Diseases of the respiratory system If the dog shows signs of it, it may indicate any infection or decreased immunity. The only exception is upper respiratory tract diseases and bronchopneumonia. In most cases, symptoms with

Repeat the general characterization and classification of the Chordovye type.

To study the aromorphosis of the Bird class. Write it in the notebook.

To study the structure of birds. Make a note in the notebook.

Consider stuffed birds of different species.

To study the external and internal structure of birds by the example of the Dove (opening the dove).

In the album, perform 7 drawings, indicated in printed methodologies V (red tick). In the electronic methodology, the drawings to be performed in the album are presented at the very end of the text.

In the notebook, write down and learn the classification of modern birds.

In the notebook draw and fill the table 1.

Table 1. Structure of the bird's egg.

In the notebook draw and fill in the table 2.

Table 2. Variety of birds.

Know the answers to control questions   Topics:

General characteristics of the Chord type. Classification of the Chordovye type.

Features of the organization of birds.

Systematic position, lifestyle, body structure, reproduction, meaning in nature and for the person of the Dove.

General characteristics of birds

In modern systematics of animals Birds  (Aves) is a class in the Chordata type of the vertebrate subtype.

Basic aromorphosis(aromorphoses are major evolutionary changes leading to a general complication of the structure and organization of the organism) Birds are the following:

1. the appearance of a four-chambered heart;

   complete separation of arterial and venous blood flow;

   perfection of thermoregulation;

   formation of spongy lungs;

   progressive development of the nervous system;

   ability to fly;

   adaptive behavior.

Birds- warm-blooded animals capable of flying. They settled around the globe, settled a variety of places, and also mastered the air habitat. Currently, more than 8 thousand species are known, united in 35-40 detachments.

Birds arose early in the Jurassic period (195 million years ago), and perhaps a little earlier - even in the Triassic of the Mesozoic era (230 million years ago), from ancient reptiles, from which dinosaurs also originated.

Structure of birds

The structure of birds is considered in the example Blue Dove  (type Chordovye, subtype Vertebral, class Birds, order Goluboobraznye). Blue dove  lives in forests, mountains and cities, everywhere. Pigeons nest on trees, rocks, in buildings, hollows. Live in pairs, colonies. In laying 2 eggs. Eggs are hatching both the female and the male. Hatched chicks are naked, blind and require a long-term care of their parents. Both parents care about the chicks, who first feed them with "goat's milk," and then regurgitate their partially digested food. To feed the grain already fully fledged chicks, leaving the nest. Dove gray - the progenitor of numerous breeds of decorative and postal pigeons.

So, the body of streamlined birds consists of a small head, neck, trunk and tail. The forelimbs are the wings, the hind legs are the legs. On the head there is a beak consisting of a suprug and a hook. The beak is covered with a horny cover. At the base of the supraclue lie the holes of the nostrils, a piece of soft naked skin, a waxen, adjoins them. On the sides of the head are large eyes, protected by upper, lower eyelids and a blinking membrane. Behind the eyes are external auditory orifices. The neck is long and movable.

Cover.Skin is thin, dry. The only skin gland located at the base of the tail (coccygeal), secretes a fat-like secret for lubrication

General characteristics of birds

feathers (elasticity, water repellent property). The skin is covered with feathers (Figure 1, 2).

The feather consists of an arm, a rod and a fan (Figure 2). The plague was formed by the first and second order beards, which are connected by hooks, forming a closed plate. Contour feathers on the tail are called helms, on wings - flight, and on the ventral and dorsal sides of the body - are covered. The plane of the wing is formed by two rows of contour, fly feathers, covered with overlapping feathers (streamlined body shape). Under feathers there are down feathers. Change of the feather cover is accompanied by seasonal moulting. Its functions: the acquisition of seasonal coloring, demonstration coloring during the mating season and thermoregulation. The areas covered with contour feathers alternate with areas of bare skin. By giving away excess heat, non-regenerated areas protect the body from overheating. On the lower part (forge), the fingers are covered with horny shields.

