The internal structure of geese. External and internal structure of birds. Internal organs of birds. Scalding or wet method

Rice. 251. Chestbone of a goose:

a-clavicle (fork); b, b"- scapula; c-coracoid; d-sternum; th"- crest of the sternum; e- sternum notch; /-segments of sternal ribs; d-bundle.

Rice. 252. Pelvis and lumbar

sacral spine

chicken from the ventral side.

a- lumbosacral spine; b- the last edge; with-ilium; d-ischium; e-pubic bone; /-locked hole.

(Fig. 250- 20; 251-d"). Its value is determined by the degree of massiveness of the pectoral muscles, due to which the flight is mainly carried out; running birds (ostriches) lack a crest. The posterior edge of the sternum has a paired notch of various sizes - incisura sterni. At ducks it is oval in shape and small, and geese(Fig. 251- e) behind completely closes in the hole. At chickens the notch is very deep, triangular in shape, so that its lateral border forms a long lateral process (Fig. 250- 21). Next to him, chickens still have a pronounced costal process (23). The lateral edges of the sternum have pits for articulation with the sternal parts of the ribs, and at the cranial edge on the right and left is located along the articular surface (sulcus articularis) for articulation with the coracoid bone of the shoulder girdle.

The lumbosacral, or pelvic, section of the trunk contains 11 to 14 segments, which fuse shortly after their development into the os lumbosacrale. The first of them, as indicated, merges with the last thoracic vertebra, and the posterior one with a number (from 3 to 7) of the caudal vertebrae. In addition, part of this monolithic vertebral mass connects so completely with the ilium of the pelvic girdle that the segments are visible only from the ventral side due to the presence of rudiments in front and behind

SYSTEM OF ORGANS OF VOLUNTARY MOTION

transverse costal processes of the vertebrae (Fig. 252). The exits from the spinal canal - foramina intervertebralia - open. between all adjacent vertebrae.

The tail section consists of five vertebrae in chickens, seven distinct and mobile vertebrae in ducks and geese (Fig. 250- 15). In addition, at the very end, a special tail bone, called the coccyx, or pygostyle m, -pygostyl (.76 "), is movably attached to them, on which tail feathers are strengthened.

Head skeleton

The head skeleton of birds is relatively small, with a specific structure of the facial region. Individual bones soon after the chick hatches from the egg fuse together so that their seams are completely smoothed out. Only ducks and geese have two fontanelles in the occipital region for some time.

The brain part of the skull consists of early fused bones: occipital, sphenoid, parietal, temporal, frontal, lacrimal and ethmoid.

The occipital bone, os occipitale, is characterized by the presence of only one occipital tubercle in the form of a head for articulation with the atlas (reptiles also have this form of connection).

Sphenoid soldering -os sphenoidale - the base of the skull has only temporal wings.

In the temporal bone and os temporale-stony bone and scales are fused, and a zygomatic process of various lengths and thickness departs from the scales. In chickens, it has at its base an articular surface for articulation with a quadrate bone.

The parietal bones and ossa parietalia are rather wide and lie between the scales, the occipital bone and the frontal bones, and the interparietal bone is absent.

The frontal bones - ossa frontalia - are developed significantly and take part in the formation of the orbit.

The right and left orbits in birds are relatively wide, deep and separated from each other by a thin interorbital bone plate.

The ethmoid bone, os ethmoid ale, consists only of the ethmoid and perpendicular plates, and the labyrinth is not developed.

The lacrimal bones - ossa lacrimalia - limit the orbits from the oral margin.

The facial section of the skull of birds is more complicated, but its volume in most of them is small compared to the brain section. Its lightness is mainly due to the absence of teeth, which is very typical for all modern birds (the first birds possessed them). The second feature is that the entire upper part of the facial section lying in front is merged into one whole formation, mobile in relation to the brain section, creating the skeleton of the upper beak of birds. The facial part of the skull includes: incisor and nasal bones, dorsal jaw, vomer, palatine, pterygoid, quadratojugal and quadrate bones, as well as a complex ventral jaw.

Incisal bones and-ossa incisiva (Fig. 250- 1) - even before hatching, the chicks merge into one, the most massive bone of the upper beak. She gives off paired, backward-directed processes: the upper nasal, or frontal, and lower jaw. The processes frame the anterior edge of the nostril, with the superior processes reaching the frontal bone.

The dorsal jaws and maxillae are poorly developed, toothless and also participate in the formation of the skeleton of the beak. They are located

SKELETON 915

along the lateral edges of the beak, behind the jaw process of the incisor bone and have lamellar palatine processes that form the hard palate. In chickens, these processes are very weak and do not reach the middle sagittal plane.

Nasal bones and -ossa nasalia (3) -located in the upper beak on the right and left between the frontal processes of the incisor bones and the dorsal jaw. They limit the nasal opening from behind.

The nasal cavities are separated from each other by a nasal septum, supplemented ventrally by a vomer. Oral area of ​​the nose

Rice. 253. Scheme of the skeleton of the head of a goose. BUT- with a closed beak, AT- with an open beak.

a, a ""- skeleton of the mandible; b, b"-mandible skeleton; 1 -palatine

bone; 2-zygomatic arch; 3 - pterygoid bone; 4 -square

bone: 5 -process.

the howling of the septum is bone or cartilaginous, and the aboral passes into the connective tissue membrane. The posterior, directed to the frontal bone, sections of the nasal bones and processes of the incisor bone are very thin flexible plates, and the nasal septum in this area is connective tissue.

This structure allows the mandible to rise in relation to the medulla of the skull. This movement is carried out through a special transmission at the moment of lowering the ventral jaw (see below).

Palatine bones and-ossa palatina (Fig. 253- 1) -participate in the formation of the hard palate and limit the choanae separated by the vomer. They are movable and are connected in front by a joint with the dorsal jaws, and behind with the pterygoid bones. In general, the palatine bones are one of the links in the movable chain between the quadrate and the mandible.

Pterygoid bones and ossa pterygoidea {3) -quite large and serve as a continuation of the palatine bones back and to the sides, towards the square bones. With their anterior ends, lying closer to the midsagittal line, they are jointed not only with the posterior ends of the palatine bones, but also with the sphenoid bone.

voluntary movement system

Their posterolateral ends are also articulated by joints with square bones. Thus, between the skeleton of the beak and the square bones there is a chain of movable palatine and pterygoid bones.

Zygomatic arch -arcus zygomaticus (2) - connected by the anterior end to the dorsal jaw of the upper beak, and by the posterior end to the quadrate bone. The arc consists of two bone elements; of these, the anterior is called the zygomatic bone-os iugale, and the posterior quadrate-zygomatic bone-os quadra-toiugaie.

Square bones-ossa quadrata (4) -irregular, approximately quadrangular in shape, equipped with a number of processes. One serves as a lever on which a special muscle is fixed, and the remaining processes are articular. They articulate the square bone: ventrally with the jaw, dorsally with the temporal bone, and orally with the pterygoid and quadratojugal.

The ventral jaw of the mandibula was formed as a result of the fusion of six bones, which are also found in reptiles. The anterior, most developed, part of it is called the dentary-os dentale, and the posterior articular bone-os articulare. Between them lie: os complementare, os operculare, os angulare and os supraangu-lare. They all merge with each other. In the area of ​​the articular bone, the ventral jaw is connected by a joint to the quadrate bone. A slightly curved process protrudes behind the articulation from the jaw (5) to attach the muscle that opens the jaw. This shows how complex the jaw joint of birds is built (see the section on musculature for its mechanism of action).

Rice. 254. Hyoid bone.

a, a"- intralingual bone; b- the main site; c - keel (karina); d-branches of the hyoid bone.

Hyoid bone-os hyoideum (Fig. 254) - consists of a body and one pair of branches (horns). In the body, in turn, they distinguish the main part of the k-basihyoid (6), in front of which there is an intralingual bone-os endoglossum (a)- giving the basis to the tongue, and back - keel-carina (c), reaching the trachea. Long (two- or three-membered) branches depart from the main site, enveloping the skull, but not directly connected with it.

Skeleton of the thoracic limbs

The thoracic limb of birds is greatly changed in comparison with the limbs of the leg-shaped form of the ancestors of birds and was called the wing. It, like the leg-shaped limb, can be divided into the skeleton of the shoulder girdle and the skeleton of the free part of the wing.

