Lymphocytes - 60%

Platelets - 125-250 thousand / μl

The amount of blood - 55–63 ml / kg of live weight

Erythrocytes, or red blood cells, carry oxygen from the lungs to organs and tissues, the immunological characteristics of the blood depend on them, due to the combination of erythrocyte antigens, that is, the blood type. 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 is the leukocyte form of blood. All types of leukocytes are involved in the protective reactions of the body. Platelets, or platelets, are involved in the process of blood clotting.

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.

The circulatory system The circulatory system 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

The Lymphatic System The lymphatic system is a specialized part of the cardiovascular system. It consists of lymph, lymphatic vessels and lymph nodes. It performs two main functions: drainage and protective. Lymph is a transparent yellowish

Digestive system The digestive system of a dog consists of the oral cavity, pharynx, esophagus, stomach, small and large intestines, liver and pancreas. The oral cavity is formed by the upper and lower lips, cheeks, gums, teeth, soft and hard palate,

Respiratory system The respiratory system performs the function of gas exchange: it ensures the entry of oxygen into the body of the animal and the removal of carbon dioxide from it. The breathing process occurs due to the contraction of the diaphragm. The respiratory system includes

Urinary system The urinary system performs the functions of cleansing the body of processed waste products and removing excess water. It is formed by the kidneys, ureters, bladder and urethra. The kidneys are

Reproductive system Like many other mammals, a dog distinguishes between external and internal genital organs. The genital organs of a female (female) are represented by the vulva, vagina, uterus, 2 oviducts and ovaries (steam gland). External genitalia - vulva and vagina -

The circulatory system The circulatory system includes: the heart - the central organ that promotes the movement of blood through the vessels, the blood vessels - the arteries that distribute blood from the heart to the organs, the veins that return blood to the heart, and the blood capillaries through

Circulatory system The circulatory system consists of the heart, blood vessels, blood and hematopoietic organs. The dog's heart is located in the chest cavity. Like all mammals, it is four-chambered, consists of two atria and two ventricles and

Nervous system caucasian shepherd dog must have a strong nervous system. Only in this case, she will be able to perform any work entrusted to her. A strong nervous system determines the performance of the Caucasian Shepherd Dog, its activity and endurance. As a rule, at

The circulatory system The circulatory system includes the heart - the central organ that promotes the movement of blood through the vessels and blood vessels - the arteries that distribute blood from the heart to the organs, the veins that return blood to the heart, and the blood capillaries through

The Lymphatic System The lymphatic system is a specialized part of the cardiovascular system. It consists of lymph, lymphatic vessels and lymph nodes. It performs two main functions - drainage and protective. Lymph is a transparent yellowish

The 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 distribute blood from the heart to organs, veins that return blood to the heart, and blood capillaries through

The circulatory system The circulatory system includes: the heart - the central organ that promotes the movement of blood through the vessels, and the blood vessels - the arteries that carry blood from the heart to the organs, the veins that return blood to the heart and the blood capillaries through the walls

Respiratory organs and circulatory system The respiratory system in canaries is very complex. From the neck to the intestines, there are air sacs connected to the lungs, as well as to the cavities of hollow and spongy bones. The lungs are designed so that air passes through them 2 times - the first

Circulatory system The circulatory system consists of the heart, blood vessels and hematopoietic organs. The dog's heart is located in the chest cavity. Like all mammals, it is 4-chamber, consists of 2 atria and 2 ventricles and is connected to large