The characteristics of feathers are discussed in Table 1.

Fig. 1. Types of feathers.

1 - contour feather; 2 - side lateral feather wood grouse; 3 - down feather; 4 - threadlike feather; 5 - seta; 6 - actually down.

General characteristics of birds

Fig. 2. The structure of the pen.

1 - fan; 2-barrel; 3 - feather down; 4 - the upper hole; 5 - clear; 6 - lower opening.

Table 1. Types of feathers in birds.

General characteristics of birds

Skeletonhas structural features in connection with the adaptation to flight and walking on land only on the hind limbs. Lightness of the skeleton is provided by the pneumaticity of the bones (the presence of air cavities in the tubular bones). The strength of the skeleton is ensured by the fusion of individual bones (sternum, complex sacrum).

The skeleton consists of the axial skeleton (spine), the skeleton of the head (skull) and the skeleton of the limbs. The structure of the skeleton of the bird is shown in Figure 3.

The spine is divided into five divisions: cervicalincludes 14 vertically connected vertebrae. Thoracicconsists of five vertebrae, fused together. Together with the ribs and the sternum, they form a thorax. On the sternum there is an outgrowth - a keel, which increases the area of ​​attachment of pectoral muscles. Lumbaris formed by six vertebrae, merged into one continuous bone plate. Sacralconsists of two vertebrae. The last thoracic vertebra, all lumbar, sacral and anterior caudal (five) fuse together into a single complex sacrum. Tailconsists of 15 vertebrae. The anterior five vertebrae are part of a complex sacrum, the middle six remain free, and the four posterior vertebrae merge to form the coccygeal bone (pigostyle) to which the bases of the steering feathers are attached.

Skullcoarse, articulate with the spine with a single condyle. It consists of a large cerebral part and jaws, covered with horny covers, forming a beak (without teeth). The skull has a narrow base and very close walls of huge eye sockets. There is a fusion of bones with the disappearance of the seams of the skull (strength, lightness of construction).

Skeleton of the extremitiesincludes belts and a skeleton of free extremities. Shoulder girdleconsists of three pairs of bones: scapula, collarbone and crow's bones. Both clavicles become fused into a fork, giving the waist elasticity. Pelvic girdledurable, stable. Pairwise pelvic bones are fused with the lumbar and sacral parts of the spine and the first caudal vertebrae.

Skeleton of free extremities:the forelimbs are transformed into wings and consist of the shoulder, forearm, and hand. The bones of the wrist and pastern merge, forming a buckle. Of the fingers, only three are retained - the second, third and fourth, while the third finger has two phalanges, and the second and the fourth finger - one by one. The hind legs serve for movement on the ground and consist of the hip, the leg (the tibia is rudimentary and grows to the large tibia) and the forelock (fused bones of the tarsus and metatarsus). Fingers four, three of them are directed forward, one - back.

General characteristics of birds

Fig. 3. The skeleton of a dove (diagram).

1 - the upper jaw; 2 - the lower jaw; 3 - cervical vertebrae; 4 - the shoulder; 5 - thoracic vertebrae; 6 - clavicle; 7 - crow's bone; 8 - sternum; 9 - keel; 10 - the lower thigh; 11 - trowel; 12 - thigh; 13 - the pelvis; 14 - the coccygeal bone; 15 - caudal vertebrae; 16 - ribs; 17 - forearm; 18 - brush; 19 - scapula; 20 - the skull; 21 - toes of the foot.

General characteristics of birds

Fig. 4. The internal structure of the bird (pigeon).