The skeleton of the shoulder girdle of birds is more complete than that of mammals; it includes on each side the scapula, clavicle, and coracoid. All of them are firmly connected with each other and rest against the sternum through the coracoid. This design creates strength with the ability to make large and strong swings of the free part of the wing in the segmental plane during flight.

Scapula and scapula (Fig. 250- 27) - has the appearance of a slightly curved narrow plate, devoid of scapular cartilage. It is located obliquely backwards and slightly upward from the shoulder joint (almost along the vertebral ends of the ribs). Its humeral end, or articular angle, bears articular surfaces for articulation with the clavicle, coracoid, and humerus.

coracoid bone b-os coracoideum (18) - the most powerful in belt and is firmly connected by a tight joint with the sternum at its cranial end. It stands at an acute (almost right) angle to the scapula and from the shoulder joint is directed downward, backward and slightly medially to the sternum. The humeral end of the bone is connected to the scapula, the humerus and a tight joint with the clavicle.

Clavicle s-claviculae (17), - right and left, articulating at the shoulder joint with the scapula, go down and fuse with each other with their distal ends. In chickens, at the place of their confluence, there is a small process fastened to the sternum with a ligament, and in some birds these ends are fused with the sternum. Both collarbones together form a fork, or furcula.

Free wing skeleton. Two links of the main column of the limb are fully expressed, and the distal link is greatly changed and significantly reduced. exactly.

Humerus b-os humeri (33) -tubular type, strongly developed and has thickened ends. When the wing is at rest, it is located on the chest and is directed from the shoulder joint back to the pelvis. Its proximal (shoulder) end, in the form of a slightly convex oval head, connects with a cavity formed jointly by the scapula and coracoid. This end is significantly thickened due to the presence of a lateral (or small) end on it. and the medial (or greater) tubercles. Here, on the medial side, there is an opening - foramen pneumaticum - leading to the air cavity, bones. The distal end is slightly thickened and bears a semicircular articular surface for the ulna on the volar side, and an ovoid surface for the radius on the dorsal side.

Bones of the forearm i-ossa antebrachii. In the link of the forearm is strong. it has a developed ulna - ulna (35). It is slightly curved and equipped with a weakly expressed olecranon. Nearly straight, thinner radius-radius (34) - lies dorso-medially. A fairly wide interosseous space, the spatium interosseum, remains between the two bones. The forearm at rest of the wing is located almost parallel to the shoulder, that is, it is directed forward from the elbow joint.

Distal wing link corresponding to the front paw (hand) of the leg-shaped limbs, is very strongly modified and adapted to the one-sided function of flight. This change was expressed in the reduction of individual members in all sections of this link. The link itself, when the wing is at rest, lies at an acute angle to the forearm and the distal end is directed backward and slightly lowered down.

3 a p i s t e-carpus (36, 37) -preserved only in the form of carpal radius-os radiale-and carpal ulna-os ulnare-bones; the carpal intermediate is fused to the carpal radius, and the accessory is fused to the carpal ulna. The distal row of carpal bones is completely fused with the metacarpal coetae.

The metacarpometacarpus (56) is reduced to three segments (2,3, 4th), and even those are fused into one formation, to which the distal row of the carpus is also attached. Of these, the most noticeable are the 3rd and 4th metacarpal bones, fastened at their ends and having an interosseous space between them. The second small metacarpal bone is completely fused with the proximal end of the neighboring one.

Finger Skeleton (39, 40, 41) also greatly reduced. The 3rd finger with two phalanges is most clearly preserved; The 2nd and 4th fingers are small and, as a rule, consist of one phalanx (for the connection between the elbow and carpal joints, see the section on musculature).

918 system of organs of arbitrary movement

Biological features of the bird

Most character traits birds that distinguish them from other vertebrates is the ability to fly and the intensity of the course of life processes.

The ability to fly was reflected in the entire organization of birds. In flight, the bird makes a huge number of movements, which is accompanied by a large expenditure of energy and an intensive metabolism, which also determines a high constant body temperature (average 42 ° C), which requires increased work from the heart. The number of heartbeats in chickens is 128-340 beats per minute.

The lungs of birds are relatively small, despite this enrichment of the body with oxygen is quite intensive due to the action of the air sac system, their volume is several times greater than the volume of the lungs. Air bags play important role in thermoregulation, moisture evaporates from their surface through the respiratory tract, which prevents the possibility of overheating of the body. Since birds do not have sweat glands and evaporation of moisture occurs through the respiratory organs, therefore chickens always open their mouths at high temperatures. Food in birds is crushed in the stomach, which has powerful muscles and is lined from the inside with a dense film - the cuticle.

Grinding of food is enhanced by gravel and coarse sand eaten by birds.

Birds have good eyesight and excellent hearing. The field of view of the chicken is 300 o.
Poultry has completely or partially lost the ability to fly. She has greatly increased her productivity.
There is no seasonal oviposition.

Skeleton

In the course of evolution, birds formed a light and very strong skeleton.

The skeleton of a chicken consists of bones and cartilage connected by ligaments and is the solid foundation of the body.

The bones of the chicken skeleton also serve as a place for the accumulation of mineral salts necessary for the life of the organism and, in particular, for the formation of eggs. At the same time, minerals are constantly consumed and at the same time replenished due to substances received by chickens with food. Therefore, to ensure a good and long-term egg laying of chickens, it is necessary that before the start of mass wear in pullets, the ossification of the skeleton is completely completed and the necessary reserves of mineral substances accumulate inside the body. Without this, the chicken will not be able to have high productivity for a long time.

Connecting with each other, all the bones of the chicken are combined into a single skeleton. The bones of the skeleton serve as levers when the bird moves, they protect the brain and spinal cord, heart and other internal organs from harmful mechanical effects and damage. The purpose of the individual bones of the skeleton is different, and therefore their structure and shape are not the same. From the outside, the bone is covered with a special shell, the so-called periosteum. It contains blood vessels and nerves. Here are special cells - bone-forming. In a young organism, due to the multiplication of these cells from the side of the periosteum, the bones grow in thickness.

The skeleton of a bird is divided into axial and peripheral. The axial skeleton includes the bones of the head, trunk and tail, and the peripheral skeleton includes the bones of the limbs.

The head skeleton of chickens is small. It consists of brain and facial sections. The medulla forms the cranium. It contains the brain. The front section is more complicated. Its upper part also consists of fused bones and forms the upper beak, which is fixedly connected to the cranium. The lower part of the face is the jaw. It has a movable connection with the cranium.

The skeleton of the body is divided into cervical, thoracic and lumbosacral (pelvic) sections. The cervical region of chickens is the largest. It has 13-14 vertebrae connected movably. Due to this, the neck of chickens is long and very mobile, which is of great importance for obtaining food, cleaning and lubricating feathers. The thoracic region is the chest, consisting of the vertebrae, ribs attached to them and the sternum. Chickens have seven thoracic vertebrae and, accordingly, the same number of pairs of ribs.

The thoracic vertebrae from the second to the fifth are fused, and the last (seventh) has grown to the lumbosacral region. Five pairs of ribs are fused with the sternum and due to this they form a rather extensive chest cavity, protected from mechanical influences, where the most vital organs are located - the lungs and the heart. The ribs are interconnected by intercostal hook-shaped processes, which significantly strengthens the chest. The sternum in chickens has a highly developed crest, or keel. Powerful pectoral muscles are attached to it, setting the wings in motion. A lack of minerals in the diet of chickens, especially calcium, as well as vitamin D, causes thinning or curvature of the sternum.

There are 11-14 vertebrae in the lumbosacral region of chickens, but it is not easy to distinguish between them. Even at a young age, the birds fuse tightly not only with each other, but also with the last thoracic and first caudal vertebrae, forming, as it were, one lumbosacral bone. This bone is also tightly connected to the bones of the pelvis. There are only 5-6 vertebrae in the tail section of chickens. They have loose connections. The last tail vertebra is the largest and has a special shape. It is called the coccyx (pygostyle).

The wing skeleton consists of the bones of the shoulder girdle and the bones of the wing itself. The shoulder girdle includes the scapula, clavicle and caracoid bone. They serve to movably connect the wing to the skeleton. In the wing itself are the following bones: the humerus, two bones of the forearm - a thicker ulna and a thinner radius, two carpal bones, a metacarpal bone and three poorly developed finger bones.

