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

Fig. 251. Brisket of a goose:

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

Fig. 252. Pelvis and lumbar

sacral spine

chicken from the ventral side.

and- lumbosacral spine; B-the last rib; from-ilium; d-ischium; e-one bone; / -blocked hole.

(fig. 250- 20; 251-d ").Its size is determined by the degree of massiveness of the pectoral muscles, thanks to which the flight is mainly carried out; in running birds (ostriches) the crest is absent. The posterior edge of the sternum has a pair of incisura sterni of various sizes. Have ducksit is oval and small, while geese(fig. 251- e)at the back completely closes into the hole. Have chickensthe notch is very deep, triangular in shape, so that its lateral border forms a long lateral process (Fig. 250- 21). Next to it, the chickens have a clearly defined costal process. (23). The lateral edges of the sternum have fossae for articulation with the sternal portions of the ribs, and at the cranial edge on the right and left it 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 from 11 to 14 segments that grow together soon after their development in the os lum-bosacrale. The first of them, as indicated, merges with the last thoracic vertebra, and the posterior one, with the row (from the 3rd to the 7th) of the caudal vertebrae. In addition, part of this monolithic vertebral mass is so completely connected to 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

REGULATORY TRAFFIC SYSTEM

the transverse ridge 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 in chickens, in ducks and geese from seven clearly defined and mobile vertebrae (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 the tail feathers are fixed.

Head skeleton

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

The cerebral section of the skull consists of early accrete bones: the 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).

Wedge soldering -os sphenoidale-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 an articular surface at its base for articulation with a square bone.

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

The frontal bones - ossa frontalia - are significantly developed 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 edge.

The facial part of the skull of birds is more complex, but its volume in most of them is small in comparison with the brain part. Its lightness is due mainly to the absence of teeth, which is very characteristic of 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 fused into one whole formation, which is mobile in relation to the brain section, creating the skeleton of the bird's beak. The facial part of the skull includes: incisor and nasal bones, dorsal jaw, vomer, palatine, pterygoid, square-zygomatic and square bones, as well as a complex ventral jaw.

Incisor bones and-ossa incisiva (Fig. 250- 1) - even before the chick hatches, they merge into one, the most massive bone of the beak. It gives off paired, backward processes: 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 jaw and maxillae are poorly developed, toothless and also participate in the formation of the frame 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 a 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 beak on the right and left between the frontal processes of the incisor bones and the dorsal jaw. They limit the nasal opening at the back.

The nasal cavities are separated from each other by a nasal septum, supplemented ventrally with a vomer. Oral site nasal

Fig. 253. Scheme of the skeleton of a goose's head. AND-with a closed beak, IN-with an open beak.

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

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

bone: 5 - scion.

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

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

Palatine bone and-ossa palatina (Fig. 253- 1) -participate in the formation of a hard palate and restrict choanas, separated by a vomer. They are mobile and connected in front by a joint with the dorsal jaws, and behind them with the pterygoid bones. In general, the palatine bones are one of the links in the movable chain between the square bone and the beak.

Pterygoid bone and-ossa pterygoidea {3) - rather 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 middle sagittal line, they are connected by a joint not only with the posterior ends of the palatine bones, but also with the sphenoid bone.

voluntary organ system

Their posterolateral ends are also articulated with square bones. Thus, a chain of mobile palatine and pterygoid bones is located between the frame of the beak and the square bones.

Zygomatic arch -arcus zygomaticus (2) -connected with the front end with the dorsal jaw of the beak, and with the rear end with the square bone. The arch consists of two bone elements; of these, the anterior one is called the zygomatic bone-os iugale, and the posterior-quadra-zygomatic bone-os quadra-toiugaie.

Square bones - ossa quadrata (4) - irregular, approximately rectangular 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 quadrangular.

The ventral jaw b-mandibula-formed as a result of the fusion of six bones, which are also present in reptiles. The anterior, most developed, part of it is called the dentary-os dentale, and the posterior-articular bone-os articulare. In between are: os complementare, os operculare, os angulare and os supraangu-lare. They all merge with each other. In the area of \u200b\u200bthe articular bone, the ventral jaw is connected by a joint to the square bone. A slightly curved process protrudes from the jaw behind the articulation (5) to attach the muscle that opens the jaw. This shows how complex the construction of the jaw joint of birds is (see the section on musculature for its mechanism of action).

Fig. 254. Hyoid bone.

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

The 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 site to-basihyoid (6), in front of which there is an intralingual bone-os endoglossum (a),-giving the basis of the tongue, and back- keel-carina (c), - where it reaches the trachea. Long (two- or three-membered) branches extend from the main site, enveloping the skull, but not directly related to it.

Skeleton of the chest limbs

The pectoral limb of birds is strongly changed in comparison with the limbs of the monotonous shape of the ancestors of birds and is called the wing. It, like a legged limb, can be subdivided 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 to each other and abut against the sternum through the coracoid. Such a design creates strength with the ability to make large and strong wingspan with the free part of the wing in the segmental plane during flight.