1 - trachea, 2 - goiter, 3 - singing (lower) larynx, 4 - jugular vein, 5 - ventricles of the heart, 6 - right atrium, 7 - aorta, 8 - unnamed artery, 9 - pulmonary arteries, 10 - lungs, 11 - liver, 12 - small intestine, 13 - pancreas, 14 - large intestine, 15 - caecum, 16 - cloaca, 17 - tissue bag, 18 - ureter, 19 - kidney, 20 - testis, 21 - muscular stomach.

General characteristics of birds

The internal structure of the bird is shown in Figure 4.

Muscular systemhighly developed and differentiated. The most developed muscles of the breast, providing the movement of the wings. Paired large pectoral, attached to the sternum and its keel, serve to lower the wing, subclavian muscles - to lift the wing. Long neck muscles provide complex head movements. Strongly developed muscles of the hind limbs are designed for movement on the ground.

Nervous systemconsists of a spinal cord and a brain with nerves running away from them. The brain is represented by the following departments:

1. The forebrainhas developed large hemispheres. Their surface contains a cluster of nerve cells that form the archipallium. However, most of the forebrain is formed by striped bodies. There is no furrows and no crinkles. Hemispheres regulate complex forms of behavior of birds, visual lobes are developed strongly, and olfactory lobes are weak.

2. The Intermediate Brainweakly developed. On the upper side there is an epiphysis, and at the bottom, behind the cross of the optic nerves, is a large pituitary gland.

3. Middle Brainhas well developed visual hillocks.

4. Cerebellumis well developed in connection with coordination of movements and balance during the flight. It consists of an average lobe - a worm and two lateral protrusions. Behind covers the middle brain and part of the medulla oblongata.

5. Medullapasses into the spinal cord.

From the brain leaves 12 pairs of cranial nerves.

Spinal cordhas a thickening in the shoulder and lumbar regions, where nerves from the anterior and posterior extremities leave from it, forming the humeral and pelvic plexus.

Sense organs.Leading are sight and hearing. Body of taste- gustatory bulbs in the pharynx. Olfactory organweakly developed. Body of sightvery well developed. Eyeballs are large, located on the sides of the head. The field of view of each eye is 150 °, and the field of binocular vision is 30-50 °. Visual acuity is very high. The image on the retina is large, which makes it possible to distinguish the details of the object. The retina has a high density of photoreceptors, birds distinguish colors and shades. Accommodation (double) is carried out by changing the shape of the lens (under the action of the ciliary muscle) and simultaneous movement relative to the retina. In the field of the blind spot there is a vascular formation - a crest, which is a source of nutrients and oxygen. The mechanical strength of the eyes is provided by the thickening of the sclera and the appearance of bone plates in it. Eyelids are well developed. There is a blinking membrane (third eyelid). The organ of hearingdeveloped

General characteristics of birds

oK. It consists of the inner and middle ear. In the inner ear, the outgrowth of the round sac grows longer and the number of sensory cells increases. In the middle ear, the sizes of the tympanic cavity increase, the shape of one auditory ossicle - stapes becomes more complicated, which increases its mobility. Increase the size of the tympanic membrane. Eustachian tubes open into the pharynx with one common opening. Appearance of the rudiments of the outer ear, and there is an auditory canal, ending with the eardrum. Organs of skin sensation- accumulation of sensitive cells that react to changes in the position of the feathers. Thermal Detectorsrecord changes in body temperature, consist of a cluster of sensitive cells, braided with nerve endings.

Digestive systemis associated with the features of life processes. The warm-bloodedness and high mobility of birds require significant amounts of food and its rapid assimilation. Food in the gastrointestinal tract is quickly digested due to the activity of digestive enzymes and an increase in the intestinal absorption surface. Horny edges of the jaw form a beak, which serves to seize food. No teeth. The tongue is muscular, conical, and has keratinous spines for retaining food. Protocols of the salivary glands with digestive enzymes. The pharynx has a guttural cleft with a respiratory system. The esophagus is long and easily extensible, the lower part of it forms a temporary receptacle of food - goiter. The stomach is divided into two sections: glandular, with thick walls that secrete digestive juices; muscular, with an internal dense horny surface, where food moistened with digestive enzymes, is mechanically treated with muscle contractions and is crushed by stones (gastrolites).