The pelvis consists of paired lamellar bones: ilium, ischium and pubis. The iliac bones of the pelvis are fixedly connected to the sacrum. Unlike mammals in birds, the pubic bones are not interconnected. In laying hens, they seem to soften, become elastic and diverge from each other for a considerable distance. By the magnitude of this distance, one can judge whether the chicken is rushing or not. The more intense the oviposition of the chicken and the higher the weight of the eggs, the greater the distance between these bones. The difference between the skeleton of a chicken and a rooster is that the hens have a medullary bone, it is involved in the formation of the eggshell.

The skeleton of the pelvic limb consists of the femur, tibia, two metatarsal bones and four fingers. Of these, the posterior toe has two segments, the inner toe has three, the middle toe has four, and the outer toe has five. The end of each last segment has a claw. Mostly chickens have 4 fingers, however, there are breeds that are characterized by the presence of a fifth finger. The femurs of the legs are connected by movable joints to the pelvis.

Digestive system

The digestive system of chicken has its own characteristics. The digestive organs include the beak, oral cavity, pharynx, esophagus, goiter, glandular and muscular stomachs, intestines and cloaca. The beak and oral cavity are designed exclusively for mastering the food, as well as its transmission to the esophagus and further to the stomach. The chicken can swallow food in any position of the head, even if it is lowered down. This is ensured by the horny cloves on the tongue and palate of the chicken. But she swallows water only with her head up. It is very important to know this, since when keeping chickens in cages and transporting them in boxes, the latter must necessarily have a certain height and design that allows chickens to raise their heads above the drinker to a height sufficient to swallow water.

From the mouth, food passes through the pharynx into the esophagus. As a result of the wave-like contraction of the muscles of its walls, the feed masses, bypassing the goiter (elastic expansion of the esophagus), pass directly into the stomach. If the stomach is already full, then the food enters the crop, and then into the stomach as it is freed from the contents. The transition of food from the crop to the stomach is also due to the contraction of the muscles of the walls of the crop. When chickens are fed loose or pelleted compound feed, when it is in front of them throughout the day, their crop may constantly be empty or poorly filled, but this does not mean that the chickens do not eat enough feed. Since they peck it constantly, but little by little, the food, bypassing the goiter, enters directly into the stomach.

The absence of teeth in chickens is compensated by the presence of two stomachs (glandular and muscular). The esophagus is a long tube that leads from the mouth to the first stomach. The walls of the esophagus do not secrete any digestive juices; it is intended solely for transporting food to the stomach, and also quite often for its temporary storage.

Chickens swallow unchewed food, and its processing begins directly in the stomach. From the esophagus, food enters the glandular stomach. Its walls secrete strong acid and certain enzymes in abundance, which start the process of digestion of food, which soon passes into the second stomach, which is a cavity formed by extremely strong and durable muscular walls. Working on the principle of millstones, the walls of the muscular stomach, contracting vigorously, grind and grind food, preparing it for further digestion. The process of grinding food is facilitated by the presence of gastroliths - small pebbles or grains of sand that birds swallow specifically for this purpose.

The midgut, or small intestine, consists of the duodenum, jejunum, and ileum. In its wall lie parietal - intestinal - glands. The parietal glands are the liver and pancreas. Birds do not have duodenal glands. In the intestines there are long villi, and its mucous membrane is collected in folds, increasing the path of food through the intestines.

The duodenum emerges from the anterior portion of the muscular part of the stomach and goes to the pelvis, and then returns, forming a loop of two knees. This loop contains the pancreas.

The jejunum and ileum are suspended on a thin mesentery, in contact with each other and forming spiral curls. Ileum - opens into the hindgut at the border of the caecum with the rectum.

The liver is quite large, divided into two lobes and occupies a significant part of the ventral half of the abdominal cavity. The gallbladder is located on the right lobe of the liver.

Pancreas - located in the loop of the duodenum, has three lobes and three ducts in chickens.

The hindgut, or large intestine, does not have a colon in birds. Chickens have two blind guts. Their apices are turned cranially, and they are delimited from the ileum by a circular fold. The rectum passes into the cloaca, which is divided by two transverse folds into three sections: anterior, middle and posterior. The rectum opens into the anterior section, and the ureters, vas deferens (in males) and oviducts (in females) into the middle section. The posterior section of the cloaca ends with an anus, through which undigested food remains mixed with urine, and in females, eggs are also thrown out. The sperm of males also passes through this section during mating. On its dorsal wall, young birds have a protrusion - a fibrous (Fabrician) bag, which is reduced in adult birds.

Chicken stomach outside

Cutaway chicken stomach

The duration of the feed in the digestive tract of the chicken depends on many conditions, and above all on its preparation for feeding. The longest time in the digestive organs is whole grains and the least - mixed feed with a low fiber content. The time of passage of feed through the digestive organs of chickens also depends on their physiological state, on the intensity of the body's work. So, in young chickens, grain feed passes through the intestines in about 4 hours, and in non-laying adult chickens - in 8 hours, in laying, but low-yielding chickens - in 3 hours, and in highly productive chickens in just 2. These features must be taken into account when organizing bird feeding. That is why it is advisable for highly productive chickens to feed compound feed without restriction during the day. For the same reason, loose or granular compound feed, balanced in terms of all nutrients, is considered to be the best feed, for the digestion of which the chicken spends much less time and energy.

excretory system

With the help of the digestive organs, the chicken provides itself with nutrients for life support, body growth and egg formation. But in the process of constant metabolism occurring in the body, decay products are formed - chemicals harmful to the body, which are the result of the activity of cells, various tissues and organs. These substances must be removed from the body. This task perform the so-called excretory organs, which include the kidneys and ureters (urinary system), the bird does not have a bladder. Chickens have fairly large kidneys, they are located on both sides of the lumbar vertebrae. Inside them there are so-called renal glomeruli, shrouded in a dense network of the thinnest blood vessels - capillaries. Here, passing through the capillaries, the blood gives off excess fluid and substances harmful to the body, which are then released into the urinary tubules of the kidneys, forming urine.

Urine does not accumulate in the excretory organs, but is excreted from the cloaca, first coming from the kidneys to the ureters, then through the urinary tubules it is excreted into the cloaca. The excretion product is uric acid (up to 80% of the total urine nitrogen), which precipitates into solution in the form of crystals, forming a white mushy mass. In addition to the kidneys, harmful substances are excreted from the blood into the stomach and intestines, from where they are then thrown out with droppings. An important role in this is played by the liver, which neutralizes toxic substances entering the bloodstream from the intestines.

reproductive system

Males have two testicles located inside the body. The spermatozoa travel down the vas deferens into the cloaca and out of the body. Fertilization occurs when, during mating, the openings of the cloaca of the male and female come into contact. Males do not have an organ that penetrates the body of the female. In females, only the left ovary and oviduct usually function. The eggs travel down the reproductive tract from the ovary. The sperm travels along this path and fertilizes the egg at the very beginning of the process. Sometimes sperm cells can remain viable in the body of the female for up to three weeks after mating.

The time of the laying of the first egg by the young hen is considered the period of its puberty. It may come earlier or later, depending on the breed, as well as the individual characteristics of this chicken. In hens of egg breeds, puberty is usually observed at the age of about five months, and in hens of meat and egg breeds, about a month later. The period of puberty is greatly influenced by the conditions of feeding and keeping the bird.

With abundant feeding and a long daylight hours - more than 14 hours a day, chickens of egg breeds can be laid at the age of about 130 days, without having completed their growth and general physiological development. As a result, such chickens later become poor laying hens. They lay smaller eggs and drop egg production fairly quickly. Therefore, it is not recommended to artificially induce early puberty in chickens. It should come only after the young chicken has basically completed its growth, has fully developed, and its bones and organs have accumulated sufficient reserves of minerals, nutrients and vitamins.

At the beginning of laying, hens lay smaller eggs, then their weight gradually increases and reaches a normal value by 10-12 months of age. Therefore, to characterize chickens, the weight of eggs is determined at the age of one. Chickens lay the most eggs in their first year of life. In the second year (after molting), their egg production decreases by about 12-15%, and sometimes more.