L about p and t to and-scapula (Fig. 250- 27) - has the appearance of a slightly curved narrow plate, devoid of scapular cartilage. It is located obliquely backward 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 inbelt 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 medial to the sternum. The humerus end of the bone is connected to the scapula, the humerus, and a taut joint with the clavicle.

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

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

Humerus 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 (humeral) end in the form of a slightly convex oval head is connected to the 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 medial (or large) tubercles. Here, on the medial side, there is a foramen pneumaticum opening 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.

Forearm bones i-ossa antebrachii. Strong in the forearm link. the ulna is developed (35). It is slightly curved and supplied with a poorly defined olecranon process. Nearly straight, thinner radius-radius (34) - lies dorso-medially. A fairly wide interosseous space (spatium interosseum) remains between both bones. The forearm, when the wing is at rest, is located almost parallel to the shoulder, that is, from the elbow joint it is directed forward.

Distal wing linkcorresponding to the front paw (hand) of leg-shaped limbs, it is highly modified and adapted to a one-sided flight function. This change was expressed in the reduction of individual members in all sections of this link. When the wing is at rest, the link itself lies at an acute angle to the forearm and its distal end is directed backward and slightly lowered downward.

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

P i st-carpometacarpus (56) -reduced to three segments (2,3, 4th), and even those are fused together into one formation, to which the distal row of the wrist is also accreted. Of these, the most noticeable are the 3rd and 4th metacarpal bones, fastened by their ends and having an interosseous space between them. The second small metacarpal bone is completely fused with the proximal end of the adjacent one.

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

918 REGULATORY TRAFFIC SYSTEM

Biological features of poultry

The most characteristic features of birds, which distinguish them from other vertebrates, are the ability to fly and the intensity of life processes.

The ability to fly was reflected in the entire organization of the birds. In flight, the bird makes a huge number of movements, which is accompanied by high energy consumption and intensive metabolism, which also determines a high constant body temperature (on average 42 ° C), which requires intensive work from the heart. The number of heart beats 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 system of air sacs, their volume is several times the volume of the lungs. Air bags play important role in thermoregulation, moisture evaporates from their surface through the respiratory tract, which prevents the body from overheating. Since birds do not have sweat glands and evaporation of moisture occurs through the respiratory organs, 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 - cuticle.

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

Birds have good eyesight and excellent hearing. The chicken's field of view is 300 o.
Poultry have completely or partially lost their ability to fly. Her productivity has increased many times over.
There is no seasonality of laying.

Skeleton

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

The chicken skeleton is made up of bones and cartilage connected by ligaments and forms the solid foundation of the body.

The bones of the chicken skeleton also serve as a place of accumulation of mineral salts necessary for the life of the body and, in particular, for the formation of eggs. In this case, minerals are constantly consumed and at the same time replenished due to substances obtained by chickens with feed. 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.

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

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

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

The trunk skeleton is subdivided into cervical, thoracic, and lumbosacral (pelvic) sections. The cervical region in chickens is the largest. There are 13-14 vertebrae in it, movably connected. Thanks to this, the chickens' neck is long and very mobile, which is of great importance for foraging, cleaning and lubricating feathers. The thoracic region is the rib cage, 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) is attached to the lumbosacral region. Five pairs of ribs are fused with the sternum and due to this 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 brisket in chickens has a strongly developed ridge, or keel. Powerful pectoral muscles are attached to it, which set 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 breastbone.

There are 11-14 vertebrae in the lumbosacral region of chickens, but it is not easy to distinguish them. Even at a young age of the bird, they tightly grow together not only with each other, but also with the last thoracic, as well as the first caudal vertebra, 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 sedentary connections. The last caudal vertebra is the largest and has a special shape. It is called the coccyx (pygostyle).

The skeleton of the wing consists of the bones of the shoulder girdle and the bones of the wing itself. The shoulder girdle includes the scapula, collarbone, and caracoid bone. They serve for the flexible connection of the wing with the skeleton. In the wing itself there are the following bones: the humerus, two bones of the forearm - a thicker ulna and a thinner radius, two bones of the wrist, a metacarpal bone and three poorly developed bones of the fingers.

The pelvis consists of paired lamellar bones: the iliac, ischial and pubic. The ilium of the pelvis is motionlessly connected to the sacrum bone. Unlike mammals, the pubic bones of a bird are not connected to each other. In rushing chickens, they seem to soften, become elastic and diverge from each other at a considerable distance. By the magnitude of this distance, one can judge whether the chicken is laying or not. The more intense the egg-laying in the hen 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 lies in the presence of a medullary bone in chickens, it is involved in the formation of eggshell.

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

Digestive system

The chicken digestive system has its own characteristics. The digestive organs include the beak, mouth, pharynx, esophagus, goiter, glandular and muscular stomachs, intestines and cloaca. The beak and oral cavity are designed exclusively for the capture of food, as well as its transmission into the esophagus and further into the stomach. The chicken can swallow food in any position of the head, even if it is down. This is provided by the horny teeth on the tongue and palate of the chicken. But she swallows water only with her head raised. 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 structure that allows the chickens to raise their heads above the drinking bowl to a height sufficient to swallow water.