The intestine is long, differentiated into the duodenum (opening the ducts of the liver and pancreas), the small intestine, twin blind and short large intestine, ending in a cloaca. The rectum is very short, and the undigested remnants of food, not accumulating, are rapidly excreted. On the dorsal side of the cloaca there is a blind outgrowth - a factory bag carrying out the function of an endocrine gland and participating in the immune defense of the body. The liver is large, bilobate. There is no gall bladder in the pigeon.

Respiratory systemconsists of a complex system of airways and lungs. Airways include the nostrils, the nasal cavity, the nasopharynx, the larynx and the long trachea. In the place of branching of the trachea to the bronchi there is an inferior larynx, peculiar only to birds. In it are located vocal cords, which, when the air passes, vibrate and make sounds. The variety of sounds published is controlled by the contraction of specific singing muscles. Lungs - dense spongy bodies, slightly elongated, with a small volume. They consist of branched bronchial tubes. The main bronchus enters the lung and gives 15-20 branches (secondary bronchi), connected by a parabronchia with numerous outgrowths (bronchioles), braided by a network of blood vessels

General characteristics of birds

capillaries (gas exchange takes place). Part of the bronchial branches (4-5 bronchi) extend beyond the lungs and form thin-walled extensions - air sacs located between internal organs. By volume, they are about 10 times the volume of the lungs. There are paired air bags (cervical, antero-thoracic, hind-ham and abdominal) and unpaired air sacs (interclavicular). The outflow of air bags penetrates the cavities of large bones. The importance of air bags: cooling and relief of the body, "pumps", pumping air into poorly dilated lungs (gas exchange in bags does not occur). The mechanism of breathing thoracic. With the expansion of the chest, an inhalation occurs, with the relaxation of the pectoral muscles and the narrowing of the chest cavity - exhalation. Unlike all terrestrial vertebrates, birds are saturated with oxygen through the lungs, both on inhalation and exhalation (the so-called double respiration).

Circulatory systemclosed, has two circles of circulation. The heart is four-chambered (the right half contains venous blood, the left half - arterial blood), so the arterial and venous blood is completely separated, which ensures a high intensity of metabolism (warm-blooded animals). From the heart there are two independent vessels: the pulmonary trunk (carries venous blood) and the right arch of the aorta (arterial blood).

Small circle of blood circulation.From the right ventricle the pulmonary trunk leaves, which when exiting the heart is divided into the right and left pulmonary arteries. In the lungs, gas exchange takes place, and oxygen-enriched arterial blood flows into the left atrium along the right and left pulmonary veins.

Great circle of blood circulation.From the left ventricle, the right arch of the aorta departs, which when exiting from the heart is divided into two vessels: the right and left anonymous arteries, each branching into the common carotid and subclavian arteries (humerus and thoracic). The right aortic arch curves around the heart and forms the dorsal aorta. All the organs of the body are supplied with arterial blood. Venous blood from the back of the body is collected along the inferior vena cava and flows into the right atrium, previously cleared through the portal system of the liver and kidneys. Venous blood from the anterior part of the body gathers into the forward hollow veins that flow into the right atrium. The heart is large in comparison with the size of the body. A high rate of blood circulation through the vessels is provided by a high heart rate.

Excretory systemis represented by pelvic kidneys (metanephros, secondary kidney). The relative size of the kidneys in birds is large and is in direct connection with a very intense total metabolism. From the kidneys depart ureters, flowing into the cloaca. The final product of metabolism is uric acid. Urine passes through the excretory pathway quickly due to poor solubility of uric acid, the possibility of plugging the urinary salts of the conductive pathways and is excreted as white crystals along with the droppings. With this is the lack of

General characteristics of birds

birds of the bladder. The loss of water during urination in birds is small, since in the cloaca the water is back-sucked.