Therefore, in commercial farms, chickens are kept only for a year or a little more - 13-15 months. The productive period of hens begins at 5 months of age, usually they are kept for eggs until 17-18 months, and sometimes 19-22 months of age. Egg-laying may stop prematurely if the hen begins to show the instinct of incubation - to cackle. But in hens of egg breeds, especially in leghorns, thanks to the long selection work carried out with them, this instinct has almost disappeared.

Usually chickens lay eggs intermittently. For example, a chicken is laid for 3-5 days, and then one or two days is not laid. The period of continuous laying of eggs (for several days in a row) is called a cycle. If 4-5 or more eggs are obtained during the cycle, then the cyclicity is considered good. Record-breaking hens during the period of the highest egg laying give up to 25 or more eggs per cycle. Chickens rush mainly in the morning or in the first half of the day. But some chickens can lay eggs at a later time of the day.

The reproductive system of the chicken

The reproductive system of the rooster

Nervous system

In birds, the relationship between the structure of the brain and the sense organs and their functions is clearly traced. The relatively insignificant role of smell in the life of birds is directly dependent on the small size of the olfactory lobes of the brain. The perfection of the organs of vision is due to the increased size of the visual tubercles of the well-developed midbrain.

leading role in all life processes any organism plays the nervous system. The nervous system communicates the body with the environment. All irritations coming from the outside are perceived by it through the senses. In response to these irritations, the functions of various organs change, the body adapts to environment. Sufficiently strong irritation in any part of the nervous system usually causes numerous reflexes that determine the reaction of the organism as a whole.

A reflex is a response of the body to irritation of nerve receptors (endings) located both on the surface of the body and inside it, carried out through the central nervous system. Reflexes are divided into conditional and unconditional. Acquired reflexes are called conditioned, they can occur throughout the life of a bird. Unconditioned reflexes are those that are innate and are inherited. The unconditioned reflexes include the sexual reflex, the defensive reflex, and many others. Conditioned reflexes are strictly individual and unstable, i.e., they can disappear without a systematic stimulus and reappear.

Sometimes, under the influence of extreme stimuli, a state of general tension of the body, called stress, can occur. Stress can have both positive and negative effects on the bird's body, up to its complete disorganization.

Circulatory system

Blood plays an important role in the life of the body. It, like lymph, delivers oxygen and nutrients to cells and tissues, carrying away decay products from them. Blood contributes to the regulation of body temperature, maintaining a certain chemical composition. The secrets of the endocrine glands, which regulate all processes in the body, are carried with the blood. Special substances (immune bodies) accumulate in the blood, which provide the body's immunity (immunity) to infectious diseases.

The total amount of blood in chickens is 8-9% of body weight. But at slaughter, only about half of this amount comes out, and the rest of the blood is retained in the tissues.

The heart of a bird works like a pump, pumping blood throughout the body and supplying its cells with oxygen. The heart of birds resembles the heart of mammals, although it is asymmetrical: its left half is more developed than the right, because it does more work. Birds' hearts beat faster than mammals of approximately the same size.

The average temperature of birds is 42 ° C. With all the undoubted advantages that their warm-bloodedness provides to birds, which allows them to overcome any vicissitudes of the climate, it should be noted that it is very expensive. After all, the warm body of a bird continuously cools down, and the faster, the higher the difference between the physiologically best tissue temperature for birds and the external temperature surrounding them. This difference must be constantly compensated by spending additional energy on continuous heating of the body.

Respiratory system

According to the structure of the respiratory system, birds differ from all other vertebrates. Light birds resemble a sponge, completely penetrated by numerous thin branching canals - parabronchi. Many special thin-walled cavities are connected to the lungs of birds - air sacs that penetrate literally into all corners of the bird's body and exceed the lungs by 3-4 times in total volume. Gas exchange does not occur in air sacs; they are intended solely for the storage and redistribution of air in the respiratory system of the bird.

It is the presence of these volumetric reservoirs that provides the main feature of bird respiration - the continuous flow of air through the parabronchi rich in blood vessels, where the blood is enriched with oxygen and releases carbon dioxide. This eliminates the inevitable pause in gas exchange that occurs immediately after exhalation. In a bird, the movement of air through the parabronchi is continuous and always in the same direction due to its independent inflow not only from the outside through the trachea, but also from the inside from different air sacs, the rhythmic emptying and filling of which is coordinated by complex nervous mechanisms and is carried out largely independently. from the rhythm of inhalation and exhalation. Such a breathing system ensures almost continuous saturation of the blood with oxygen and its uninterrupted flow to the tissues. The lungs of chickens practically do not change size and do not have the same ability to stretch as the lungs of mammals.

1. Anatomy of domestic animals / A.I. Akayevsky, Yu.F. Yudichev, N.V. Mikhailov, I.V. Khrustalev. – M.: Kolos, 1984. 543 p. (Textbooks and textbooks for higher agricultural educational institutions).

2. Vrakin V.F., Sidorova M.V. Morphology of farm animals; Anatomy with the basics of cytology, embryology and histology. – M.: Agropromizdat, 1991. – 528 p. (Textbooks and teaching aids for students of higher educational institutions).

3. Khrustaleva I.V., Mikhailov N.V., Shneiberg Ya.I. etc. Anatomy of pets /Under the total. Ed. I.V. Khrustaleva. M.: Kolos, 1994. S. 87-115.

Ministry Agriculture Russian Federation

FGOU VPO Tyumen State Agricultural Academy

Department of Anatomy and Physiology

bird anatomy

Toolkit

To laboratory and practical classes

for students of the specialty "Veterinary"

Tyumen 2011

The methodical manual was compiled by Ph.D. vet. Sciences, Associate Professor of the Department of Anatomy and Physiology of the TGSCA Veremeeva S.A.

The methodological manual was reviewed and approved at a meeting of the Department of Anatomy and Physiology of the TGSCA, protocol No. ____ dated _________ 20__.

Reviewer: Cand. biol. Sci., Associate Professor, Department of Anatomy and Physiology, TGSCA Barabanshchikova G.I.

Introduction. Features of the anatomical structure of birds…………………….3

1. Skeleton …………………………………………………………………….…..4

2. Muscles…………………………………………………………………….…8

3. Skin and its derivatives………………………………………….10

4. The apparatus of digestion………………………………………………………..11

5. Breathing apparatus…………………………………………………………………….13

6. Devices for urinary excretion and reproduction………………………………14

7. Cardiovascular system……………………………………………..…16

8. Glands of internal secretion………………………………………………..16

9. Nervous system and sense organs………………………………………………...16

Literature……………………………………………………………………...18

Introduction

Features of the anatomical structure of birds

The class of birds is divided into keeled and keeled. Poultry - keeled belong to two orders: chickens (chickens, turkeys, guinea fowls) and anseriformes (geese, ducks). Birds, in connection with their adaptability to flight, have a number of specific features in the structure of the body. In their development, they are closer to reptiles. Birds, like reptiles, do not have skin glands, strongly developed horny skin derivatives (feathers, scales, horny beak, claws), a typical lower zygomatic arch, compound sphenoid and mandibular bones, a single occipital condyle, a movable square bone, a complex sacrum, the presence of hook-shaped processes of the ribs, a metatarsal articulation on the pelvic limb, a similar structure of the kidney, etc. In birds, the following are better developed than in reptiles: the brain, organs of vision and hearing. They are distinguished by warm-bloodedness and other features associated with the peculiarities of their ecology.

A special mode of transportation - flight - left its mark on their entire organization. These features were dictated by the need to subordinate the form and structure of the body to the requirements of aerodynamics. The structural features of the system of organs of movement and the feather cover create a streamlined contour of the body, the thoracic limb has turned into a wing - a specialized aircraft. The bones are strong and light, often pneumatized, the head is lightened due to the absence of teeth. The cervical region is elongated and very mobile, together with the head acting as a front rudder, grasping limb and providing a circular view. The thoracolumbar region is short and inactive, the tail region is turned into the basis for tail feathers. The muscles are located extremely unevenly, providing mainly flight and walking. Internal organs located in such a way that the most massive (liver, stomach) lie near the center of gravity of the body. The intestine is short while maintaining high activity of secretory (large parietal glands) and absorption (villi in the large intestine) functions. Increased aeration due to the development of air sacs (double breathing), which contributes to the intensification of metabolic processes and the vital activity of birds. Relief of the excretory system - no bladder, reproduction - one ovary and oviduct, external development germ.