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

The lack 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 in abundance secrete strong acid and some enzymes that start the process of digesting 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 gizzard, 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, the jejunum, and the ileum. In its wall, there are wall - general intestinal - glands. The glandular glands are the liver and pancreas. Birds do not have duodenal glands. In the intestine there are long villi, and its mucous membrane is collected in folds that increase the path of food through the intestine.

The duodenum extends from the anterior portion of the stomach muscle to the pelvis, and then returns to form a loop of two knees. The pancreas is located in this loop.

The jejunum and ileum are suspended on a thin mesentery, touching each other and forming spiral curls. Ileum - opens into the posterior colon at the border of the cecum 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.

The pancreas is located in the loop of the duodenum, has three lobes and three ducts in chickens.

The hind gut, or the large intestine, does not have a colon of birds. Chickens have two blind intestines. Their apexes are facing cranially, and they are delimited from the ileum by a circular fold. The rectum passes into the cloaca, which is divided into three sections by two transverse folds: anterior, middle and posterior. The rectum opens into the anterior section, the ureters, vas deferens (in males) and oviducts (in females) - in the middle. The posterior part of the cloaca ends with the anus, through which undigested food residues 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 (fabricated) bursa, which is reduced in adult birds.

Chicken stomach outside

Cutaway of a chicken stomach

The duration of the presence of feed in the digestive tract of the chicken depends on many conditions, and above all on its preparation for feeding. Whole grains are the longest in the digestive organs and least of all 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-rushing adult chickens - in 8, in laying, but low-producing chickens - in 3 hours, and in high-producing chickens in just 2. These features must be taken into account when organizing bird feeding. That is why it is advisable to feed highly productive chickens with compound feed without restriction during the day. For the same reason, the best food is considered to be balanced in all nutrients, loose or granular compound feed, 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 the nutrients to maintain life, body growth and egg formation. But in the process of constant metabolism that takes place 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 is performed by 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 located on both sides of the lumbar vertebrae. Inside them there are the so-called renal glomeruli, enveloped in a dense network of the finest blood vessels - capillaries. Here, passing through the capillaries, the blood gives off excess fluid and substances harmful to the body, which are then secreted into the urinary tubules of the kidneys, forming urine.

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

Reproductive system

Males have two testicles located inside the body. 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 the female come into contact. Males do not have an organ that penetrates the female's body. In females, only the left ovary and oviduct usually function. The eggs pass through the reproductive tract from the ovary. The sperm cell follows this path and fertilizes the egg at the very beginning of the process. Sometimes the sperm can remain viable in the female's body for up to three weeks after mating.

The time a pullet hen lays the first egg is considered to be the time of puberty. It can come earlier or later, depending on the breed, as well as the individual characteristics of the given chicken. In chickens of egg breeds, sexual maturity is usually observed at the age of about five months, and in chickens 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 long daylight hours - more than 14 hours per day, chickens of egg breeds can be carried at the age of about 130 days, having not yet completed their growth and general physiological development. As a result, such chickens later become poor layers. They lay smaller eggs and decrease egg production rather quickly. Therefore, it is not recommended to artificially induce early puberty in chickens. It should occur only after the pullet hen has basically completed its growth, fully developed, and its bones and organs have accumulated sufficient reserves of minerals, nutrients and vitamins.

At the beginning of oviposition, chickens lay smaller eggs, then their weight gradually increases and reaches normal values \u200b\u200bby 10-12 months of age. Therefore, to characterize chickens, the weight of the eggs is determined at one year of age. Chickens lay the largest number of eggs in the 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 chickens begins at 5 months of age, usually to obtain eggs, they are kept up to 17-18 months, and sometimes 19-22 months of age. Oviposition may stop prematurely if the hen begins to show the hatching instinct - to cluck. But in chickens of egg breeds, especially in Leghorns, thanks to long selection work carried out with them, this instinct has almost disappeared.

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

Chicken reproductive system

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 in direct proportion to 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 hillocks of a well-developed midbrain.

The leading role in all life processes of any organism is played by the nervous system. The nervous system connects the body with the environment. All irritations coming from the outside are perceived by her through the senses. In response to these stimuli, the functions of various organs change, the organism adapts to the environment. A sufficiently strong irritation in any part of the nervous system usually causes numerous reflexes, which determine the reaction of the body as a whole.

A reflex is the body's response 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 conditioned and unconditioned. Acquired reflexes are called conditional; they can occur throughout the life of a bird. Unconditioned reflexes are those that are innate and inherited. The unconditioned reflexes include the sexual reflex, the defensive reflex, and many others. Conditioned reflexes are strictly individual and unstable, that is, they can disappear without a systematic stimulus and appear again.

Sometimes, under the influence of extreme stimuli, a state of general tension in 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, taking away decay products from them. Blood helps to regulate body temperature, maintain a certain chemical composition... The secretions 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 ensure the body's immunity (immunity) to infectious diseases.