Sexual system.Dioecious. The sexual glands are paired. In males, testicles of the bean-shaped form suspended on the mesentery are located above the upper part of the kidneys. The size of the testes varies by season. By the time of reproduction, the testes are enlarged 1500 times. To the inner edges of the testes join the weakly appendages, from which the vas deferens, located parallel to the ureters and flow into the cloaca. In some species, the vas deferens form an expansion - seminal vesicles (a seed reservoir) before entering the cloaca. There is no copulatory organ. Fertilization is internal (in the upper parts of the oviduct), by approaching the holes of the cloaca of the female and male. In females, the reproductive system consists of the left ovary and the left oviduct, which opens into the cloaca. The reason for the reduction of the right half is apparently related to the deposition of relatively large eggs with a hard shell. Ovary granular, irregular in shape, located in front of the left kidney. Its value varies depending on the maturity (size) of the eggs being formed. The oviduct has the appearance of a long tube, one end of which opens into the cloaca and the other into the body cavity. The initial section of the oviduct is rich in glands secreting the protein, which covers the passing egg with a thick layer. In the next section, the egg is covered with under shells. In the uterus, a calcareous egg shell is formed and the staining of the supracerebral shell is formed. The last section of the oviduct (vagina) is short and has considerable muscle, from it the egg leaves the cloaca and further outwards. The whole period of passage of the egg along the oviduct takes 41 hours.

Birds are amniotes, i.e. vertebrates, whose embryos have embryonic membranes, which ensure the development of the embryo in the terrestrial-air environment.

Developmentin birds - direct. The dove's female lays two eggs in the nest. According to the type of development, pigeons refer to chicks (nesting) birds. Development of the embryo begins as a result of warming the egg (incubating 16-19 days). As the development develops, the feather cover, the beak, and the tail disappears. Before hatching the chick with its beak breaks the inner shells of the egg and breathes lightly in the air chamber. Then, with the tubercle on the beak, the chick breaks the eggshell and exits it. Hatched chicks are naked, blind and require a long-term care of their parents. Both parents care about the chicks, who first feed them with "goat's milk," and then regurgitate their partially digested food. To feed the grain already fully fledged chicks, leaving the nest. The structure of the bird's egg is presented in Table 2. The differences between the chicks and brood chicks are described in Table 3.

Seasonal phenomena in the life of birds.All birds can be divided into migratory, nomadic and sedentary. To migratory birds (ducks, geese, swallows) are species,

General characteristics of birds

which migrate to significant distances from the nesting sites. Nomadic birds (woodpeckers, titmice, snegiri) do not make regular flights in strictly defined directions, they hibernate near nesting places. Settled birds (blue dove, sparrows, jackdaws) migrate within the same area where they reproduce.

Ecology of birds.Birds are adapted to different habitats, which is the reason for the emergence among them of ecological groups (Table 4). Each group is tied to their habitats, uses their own food and has certain adaptations to their production.

Features of adaptation of birds to flight:the transformation of the forelimbs in wings;streamlined body, covered feathers;sternum formation in the form of keel,with a powerful musculature, control wings; double breath,providing an intensive metabolism; light skeleton(hollow bones); weight lossdue to the lack of a bladder, one ovary, teeth, rectum, copulatory organ; Availability high visual acuityand progressive development of the brain, in particular the cerebellum.

Table 2. Structure of the bird's egg.

General characteristics of birds

Table 2. (ending)

General characteristics of birds

Table 3. Types of development of chicks.

Table 4. Ecological groups of birds.

General characteristics of birds

Table 4. (continued)

General characteristics of birds

Table 4 (ending)

General characteristics. Birds arose in the Jurassic period and descended from non-specialized reptiles, who led a climbing lifestyle.