Skeleton

The lightness of the bird skeleton is created due to the greater mineralization of the compact, the porosity of the spongy substance, pneumatization, and early bone fusion. In females, before oviposition, spongy medullary bone accumulates in the bone marrow cavities of the tubular bones, which, with a sufficient Ca content in the diet, fills the entire bone cavity. During oviposition, the medullary bone is used to form the shell. With a lack of Ca, the compact becomes thinner, and the bones become brittle.

Scull(Fig. 1). The brain region of the skull is formed by unpaired occipital, sphenoid, ethmoid and paired temporal, parietal, and frontal bones. The seams between the bones of the skull are visible only in the first days after hatching. In adult birds, the boundaries between the bones are completely invisible. The shape of the bird's skull is greatly influenced by large eyes. Under their pressure, the orbital wings of the sphenoid bone fuse with each other and with the perpendicular plate of the ethmoid bone and become the interorbital septum. As a result, the brain region of the skull does not extend rostrally beyond the orbits. The occipital bone has one condyle, which greatly increases the mobility of the head.

The front section is more complicated. It is formed by paired incisive (intermaxillary), maxillary, nasal, lacrimal, palatine, zygomatic, pterygoid, square, mandibular and unpaired openers, hyoid bones. The incisive, maxillary and nasal bones form the bony skeleton of the upper beak - the upper beak. The nasal bones have the appearance of a thin springy plate, which joins (in goose joints) to the frontal and lacrimal bones and allows you to raise the upper beak. This movement takes place simultaneously with the lowering of the lower jaw - mandible due to the development of the lower zygomatic arches and the mobility of the quadrate bone. This bone of an irregular quadrangular shape forms four joints: with the temporal, pterygoid zygomatic and mandibular bones. The movable connection of the pterygoid, zygomatic, palatine, square, mandibular bones, with the combined work of several joints formed by them, form a good grasping mechanism of the bird's beak.

Skeleton of the spinal column(Fig. 1) . The cervical region in birds of different species has a different number of vertebrae: in chickens and turkeys - 13-14; ducks -14-15, geese - 17-18. The cervical vertebrae are mobile, have short spinous and well-developed transverse processes, rudiments of ribs in the form of costal processes. The complex relief of the heads and pits of the vertebrae provides not only flexion and extension, but also abduction to the sides, and limited rotation.

The thoracic region is short and inactive. It consists of 7 thoracic vertebrae in chickens, and 9 thoracic vertebrae in ducks, the same number of pairs of ribs and sternum. The vertebrae from the 2nd to the 5th have grown together into a single vertebral, or dorsal, bone. The 1st and 6th vertebrae are free. The 7th fused with the first lumbar.

Ribs in chickens consist of two bone parts - vertebral and sternal. 2-3 anterior and one posterior - sternal, the rest sternal. At the vertebral ends of the ribs there are hook-shaped processes that strengthen the chest wall. Between

Rice. 1. Chicken Skeleton:

1 - incisive (intermaxillary) bone; 2 - nostril; 3 - nasal, 4 - lacrimal, 5 - ethmoid, 6 - dental and 7 - square bones; 8 - tympanic cavity; 9 - atlas; 10 - coracoid bone; 11 - collarbone; 12 - scapula; 13 - dorsal bone; 14 - sternal and 15 - sternal ribs; 16 - hook-shaped process; 17 - body; 18 - costal lateral and 20 - middle processes of the sternum; 21 - her crest; 22 - humerus, 23 - humerus, 24 - ulna, 25 - carpal ulna and 26 - carpal radius; 27 - II finger; 28 - metacarpal bones; 29 - III finger; 30 - IV finger; 31 - ilium; 32 - sciatic foramen; 33 - tail vertebrae; 34 - pygostyle; 35 - ischium and 36 - pubic bone; 37- locked hole; 38 - femur; 39 - knee cup; 40 - fibula, 41 - tibia, 42 - metatarsal and 43 - metatarsal bones; 44 - I finger; 45 - II finger; 46 - III finger; 41 - IV finger.

vertebral and sternal parts of the rib, between the rib and the sternum - the joints.

The sternum is a flat bone, concave at the top. Her body is elongated in the caudal direction and on the ventral surface bears a crest - a keel. The body of the sternum in waterfowl is wide, the keel is not as high as in chickens. On the front edge of the body there are surfaces for articulation with the coracoid bone, on the sides there are 2 processes - lateral (thoracic) and posterior (abdominal), separated by deep notches. The most powerful muscles are attached to the sternum.

Lumbo-sacral and caudal regions. The last thoracic, lumbar, sacral, and first caudal vertebrae fuse into a single lumbosacral bone. It has 11-14, in goose - 16-17 bone segments. The pelvic bones grow to it from both sides, which is why the entire department is called the pelvic.

In the caudal region, there are 5 vertebrae in chickens, and 7 in ducks. The last 4-6 vertebrae fuse into a pygostyle, a flat triangular bone to which tail feathers are attached.

Thoracic skeleton(Fig. 1) . In connection with the adaptability to flight, the thoracic limb turned into a wing, the skeleton of which consists of a belt and a free limb.

The skeleton of the shoulder girdle of birds consists of three bones: the scapula, the clavicle and the coracoid bone. The scapula is a flat, long, narrow, saber-curved bone. Lies parallel to the spine at the vertebral ends of the ribs. The clavicle is a paired bone in the form of a thin rounded stick. The distal ends of both clavicles fuse, resulting in a fork.

The coracoid bone is the most powerful of the bones in the girdle. It is located almost at right angles to the scapula and parallel to the collarbone. The bone is pneumatized. The proximal end articulates with the scapula, clavicle and humerus, the distal end with the sternum.

The skeleton of the free thoracic limb consists of the bones of the shoulder, forearm and hand. The humerus is long, tubular, pneumatized, with a wide proximal epiphysis.

Of the bones of the forearm, the ulna is better developed - long, slightly curved. It is the main support of flight feathers. On the distal epiphysis there are two articular surfaces for articulation with the bones of the wrist and one with the radius. The radius is smaller than the ulna and looks like a cylindrical rod. There is a wide interosseous space between them.

The bones of the hand are greatly reduced. Of the carpal bones, only the carpal radius and carpal ulna have been preserved. Intermediate bone fused with the radial carpal, additional with the ulna carpal. The brushes of the distal row are fused with the bones of the metacarpus, which are also partially reduced and fused. II, III and IV metacarpals and bones of the distal row of the wrist fused into a single metacarpal-carpal bone or buckle. In the buckle, the largest part is formed by the III metacarpal bone. II bone looks like a small tubercle. Between the III and IV bones of the pastern is the interosseous space. Of the fingers, III is more developed, which consists of two phalanges, the II and IV fingers have one phalanx each. II finger is the bone base of the winglet.

Skeleton of the pelvic limb(Fig. 1). The skeleton of the pelvic girdle consists of the iliac, pubic and ischium bones, fused and the pelvic bone. All 3 bones take part in the formation of the articular cavity. The ilium lies along the lumbosacral bone, with which it fuses. Strongly inclined down. The cranial part of the bone is concave, here lie the gluteal muscles. The caudal part is convex, below it are the kidneys. The impoverished and ischial bones grow to the caudal edge of the ilium.

The ischium has the form of an elongated triangle. The pubic bone is in the form of a long thin curved stick running along the edge of the pelvic bone. The pubic and ischial bones do not fuse together. The basin has a wide entrance with soft walls - a device for laying eggs.

The skeleton of the free limb consists of the femur, lower leg and foot bones. The femur is long, tubular, pneumatized. Of the bones of the lower leg, the tibia is better developed, which also fuses with the bones of the tarsus and forms the tibial-tarsal or running bone - the longest and most powerful bone of the skeleton. The fibula is reduced, its distal end fuses with the tibia-tarsal bone. The bones of the foot, except for the toes, are fused. The tarsus doesn't exist. The proximal row of the tarsus became part of the tibio-tarsal bone, the distal and central rows merged with the bones of the metatarsus, and as a result of fusion of the II, III and IV metatarsal bones, they formed the metatarsal bone, or tarsus. At the distal end is a triple block for articulation with the bones of the fingers. At the distal end of this bone, an independent first metatarsal bone lies in the form of a pea. Roosters have a curtain process on the plantar surface of the tarsus. The fingers are well developed. I finger is turned back and has 2 phalanges, II -3, III -4, IV-5.

muscles

The skeletal muscles in birds are unevenly expressed on the body (Fig. 2). The subcutaneous muscles are well developed, gathering the skin into folds, which allows you to ruffle, lift and turn contour feathers.