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

The bird's heart works like a pump, pumping blood throughout the body and supplying oxygen to its cells. The heart of birds resembles the heart of mammals, although at the same time it is asymmetric: its left half is more developed than the right, since it does more work. The heart beats faster in birds than in mammals of approximately equal size.

The average temperature of birds is 42 o 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 cools down continuously, 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 for continuous heating of the body.

Respiratory system

In terms of the structure of the respiratory system, birds differ from all other vertebrates. The lungs of birds resemble a sponge, completely penetrated by numerous thin branching canals - parabronchs. Many special thin-walled cavities are connected with the lungs of birds - air sacs that penetrate literally all corners of the bird's body and exceed the lungs by 3-4 times in total volume. There is no gas exchange in the air bags; they are intended exclusively for storing and redistributing air in the bird's respiratory system.

It is the presence of these volumetric reservoirs that provides the main feature of the breathing of birds - the continuous flow of air through the parabronchi rich in blood vessels, where the blood is enriched with oxygen and gives off 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 goes continuously 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-exhalation. Such a respiratory system ensures almost continuous oxygen saturation of the blood and its uninterrupted flow to tissues. The lungs of chickens practically do not change in size and do not have the same ability to stretch as the lungs of mammals.

1. Anatomy of pets / A.I. Akaevsky, Yu.F. Yudichev, N.V. Mikhailov, I. V. Khrustaleva. - M .: Kolos, 1984.543 p. (Textbooks and teaching aids for higher agricultural educational institutions).

2. Vrakin V, F., Sidorova MV The 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 IV, Mikhailov NV, Shneyberg Ya.I. and other Anatomy of pets / Under the general. Ed. I.V. Khrustaleva. M .: Kolos, 1994.S. 87-115.

Ministry of Agriculture Russian Federation

FGOU VPO Tyumen State Agricultural Academy

Department of Anatomy and Physiology

Bird Anatomy

Toolkit

To laboratory and practical exercises

for students of the specialty "Veterinary Medicine"

Tyumen 2011

The methodological guide was compiled by Cand. vet. Sciences, Associate Professor of the Department of Anatomy and Physiology of the TSAA Veremeeva S.A.

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

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

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

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

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

3. The skin and its derivatives ……………………………………… .10

4. The digestive apparatus ………………………………………………… ..11

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

6. Apparatus for urination and reproduction ……………………………… 14

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

8. Endocrine glands ………………………………………… ..16

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

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

Introduction

Features of the anatomical structure of birds

The class of birds is subdivided into keel and ratite. Poultry - keeled birds belong to two orders: chickens (chickens, turkeys, guinea fowls) and anseriformes (geese, ducks). Birds, due to their adaptability to flight, have a number of specific features in the structure of the organism. In their development, they are closer to reptiles. Birds, like reptiles, do not have skin glands, horny skin derivatives (feathers, scales, horny beak, claws) are highly developed, a typical lower zygomatic arch, a 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, metatarsal articulation on the pelvic limb, a similar structure of the kidney, etc. Birds are better developed than 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 way of traveling - flying - left an imprint on their entire organization. These features were dictated by the need to subordinate the shape 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 body contour, the thoracic limb has turned into a wing - a specialized aircraft. The bones are strong and light, often pneumatized, the head is relieved by the absence of teeth. The cervical region is elongated and very mobile, performing together with the head the role of the front rudder, grasping limb and providing all-round visibility. The thoracolumbar region is short and inactive, the tail section is turned into a base for the tail feathers. The musculature is extremely uneven, providing mainly flight and walking. The internal organs are 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 congestive 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 vital activity of birds. Facilitation of the excretory system - absence of the bladder, reproduction - one ovary and oviduct, external development embryo.

Skeleton

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

Skull(fig. 1). The cerebral section of the skull is formed by unpaired occipital, sphenoid, ethmoid and paired temporal, parietal, 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. Large eyes have a great influence on the shape of the bird's skull. Under their pressure, the orbital wings of the sphenoid bone grow together with each other and with the perpendicular plate of the ethmoid bone and become the interorbital septum. As a result, the cerebral section of the skull does not extend rostrally beyond the orbits. The occipital bone has one condyle, which significantly increases the mobility of the head.

The facial section is more complex. It is formed by paired incisors (intermaxillary), maxillary, nasal, lacrimal, palatine, zygomatic, pterygoid, square, mandibular and unpaired vomer, hyoid bones. The incisor, maxillary and nasal bones form the bony frame of the upper beak - the beak. The nasal bones look like a thin springy plate, which joins (in goose joints) to the frontal and lacrimal bones and allows you to lift up the beak. This movement occurs simultaneously with the lowering of the lower jaw - mandible due to the development of the lower zygomatic arches and the mobility of the square 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 the several joints formed by them, form a good grasping mechanism of the bird's beak.