Muscles of the head. The facial mimic muscles are absent.

The chewing muscles are more differentiated than in mammals and well developed. There are special muscles that act on the square bone and other movable bones of the skull (see bird skeleton). The muscles of the stem part of the body are well developed in the neck and tail. There are many short and long muscles on the neck, arranged in several layers. The peculiarities of the structure of the vertebrae, the mobility and the large length of the neck contribute to the extension, abduction and some rotation not only of the whole neck, but also of its individual sections, as a result of which the neck of the bird takes on an S-shape. The muscles of the thoracic and lumbosacral spine are not developed due to their immobility. The muscles of the chest and abdominal wall are the same as in mammals, with the exception of the diaphragm, which looks like a connective tissue film that does not completely separate the lungs from other organs.

Muscles of the chest highly developed and differentiated. These include several dozen muscles. The thoracic limb of birds is connected to the body not only by joints, but also by muscles in the area of ​​the shoulder girdle and shoulder. These are the most powerful muscles in the body. They make up to 45% of the mass of the muscles and perform the main work during the flight, raising, lowering, supinating, penetrating the wing, depending on the maneuver performed by the bird. These are such muscles as the superficial (large) pectoral muscle, subscapularis, coracoid-brachial and others.

Rice. 2. Chicken Muscles:

1 - chewing mm.; 2 - extensors of the neck and head; 3 - long neck m.; 4 - goiter; 5 - the longest m. of the neck; 6 - trapezoidal m.; 7 - the widest and. back; 8 - dentate ventral and; 9 - tailor's m.; 10 - tensioner of the wide fascia of the thigh; 11 - two-headed m. thighs; 12 - tail mm.; 13 - coccygeal gland; 14 - superficial chest m.; 15 - mm. wings; 16 - oblique external m. of the abdomen; 17 - calf m.; 18 - long fibular m; 19 - semitendinous m.; 20 - semimembranous m.; 21 - internal oblique m. of the abdomen; 22 - mm. anus and cloaca.

Muscles of the pelvic limb are also numerous. In the thigh area there are muscles of various functions that act on the hip joint. Of the muscles acting on the distal links of the limb, extensors and flexors are developed. Their tendons are usually ossified. When moving, due to the combined action of muscles on 2-3 joints, simultaneous extension and flexion of the joints occurs. Flexion is always accompanied by adduction of the fingers, extension - abduction. In chickens, the mechanism of sitting on a branch is well developed without the expenditure of muscle energy. This is a kind of tendon system, which begins with the tendon of the slender muscle, spreads over the patella, where it is attached to the tendon of the pectineal muscle, then passes to the lateral side of the lower leg, is fixed on the fibula, turns to the plantar surface and fuses with the tendons of the flexors of the fingers. This mechanism binds the joints so that when the knee joint is bent, the fingers are also bent.

How is a chicken made? What features of chicken anatomy would be useful for everyone to know? Let's take a look inside the most popular bird and take a fun anatomical tour together!

Skeleton structure

At least a rough understanding of how the skeleton of a chicken works will help the poultry farmer to conduct mandatory scheduled inspections of his livestock and diagnose various ailments in time. The chicken skeleton has the following feature: many bird bones are hollow inside. This is due to the fact that the chicken can fly, although it rarely does. The total weight of the bones of a domestic bird rarely exceeds 10% of body weight. The second feature is that the chicken has no teeth, instead it has a dense horny process - a beak.

The chicken skeleton is conditionally divided into the head section, trunk and limbs. The head of a feathered resident is very small, sometimes it looks very caricatured on a voluminous body. The cervical part of the spine consists of 13-14 vertebrae, the thoracic part of 7, the caudal part includes 5-6 movable vertebrae. The thoracic region also has such a specific component as the keel. The forelimbs of birds are better known to us as wings.

The wing of a chicken consists of the coracoid bone, scapula, clavicle and the so-called free wing (in its “composition” is the radius, ulna and humerus). The hind limbs of the chicken are clawed paws, the roosters are also equipped with dangerous spurs. The paws of poultry are attached to the pelvic girdle and consist of the lower leg, tibia and fibula, thigh and tarsus. Most often, a chicken has 4 fingers, but there are breeds for which the standard provides for a different number of fingers.

The laying hen is also characterized by the presence of a medullary bone, which roosters do not have. This component of the skeleton is involved in the formation of the eggshell.

Internal organs

The anatomy of the internal organs of poultry is also somewhat different from the structure of the internal organs of more familiar mammals. More about them below.

Digestive system

It begins with a beak, has such an interesting intermediate link as a goiter, and ends with a cloaca. The beak is intended solely for swallowing food; nature did not endow the birds with teeth, as they would significantly weight the head of the bird. It is precisely because primary fermentation of feed does not occur in the oral cavity of chickens that they need a goiter. There is an accumulation of food, which gradually moves to the muscular organ - the stomach, which has glandular and muscular sections.

The movement of food is carried out through the esophagus, it is a long muscular tube, the main function of which is transportation, because no enzymes and juices are released there. Fermentation begins directly in the glandular stomach, it is there that the strong acid and enzymes necessary for digestion are abundantly secreted. In addition, pebbles and sand can often be found in the stomach of a bird. Birds deliberately swallow such foreign objects. They become part of the bird's digestive system and help it grind roughage.

Digestive system: 1 - oral cavity, 2 - esophagus, 3 - goiter, 4 - glandular section of the stomach, 5 - muscular section of the stomach, 6 - duodenal intestine, 7 - pancreas, 8 - gallbladder, 9 - liver, 10 - intestine thin, 11 - ileum, 12 - blind processes, 13 - rectum, 14 - cloaca.

Further, the food moves into the duodenum and small intestine. There, useful substances and vitamins will be “taken” from it. Undigested food will form into feces in the large intestine, which ends in the cloaca. I must say that this is the only "way out" of the chicken body. The whole process of digestion in birds occurs very quickly, coarse grains are digested the longest.

Respiratory system

The unusual structure of the respiratory system is due to the fact that birds need a very large amount of oxygen during the flight. And, although the birds in our farmstead have practically lost interest in the sky, the structure of their respiratory system is atypical. The start of the respiratory system is the nostrils, then the air goes into the nasal cavity and larynx, then comes the trachea, which divides the air into two bronchi.

At the branching point of the trachea is the so-called lower larynx, which serves as an organ of sound production. The bronchi extend beyond the lungs and communicate with the multiple air sacs located in the bird's body. Air sacs are now found only in birds, presumably dinosaurs had them, so birds are often attributed to kinship with extinct reptiles. Most of the air inhaled by the bird "settles" in the air sacs, approximately 75%.

The lungs of chickens practically do not change their volume, they are not able to stretch as much as the lungs of mammals do. At the same time, the respiratory system of birds is not equipped with any valves; all air movements in it are subject to the laws of thermodynamics. In addition, air sacs serve for thermoregulation and gas exchange.

Circulatory system

The circulatory system of domestic birds is represented by a four-chambered heart, small and large circles of blood circulation. Moreover, both circles of blood circulation are disconnected and venous blood never mixes with arterial blood. Venous blood, collecting in the right atrium, passes into the right ventricle. Then, moving along the pulmonary artery, it enters the lung and, having been saturated with oxygen, returns to the left atrium. This is what the pulmonary circulation looks like.

The systemic circulation begins with the left ventricle, from where blood from the aorta will go to all organs and systems of the bird through many small blood vessels. I must say that the heart of the chicken is quite large compared to the size of the bird and looks asymmetrical. Its left side has more volume and does more "work". In addition, all birds have high blood pressure and rapid pulse.

This is due to the high body temperature of the bird and its rapid metabolism, requiring blood to circulate through the vessels at a solid rate. And then on the video you can admire walking poultry.

Selection system

The excretory system of the chicken is represented by paired kidneys, which communicate with the cloaca through the ureters.

An important feature of the anatomy: chickens do not have a bladder, and the absorption of water from urine occurs directly in the cloaca.

Due to the lack of a bladder, the appearance of chicken urine is atypical. It is thick and mushy and not always distinguishable from feces. At the same time, the number of bowel movements in a chicken is much greater than in mammals. This ensures the lightness of the body, necessary for birds in flight.

reproductive system

Chickens also breed differently than we do, our feathered friends are egg-laying. In males, the reproductive organs are the testes, located next to the kidneys. The testicles greatly increase in volume during the breeding of birds. From the testis, the seminal ducts depart, which end in the seminal vesicle - a receptacle for spermatozoa. Chickens do not have an external genital organ, fertilization is carried out by contact of the cloaca of a rooster and a chicken.

The female has only one ovary, the left one, which is adequately developed. It is also located near the kidney. The left oviduct departs from it, which opens with an expanded funnel into a convoluted thick-walled tube that communicates with the cloaca. The oviduct is divided into several sections: the upper one is called the fallopian tube, followed by a wide section called the uterus. From the moment the egg enters the oviduct until the hen lays the finished egg, it takes from 12 to 48 hours.

Nervous system

The nervous system of chickens is represented by the brain and spinal cord, as well as nerve processes and fibers, through which nerve impulses are transmitted through the body of the bird. The brain consists of the forebrain, diencephalon, midbrain and cerebellum. The hemispheres of the brain are small and do not have convolutions. Perhaps that is why they often talk about " chicken brains' as something insignificant.

The hemispheres of the brain carry out orientation in space and the implementation of the instincts of the chicken. The cerebellum is responsible for coordinating movements.

Video "Autopsy chicken"

The pathological anatomical autopsy of the chicken will complete our review!

When birds acquired the ability to fly, their structure underwent noticeable changes compared to that which was characteristic of their ancestors - reptiles. In order to reduce the body weight of the animal as much as possible, some of the organs became more compact, while others were completely lost. As for the scales, feathers have taken their place.

Those heavy structures that were vital were moved closer to the center of the body to improve its balance. In addition, the controllability, speed and efficiency of all physiological processes have increased markedly, which provided the flight power that the animal required.

bird skeleton

For the bird skeleton, the characters are unique rigidity and lightness. The lightening of the skeleton was achieved due to the fact that a number of elements were reduced (primarily in the limbs of birds), and also due to the fact that air cavities appeared inside some bones. Rigidity was provided by the fusion of a number of structures.

For convenience of description, the bird skeleton is divided into the axial skeleton of the limbs. The latter includes the sternum, ribs, spine and skull, and the latter consists of an arcuate shoulder and pelvic girdle with bones attached to them of the hind and anterior hips.

The structure of the skull in birds

The eye sockets of a huge size are characteristic of a bird's skull. Their size is so large that the brain box adjacent to them from behind is, as it were, pushed back by the eye sockets.

Very strongly protruding bones form a toothless upper and lower jaws, which correspond to the upper and lower mandibles. Under the lower edge of the eye sockets and almost close to them are the ear openings. Unlike the upper jaw in humans, the avian upper jaw is mobile due to the fact that it has a special, hinged attachment to the braincase.

The spine of birds consists of many small bones called vertebrae, which are located one after the other, starting from the base of the skull to the end of the tail. The cervical vertebrae are isolated, highly mobile, and at least twice as many as in most mammals, including humans. Due to this, birds can tilt their heads very strongly and turn it in almost any direction.

The vertebrae of the thoracic region articulate with the ribs and in most cases are firmly fused to each other. In the pelvic region, the vertebrae are fused into one long bone called the compound sacrum. Such birds are characterized by an unusually stiff back. The remaining caudal vertebrae are quite mobile, except for the last few, fused into a single bone called the pygostyle. In their form, they resemble the plow share and are the skeletal support for the long tail feathers.

Thoracic cage in birds

The heart and lungs of birds are externally protected and surrounded by ribs and thoracic vertebrae. Fast-flying birds are characterized by an extremely wide sternum, which has grown into a keel. This ensures efficient attachment of the major flight muscles. In most cases, the larger the keel of a bird, the stronger its flight. Birds that do not fly at all have no keel.

The shoulder girdle connecting the wings with the skeletal skeleton is formed on each side by three bones, which are arranged like a tripod. One leg of this design (crow bone - coracoid) rests against the sternum of the bird, the second bone, which is the shoulder blade, lies on the ribs of the animal, and the third (collarbone) merges with the opposite clavicle into a single bone called the "fork". The scapula and coracoid in the place where they converge form the articular cavity, in which the head of the humerus rotates.

The structure of the wings of birds

In general, the bones of a bird's wings are the same as the bones of a human hand. Just like in humans, the only bone in the upper limb is the humerus, which articulates at the elbow joint with the two bones (ulna and radius) of the forearm. Below the brush begins, many elements of which, unlike their human counterparts, are merged or completely lost. As a result, only two bones of the wrist remain, one buckle (metacarpal bone of a large size) and four phalanges, which correspond to three fingers.

The bird's wing is much lighter than the limb of any other terrestrial vertebrate similar in size to a bird. And this is not only due to the fact that the bird brush includes fewer elements. The reason is also that the long bones of the forearm and shoulder of the bird are hollow.

Moreover, in the humerus there is a specific air sac, which belongs to the respiratory system. Additional relief to the wing is given by the fact that there are no large muscles in it. Instead of muscles, the main movements of the wings are controlled by the tendons of the very developed musculature of the sternum.

Flying feathers extending from the hand are called primary (large) flight feathers, and those that are attached in the region of the ulna of the forearm are called secondary (small) flight feathers. In addition, three more wing feathers are spilled, which are attached to the first finger, as well as covering feathers, which smoothly, like a tile, lean on the bases of the flight feathers.

As for the pelvic girdle of birds, on each side of the body it consists of three bones fused together. These are the ilium, pubic and ischium bones, and the ilium is fused with the sacrum, which is complex in structure. This complex design protects the kidneys from the outside, while providing a strong connection between the legs and the shoulder skeleton. Where the three bones belonging to the pelvic girdle converge with each other, there is a significant depth of the acetabulum. It rotates the head of the femur.

The device of the legs in birds

Like humans, the femur of birds is the core of the upper lower limbs. The lower leg is attached to this bone at the knee joint. But if in humans the small and large tibia are included in the lower leg, then in birds they are fused with each other, as well as with one or several tarsal bones. Together, this element is called tibiotarsus. As for the fibula, only a short thin rudiment remained visible from it, which is adjacent to the tibiotarsus.

Bird foot arrangement

In the intratarsal (ankle) joint, the foot, which consists of one long bone, the bones of the fingers and the tarsus, is attached to the tibiotarsus. The latter is formed by elements of the metatarsus, which are fused together, as well as by several tarsal lower bones.

Most birds have four fingers, each of which is attached to the tarsus and ends with a claw. The first finger of birds is turned back. The remaining fingers in most cases are directed forward. Separate types have a second or fourth finger facing back (like the first). It should be noted that in swifts the first finger, like the rest of the fingers, is directed forward, while in the osprey it can turn in both directions. The tarsus of birds does not rest on the ground, and they walk only on their toes, not resting on the ground with their heels.

Muscular system in birds

The legs, wings, and other parts of the bird's body are driven by approximately 175 different skeletal striated muscles. These muscles are also called voluntary, since their contractions can be controlled by consciousness and, accordingly, they can be voluntary. As a rule, these muscles are paired, located symmetrically on the right and left sides of the body.

The main muscles that provide flight are the pectoral muscle and the supracoracoid. Both muscles start on the sternum. The largest muscle is the chest. She pulls the wing down, causing the movement of the bird in the air up and forward. And the supracoracoid muscle lifts the wing up, in the direction opposite to the work of the pectoral muscle, preparing it for the next stroke. I must say that in turkey and domestic chicken, these two muscles are considered "white meat", while the rest of the muscles are "dark meat".

In addition to skeletal voluntary muscles, birds, like other vertebrates, have smooth muscles, which lie in layers in the walls of the organs of the genitourinary, digestive, vascular and respiratory systems. In addition, there are smooth muscles in the skin. It is they who determine the movement of feathers. There are also smooth muscles in the eyes: thanks to it, the image is focused on the retina. Such muscles, in contrast to the striated muscles, are called involuntary muscles, since they work without volitional control.