Spinal column skeleton(fig. 1) . The cervical region in birds of different species has a different number of vertebrae: in chickens and turkeys - 13-14; in ducks -14-15, in geese - 17-18. The cervical vertebrae are mobile, have short spinous and well-developed transverse processes, rib rudiments in the form of costal processes. The complex relief of the heads and fossae 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. Chickens have 7, and ducks have 9 thoracic vertebrae, the same number of pairs of ribs and sternum. Vertebrae 2 to 5 have grown together into a single vertebral, or dorsal, bone. 1st and 6th vertebrae are free. 7th merged with the first lumbar.

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

Fig. 1. Chicken skeleton:

1 - incisor (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 - clavicle; 12 - scapula; 13 - back bone; 14 - asternal and 15 - sternal ribs; 16 - hooked process; 17 - body; 18 - costal lateral and 20 - middle processes of the sternum; 21 - her comb; 22 - humerus, 23 - shoulder, 24 - ulnar, 25 - carpal ulnar and 26 - carpal radius; 27 - II finger; 28 - metacarpal bones; 29 - III finger; 30 - IV finger; 31 - the ilium; 32 - sciatic foramen; 33 - caudal vertebrae; 34 - pygostyle; 35 - ischial and 36 - pubic bones; 37 - locked hole; 38 - femur; 39 - knee cup; 40 - fibular, 41 - tibia, 42 - metatarsal and 43 - metatarsal bones; 44 - I finger; 45 - II finger; 46 - III finger; 41 - IV finger.

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

The sternum is a flat bone concave at the top. Its body is elongated in the caudal direction and bears a crest - keel on the ventral surface. 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.

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

In the tail section, chickens have 5, and ducks have 7 non-fused vertebrae. The last 4-6 vertebrae grow together into a pygostyle - a flat triangular bone, to which the tail feathers are attached.

Thoracic limb skeleton(fig. 1) . Due to its adaptability to flight, the thoracic limb has 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 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 grow together, which is why a fork is formed.

The coracoid bone is the most powerful of the bones in the girdle. Located almost at right angles to the scapula and parallel to the clavicle. The bone is pneumatic. The proximal end is articulated with the scapula, clavicle and humerus, distal 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 the flight feathers. On the distal epiphysis, there are two articular surfaces for articulation with the wrist bones and one with the radius. The radius is smaller than the ulna, it looks like a cylindrical rod. There is a wide interosseous space between them.

The bones of the hand are strongly reduced. Of the carpal bones, only the carpal radius and carpal ulnar bones have survived. The intermediate bone is fused with the radial carpal bone, the accessory bone with the ulnar carpal bone. The hands of the distal row fused with the bones of the metacarpus, which were also partially reduced and fused. Metacarpals II, III and IV and bones of the distal series of the wrist fused into a single metacarpal-carpal bone or buckle. In the buckle, the largest part is formed by the third metacarpal bone. Bone II looks like a small tubercle. Between the III and IV bones of the metacarpus, the interosseous space. Of the fingers, III is more developed, which consists of two phalanges, in II and IV fingers, one phalanx is developed. The second toe is the bone base of the winglet.

Pelvic limb skeleton(fig. 1). The skeleton of the pelvic girdle consists of the ilium, pubic and ischial bones, fused and the pelvic bone. All 3 bones are involved in the formation of the glenoid cavity. The ilium lies along the lumbosacral bone, with which it fuses. Strongly tilted downward. The cranial part of the bone is concave; the gluteal muscles lie here. The caudal part is convex; the kidneys are located under it. The impoverished and ischial bones grow to the caudal edge of the ilium.

The ischium is an elongated triangle. The pubic bone is in the form of a long, thin, curved rod 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 thigh, shin bones and foot. The femur is long, tubular, pneumatic. Of the tibia bones, the tibia is better developed, which also fuses with the tarsal bones and forms the tibia-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 fingers, have grown together. There is no tarsus. The proximal row of the tarsus became part of the tibia-tarsal bone, the distal and central rows merged with the metatarsal bones, 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, there is a triple block for articulation with the bones of the fingers. At the distal end of this bone, an independent I metatarsal bone lies in the form of a pea. Roosters have a curtain process on the plantar surface of the tarsus. The toes are well developed. I finger is turned back and has 2 phalanges, II -3, III -4, IV-5.

Muscle

The skeletal muscles of birds are unevenly expressed on the body (Fig. 2). The subcutaneous muscles are well developed, collecting the skin in folds, which allows ruffling, lifting and turning the contour feathers.

Muscles of the head... Facial mimic muscles are absent.

The chewing muscles are more differentiated than in mammals and well developed. There are special muscles acting on the square bone and other movable bones of the skull (see bird skeleton). The muscles of the trunk of the body are well developed in the neck and tail. There are many short and long muscles on the neck, located in several layers. The structural features of the vertebrae, mobility and long neck length contribute to extension, abduction and some rotation of not only the entire neck, but also its individual sections, as a result of which the bird's neck takes an S-shaped appearance. 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 pectoral limb highly developed and differentiated. These include several dozen muscles. The pectoral limb of birds is connected to the trunk not only by joints, but also with the help of muscles in the region of the shoulder girdle and shoulder. These are the most powerful muscles in the body. They make up 45% of the muscle mass and perform the main work during the flight, raising, lowering, supinating, piercing the wing, depending on the maneuver made by the bird. These are muscles such as the superficial (large) pectoral muscle, subscapularis, coracoid-brachialis and others.

Fig. 2. Chicken muscle:

1 - chewing mm .; 2 - extensors of the neck and head; 3 - long m. Neck .; 4 - goiter; 5 - longest m. Neck; 6 - trapezoidal m; 7 - the broadest and. back; 8 - dentate ventral and; 9 - tailor m .; 10 - tensioner of the broad fascia of the thigh; 11 - two-headed m. Thigh; 12 - tail mm .; 13 - coccygeal gland; 14 - superficial chest m; 15 - mm. wing; 16 - oblique outer m. Abdomen; 17 - calf m.; 18 - long peroneal m.; 19 - semitendinosus m.; 20 - semi-membranous m.; 21 - internal oblique m. Abdomen; 22 - mm. anus and cloaca.

Pelvic limb muscles 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, the extensors and flexors are developed. Their tendons tend to ossify. 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. Chickens have a well-developed mechanism for sitting on a branch 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 attaches to the tendon of the scallop muscle, then passes to the lateral side of the leg, is fixed on the fibula, turns to the plantar surface and fuses with the tendons of the flexor of the fingers. This mechanism binds the joints so that when the knee is bent, the fingers are also bent.

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

Skeleton structure

At least an approximate understanding of how the chicken skeleton works will help the poultry farmer to conduct mandatory routine examinations of his livestock and diagnose various ailments in time. The skeleton of a chicken has this feature: many of the bones of the bird are hollow inside. This is due to the fact that the chicken can fly, although it does not often do it. The total bone weight of a domestic bird rarely exceeds 10% of its body weight. The second feature is that the chicken has no teeth; instead, it has a dense horny process - the beak.

The chicken skeleton is conventionally subdivided 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 vertebrae of 7, the caudal part includes 5-6 movable vertebrae. The thoracic region also has such a specific component as the keel. The forelegs of birds are better known to us as wings.

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

Laying hens are 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 the 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 in a cloaca. The beak is intended solely for swallowing food, nature did not endow the birds with teeth, since they would significantly weigh the bird's head. Precisely because the primary fermentation of feed does not occur in the oral cavity of chickens, they need 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 along 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, where strong acid and enzymes necessary for digestion are abundantly released. In addition, pebbles and sand can often be found in the stomach of a bird. Birds purposefully swallow such foreign objects. They become part of digestive system birds and help her grind roughage.

Digestive system: 1 - oral cavity, 2 - esophagus, 3 - goiter, 4 - glandular stomach, 5 - muscular stomach, 6 - duodenal intestine, 7 - pancreas, 8 - gallbladder, 9 - liver, 10 - intestine small, 11 - ileal intestine, 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 away" from it. Undigested food will form into feces in the large intestine, which ends in a cloaca. I must say that this is the only "way out" from the chicken body. The whole process of digestion in birds is very fast, coarse grains are digested for the longest time.

Respiratory system

The unusual structure of the respiratory system is due to the fact that birds need a very large amount of oxygen during flight. And, although the birds in our courtyard 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 flows into the nasal cavity and larynx, then 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 the organ of sound production. The bronchi extend beyond the lungs and communicate with multiple air sacs located in the bird's body. Air sacs are now only found in birds, presumably they were in dinosaurs, so birds are often credited with being related to extinct reptiles. Most of the air inhaled by the bird "settles" in the air sacs, about 75%.

Chicken lungs practically do not change their volume, they are not able to stretch as much as the lungs of mammals. 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 bags serve for thermoregulation and gas exchange.

Circulatory system

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

The systemic circulation begins with the left ventricle, from where blood from the aorta will flow 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 fast heart rates.

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

Allocation 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 absence 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 amount of feces in a chicken is much greater than in mammals. This provides the lightness of the body that birds need in flight.

Reproductive system

Chickens breed differently from us, our feathered friends are oviparous. In males, the reproductive organs are the testes located near the kidneys. Testes greatly increase in volume during bird breeding. The vas deferens depart from the testis, which end in a seminal vesicle - a receptacle for sperm. Chickens do not have an external genital organ; fertilization is carried out by contacting the cloaca of a rooster and a hen.

In the female, only one ovary is properly developed - the left one. It is also located near the kidney. The left oviduct departs from it, which, with an expanded funnel, opens into a coiled 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 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 and midbrain and the cerebellum. The cerebral hemispheres are small and have no convolutions. Perhaps that is why they often talk about “ chicken brains"As about something insignificant.

The cerebral hemispheres carry out orientation in space and the realization of the chicken's instincts. The cerebellum is responsible for the coordination of movements.

Chicken Opening Video

The autopsy of the chicken will complete our review!

When birds gained the ability to fly, their structure underwent noticeable changes in comparison with 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 came in their place.

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

Bird skeleton

The bird's skeleton is characterized by 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 intergrowth of a number of structures.