Nervous system in birds

The central nervous system of birds consists of the spinal cord and brain, formed by many neurons of nerve cells.

The most prominent part of the brain in birds are the cerebral hemispheres, which are the center in which higher nervous activity takes place. The surface of these hemispheres has neither convolutions nor furrows typical of many mammals, and its area is quite small, which coincides with the relatively low intelligence of the majority of birds. Inside the cerebral hemispheres are the centers of coordination of those forms of activity that are associated with instinct, including the instincts of feeding and singing.

Of particular interest is the avian cerebellum, which is located immediately behind the cerebral hemispheres, and is covered with convolutions and furrows. Its large size and structure correspond to the complex tasks that are associated with maintaining balance in the air and coordinating the many movements necessary for flight.

The cardiovascular system in birds

In relation to body size, the heart of birds is noticeably larger than that of mammals of the same size. At the same time, it was noted that the smaller a particular species of bird, the larger its heart will be (of course, relative to the size of its body). For example, in a hummingbird, the mass of the heart is 2.75% of the mass of the entire body. This is necessary so that all perennial birds can provide rapid blood circulation. The same applies to those species of birds that live at high altitudes or in cold areas. And, just like mammals, birds have a four-chambered heart.

The heart rate depends on the size of the heart and the animal itself, as well as on the degree of load. For example, the heart rate of a resting ostrich is about 70 beats per minute, while in a hummingbird it rises to 615 beats per minute during flight. At the same time, excessive fright can frighten the bird so much that the increased pressure can cause the arteries to burst and the bird to die.

Just like mammals, birds are warm-blooded animals. At the same time, the range normal temperatures of their bodies, they are higher than that of humans and range from 37.7 to 43.5 degrees. As a rule, avian blood contains more red blood cells than the bulk of mammals. Thanks to this, the bird's blood can carry more oxygen per unit of time, which is very important for flight.

Respiratory system in birds

In almost all birds, the nostrils lead to the nasal cavities located at the base of the beak. But there are exceptions: gannets, cormorants and some other species of birds do not have nostrils and therefore are forced to breathe through their mouths. Air entering the nose or mouth moves into the larynx, behind which the trachea begins.

Unlike mammals, the larynx of birds does not produce sounds, being only a valve apparatus that protects the lower respiratory tract from water and food entering them.

Closer to the lungs, the trachea divides into two bronchi, which enter one each lung. At the point where they separate, the lower larynx is located, which serves as the bird's vocal apparatus. It is formed by ossified dilated bones of the trachea and bronchi, as well as internal membranes. Pairs of special singing muscles are attached to them. When the air exhaled from the lungs passes through the lower larynx, it causes the membranes to vibrate, which produces sounds. Those birds that are characterized by a wide range of emitted tones have more singing muscles that strain the vocal membranes than those species that sing frankly poorly.

Each bronchus divides at the entrance to the lungs into thin tubes. The walls of these tubes are permeated with blood capillaries, which receive oxygen from the air and give carbon dioxide back into it. These tubules are sent to thin-walled air sacs, resembling capillary-free bubble. These bags are located outside the lungs - in the pelvis, shoulders, neck, around the digestive organs and lower larynx, and even stick into the large bones of the wings and legs.

When a bird inhales, air enters these same sacs through the tubes, and when it is exhaled, it travels from the sacs through the tubes through the lungs, where gas exchange occurs again. Thanks to this double breathing, the supply of oxygen to the body increases, which creates more favorable conditions for flight.

In addition, air sacs humidify the air and also regulate body temperature. This is achieved due to the fact that as a result of evaporation and radiation, the surrounding tissues can lose heat. As a result, birds acquire the ability, as if to sweat from the inside, which is a worthy compensation for the absence of sweat glands in birds. In addition, air sacs help remove excess fluid from the body.

The structure of the digestive system in birds

In general, we can say that the digestive system of birds is a hollow tube extending from the beak up to the opening of the cloaca. This tube performs many functions at once, taking in food, secreting juices with enzymes that break down food, absorb substances, and also bring out undigested food residues. However, despite the fact that all birds have the same structure of the digestive system, as well as its functions, there are differences in some details that are associated with feeding habits, as well as with the diet of a particular group of birds.

The process of digestion begins with the entry of food into the mouth. The majority of birds have salivary glands that secrete saliva that wets food, and digestion of food begins with it. In some birds, such as swifts, the salivary glands secrete a sticky fluid that is used to build nests.

The functions and shape of the tongue, however, as well as the beak of a bird, depend on the lifestyle of a particular species of birds. The tongue can be used both for holding food in the mouth and for handling it in the mouth, as well as for tasting and feeling food.

Hummingbirds and woodpeckers have very long tongue, which they can protrude far beyond their beak. Some woodpeckers have notches pointing backwards at the end of their tongues, thanks to which the bird can pull out insects and their larvae that are in the bark to the surface. But the tongue, as a rule, is bifurcated at the end and rolled into a tube, which helps to suck nectar from the flowers.

In pheasants, grouses, and turkeys, as well as in some other birds, part of the esophagus is permanently enlarged (called a goiter) and is used to store food. In many birds, the esophagus is sufficiently distensible and can accommodate a significant amount of food for some time before it enters the stomach.

The stomach in birds is divided into a glandular and muscular ("navel") part. The glandular part secretes, splitting food into substances suitable for subsequent absorption, gastric juice. The muscular part of the stomach is characterized by thick walls and hard internal ridges that grind food that is obtained from the glandular stomach, which performs a compensatory function for these toothless animals. Muscular walls are especially thick in those birds that feed on seeds and other solid foods. Since some of the food that has entered the stomach may be undigested (for example, solid parts of insects, hair, feathers, parts of bones, etc.), then in many birds of prey in the "navel" rounded flat pellets are formed, which burp from time to time.

Continues digestive tract the small intestine, which immediately follows the stomach. This is where the final digestion of food takes place. The large intestine in birds is a thick straight tube leading to the cloaca. In addition to it, the ducts of the genitourinary system also open into the cloaca. As a result, both fecal matter and sperm, eggs and urine enter the cloaca. And all these products leave the body of the bird through this one hole.

The genitourinary system in birds

The genitourinary complex consists of the excretory and reproductive systems, which are very closely related. The excretory system functions continuously, while the second one is activated only at certain times of the year.

The excretory system consists of a number of organs, among which, first of all, two kidneys should be mentioned, which extract waste products from the blood and form urine. Birds do not have a bladder, so urine through the ureters enters directly into the cloaca, where the bulk of the water is again absorbed into the body. The white porridge-like residue left after that, together with the dark-colored feces that came from the large intestine, is thrown out.

The reproductive system in birds

This system consists of the sex glands (gonads) and the tubes that extend from them. Male gonads are represented by a pair of testes, in which gametes (male sex cells) are formed - spermatozoa. The shape of the testes is either elliptical or oval, with the left testis usually larger than the right. The testicles are located in the body cavity near the anterior end of each kidney. With the approach of the mating season, the pituitary hormones, due to their stimulating effect, increase the testes by several hundred times. The spermatozoa from each testicle enter the seminal vesicle through the vas deferens, which is thin and tortuous. It is there that they accumulate, remaining until copulation and the ejaculation that occurs at that moment. At the same time, they enter the cloaca and go out through its opening.

The ovaries (female gonads) produce eggs (female gametes). The bulk has only one (left) ovary. The egg cell, when compared with a microscopic sperm cell, has a huge size. In terms of mass, its main part is the yolk, which is a nutrient material for the embryo that began to develop after fertilization. The egg from the ovary enters the oviduct, the muscles of which push the egg past all kinds of glandular areas located in the walls of the oviduct. With their help, the yolk is surrounded by protein, shells under the shell and consisting mostly of calcium shell. At the end, pigments are added that color the shell in one color or another. It takes about a day for an egg to develop an egg ready for laying.

Birds are characterized by internal fertilization. During copulation, sperm enter the female's cloaca and then move up the oviduct. Female and male gametes (that is, the actual fertilization) occurs at the upper end of the oviduct even before the egg is covered with protein, shell membranes and shells.

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