For convenience of description, the skeleton of birds is divided into the skeleton of the limbs of the axial skeleton. The latter includes the sternum, ribs, spine and skull, and the second consists of arcuate shoulder and pelvic girdles with the bones of the hind and front joint limbs attached to them.

The structure of the skull in birds

The bird's skull is characterized by huge eye sockets. Their size is so great that the cerebral box adjacent to them from behind is, as it were, pressed back by the eye sockets.

Bones that project very strongly forward form the toothless upper and lower jaws, which correspond to the upper and lower beak. Ear openings are located under the lower edge of the eye sockets and almost closely to them. Unlike the upper part of the jaw in humans, the bird's upper jaw is mobile, due to the fact that it has a special, hinged attachment to the cerebral box.

The spine of birds consists of many small bones called vertebrae, which are located one after another, from the base of the skull to the end of the tail. The cervical vertebrae are distinct, very mobile, and there are at least twice as many of them as in most mammals, including humans. This allows birds to tilt their head very strongly and turn it in almost any direction.

The vertebrae of the thoracic region are articulated with the ribs and in most cases are firmly adhered to each other. In the pelvic region, the vertebrae are fused into one long bone called the complex sacrum. These birds have an unusually hard back. The remaining caudal vertebrae are quite mobile, except for the last few, fused into a single bone called the pygostyle. In their shape, they resemble a plow share and are a skeletal support for long tail tail feathers.

Bird chest

The bird's heart and lungs are protected from the outside and surrounded by ribs and thoracic vertebrae. Fast-flying birds have an extremely wide sternum that grows into a keel. This ensures effective attachment of the main flight muscles. In most cases, the larger the keel, the stronger the flight. Birds that do not fly at all have no keel.

The shoulder girdle connecting the wings to the outer skeleton on each side is formed by three bones, which are arranged like a tripod. One leg of this structure (crow's bone - coracoid) rests against the sternum of the bird, the second bone, which is the scapula, lies on the ribs of the animal, and the third (clavicle) merges with the opposite clavicle into a single bone called the “fork”. The scapula and coracoid, where they converge, form the glenoid 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 those of the human hand. Just like in humans, the only bone in the upper limb is the humerus, which articulates at the elbow with the two bones (ulna and radius) of the forearm. Below begins the brush, many of the elements of which, unlike their human counterparts, are fused with each other or are completely lost. As a result, only two carpal bones remain, one buckle (a large metacarpal carpal bone) and four phalangeal bones, which correspond to three fingers.

A 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's brush includes fewer elements. The reason is also that the long bones of the bird's forearm and shoulder 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 large muscles are absent in it. Instead of muscles, the main movements of the wings are controlled by the tendons of the highly developed musculature of the sternum.

The flying feathers that extend 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 cover feathers, which smoothly, like tiles, lay 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 ischial bones, and the ilium is fused with the sacrum, which is complex in structure. This sophisticated design protects the kidneys from the outside while maintaining 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 acetabular cavity. The head of the femur rotates in it.

Bird legs arrangement

As in humans, the femur of birds is the core of the upper part of the lower limbs. In the knee joint, the shin joins this bone. But if in humans the tibia and tibia are part of the tibia, then in birds they are fused together, as well as with one bone of the tarsus or with several. Together, this element is called Tibiotarsus. As for the fibula, only a short, thin rudiment remained visible, which adjoins the tibiotarsus.

Bird feet device

In the intra-metatarsal (ankle) joint, the foot is attached to the tibiotarsus, which consists of one long bone, the bones of the fingers and the tarsus. The latter is formed by the elements of the metatarsus, which are spliced \u200b\u200btogether, as well as several tarsal lower bones.

Most birds have four fingers, each of which is attached to a tarsus and ends in a claw. The first finger in birds is turned back. The rest of the fingers are in most cases directed forward. Some species have a second or fourth finger facing back (like the first). It should be noted that in Swifts, the first finger is directed, like the rest of the fingers, 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, without resting their heel on the ground.

The muscular system in birds

The legs, wings, and other parts of the bird's body are propelled 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 providing flight are the pectoralis muscle and the supracoracoid muscle. Both muscles begin on the sternum. The largest muscle is the pectoralis. It pulls the wing downward causing the bird to move up and forward in the air. And the supracoracoid muscle raises the wing up, in the direction opposite to the work of the pectoral muscle, preparing it for the next swing. It must be said that in turkey and domestic chicken, these two muscles are considered "white meat", while the rest of the muscles are referred to as "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 movements of the feathers. There is smooth muscle in the eyes: thanks to it, the image is focused on the retina. Such musculature, in contrast to the striated musculature, is called involuntary musculature, since it works without volitional control.

The nervous system in birds

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

The most prominent part of the brain in birds is the cerebral hemispheres, which are the center in which higher nervous activity takes place. The surface of these hemispheres does not have any convolutions or grooves typical for many mammals, and its area is quite small, which coincides with the relatively low intelligence of the bulk 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 grooves. Its large size and structure correspond to the complex tasks 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 in birds is noticeably larger than in mammals of the same size. At the same time, it was noticed 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, a hummingbird has a heart weight of 2.75% of its entire body weight. This is necessary so that all perennial birds can ensure rapid blood circulation. The same applies to those species of birds that live at high altitudes or in cold areas. And, 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 stress. For example, the heart rate of a resting ostrich is about 70 beats / min, while in a hummingbird it rises to 615 beats / min during flight. However, excessive fright can scare the bird so much that the increased pressure can cause arteries to burst and the bird to die.

Like mammals, birds are warm-blooded animals, while the range of normal temperatures of their bodies is higher than that of humans and ranges from 37.7 to 43.5 degrees. Typically, avian blood contains more red blood cells than most mammals. Thanks to this, the bird's blood can carry more oxygen per unit of time, which is very important for flight.

The respiratory system in birds

In almost all birds, the nostrils lead to the nasal cavities at the base of the beak. But there are exceptions: gannets, cormorants and some other species of birds do not have nostrils and therefore have to breathe through their mouths. Air trapped in the nose or mouth moves to 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 getting into them.

Closer to the lungs, the trachea divides into two bronchi, which enter one into 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. Pair of special singing muscles are attached to them. When exhaled air from the lungs passes through the lower larynx, it vibrates the membranes, which produces sounds. Those birds, which 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 into thin tubes at the entrance to the lungs. The walls of these tubes are permeated with blood capillaries, which receive oxygen from the air and give back carbon dioxide to it. These tubes are directed into thin-walled air sacs that resemble soap bubbles not penetrated by capillaries. These bags are located outside the lungs - in the pelvis, shoulders, neck, around the digestive organs and the lower larynx, and even nestle in the large bones of the wings and legs.

When the bird inhales, air through the tubes enters these very bags, and when exhaling, it goes from the bags 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 bags moisturize the air and also regulate body temperature. This is achieved due to the fact that as a result of evaporation and radiation, the surrounding tissue can lose heat. As a result, the birds acquire the ability to sweat from the inside, which is a worthy compensation for the absence of sweat glands in birds. In addition, air sacs help to remove excess fluid from the body.

The device 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 to the opening of the cloaca. This tube performs many functions at once, taking in food, secreting juices with enzymes that break down food, absorbs substances, and also removes undigested food residues. However, despite the fact that in all birds the structure of the digestive system, as well as its functions, are the same, in some details there are differences that are associated with feeding habits, as well as with the diet of a particular group of birds.

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

The functions and shape of the tongue, as well as the beak of a bird, depend on what kind of life a particular species of bird leads. The tongue can be used both for holding food in the mouth and for manipulating it in the oral cavity, as well as for determining the taste of food and feeling it.

Hummingbirds and woodpeckers have a very long tongue that they can stick out far beyond their beak. In some woodpeckers, at the end of the tongue there are notches directed backwards, thanks to which the bird can pull insects and their larvae located in the bark to the surface. But the tongue, as a rule, is forked at the end and rolled into a tube, which helps to suck the nectar from the flowers.

In pheasants, grouses and turkeys, as well as in some other birds, part of the esophagus is constantly dilated (called goiter) and is used to store food. In many birds, the esophagus is quite extensible and can hold a significant amount of food for some time even before it enters the stomach.

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

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

The genitourinary system in birds

The genitourinary complex consists of the excretory and reproductive systems, which are very closely related to each other. The excretory system functions continuously, while the second 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 named, which remove waste from the blood and form urine. Birds do not have a bladder, so urine through the ureters enters the cloaca, where the bulk of the water is again absorbed into the body. The remaining porridge-like white residue, together with the dark-colored feces from the large intestine, is thrown out.

Reproductive system in birds

This system consists of the gonads (gonads) and the tubes that extend from them. Male gonads are represented by a pair of testes, in which gametes (male reproductive cells) are formed - spermatozoa. The testes are either elliptical or oval in shape, with the left testes usually larger than the right. The testes are found in a body cavity near the anterior end of each kidney. With the approach of the mating season, the pituitary hormones, due to their stimulating effect, enlarge the testes several hundred times. Sperm from each testis enter the seminal vesicle through the thin and tortuous vas deferens. It is there that they accumulate, persisting 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) form the eggs (female gametes). The bulk has only one (left) ovary. The egg cell, when compared with a microscopic sperm, is huge. In terms of mass, its main part is the yolk, which is a nutritious material for the embryo that began to develop after fertilization. The ovum from the ovary enters the oviduct, the muscles of which push the ovum past all kinds of glandular areas in the walls of the oviduct. With their help, the yolk is surrounded by protein, which are under the shell and the shell consists mostly of calcium. At the end, pigments are added that color the shell in one color or another. It takes about a day for the egg to develop a ready-to-lay egg.

Internal fertilization is characteristic of birds. During copulation, spermatozoa enter the female's cloaca and then move up the oviduct. The female and male gametes (that is, the actual fertilization) occurs at the upper end of the oviduct even before the ovum is covered with protein, shell membranes and shells.

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