Occurrencebirds was accompanied by the following aromorphoses: 1. Progressive development of the nervous system (development of the cerebral cortex, cerebellum, the emergence of a thermoregulatory center). 2. The appearance of a four-chambered heart and a complete separation of the circles of the circulation. 3. Formation of spongy lungs. 4. The emergence of warm-bloodedness (homeothermia) as a result of progressive changes in the structure of the cardiovascular, respiratory and nervous systems.

Modern birds are represented by more than 8 thousand species, which are united in 35-40 orders, making four subclasses.

The structure of the body. The body is divided into head, neck, trunk and tail. The forelimbs are the wings, the hind legs are the legs. On the head there is a beak consisting of a suprug and a hook. The legs are four-fingered.

Cover. The skin is dry, without glands, covered with down and feathers (down and contour). Contour feathers of two types: mahovye (on wings) and steering (tail blades). The contour feather consists of an eye, a rod and a fan, which is formed by a dense network of beards of the 1st and 2nd (with hooks) orders. Down feathers, located under the contour, do not have fringes of the second order, so they are loose. The oil gland secretes an oily liquid, which the bird lubricates the feathers.

Skeleton. It consists of a skull, a spine, a belt of anterior and hind limbs, and free limbs. The skull includes a skull, eye sockets, upper and lower jaws (the base of the beak). The spine is divided into five sections: cervical (11 vertically connected vertebrae), thoracic, lumbar, sacral and caudal, connected immobile. The thorax is formed by five pairs of ribs, consisting of two parts, articulated movably. The sternum from below has a high crest - keel. The belt of the forelimbs is represented by paired bones - shoulder blades, collarbones and crow's bones. Clavicles form a fork. The skeleton of the wing consists of a humerus, an ulna and a radial bones, bones of a three-fingered brush. The bones of the hind limb are paired pelvic, fused with the lumbar and sacral parts of the spine and the first caudal vertebrae. The leg consists of the femur, fused large and small tibia bones, forelock (fused bones of the foot) and four fingers; the bones are hollow.

Muscles.Paired large pectoral, attached to the sternum and its keel, serve to lower the wing, subclavian muscles - to lift the wing. Well developed muscles of the legs, neck, intercostal.

Digestive system. The horn edges of the jaw form a beak, which serves to grasp and crush food. Oral cavity (with tongue), pharynx, esophagus, goiter, stomach (glandular and muscular), small intestine (liver, pancreas), large intestine (short), cloaca. Litter is a mixture of stool and urine.

Respiratory system. Nostrils, nasal cavity, larynx, trachea (voice apparatus), two light (spongy), air sacs. Breath is double. Gas exchange during inspiration and exhalation is carried out in the lungs.

Circulatory system. The heart is four-chambered, consisting of the left and right atriums and left and right ventricles. The left half contains arterial blood, the right one - the venous blood. Two circles of blood circulation, completely isolated from each other, as a result of which the blood does not mix. A large circle starts from the left ventricle and ends in the right atrium, a small circle (pulmonary) begins in the right ventricle and ends in the left atrium. Blood vessels of the great circle of blood circulation: aorta (right arch), arteries, capillaries, veins; small - pulmonary artery, capillaries, pulmonary vein.

Excretory system. Pelvic kidney, ureter, cloaca. There is no urinary bladder. Urine is very high concentration, since the metabolism is enhanced. Urine is excreted along with feces (litter).

Nervous system. It is represented by the brain and spinal cord and nerves leaving them. In the brain, the foremost hemispheres of the forebrain and the cerebellum are most developed. Conditioned reflexes.

Sense organs.Eyes with a wide field of view and high sharpness. The organs of hearing are internal (auditory snail and organ of balance) and middle ear (one auditory ossicle). The hearing is very subtle. The sense of smell is poorly developed.

Reproduction.In females only one left ovary and oviduct, in males paired bean-shaped testes, vas deferens and seminal vesicle in cloaca. There are no external genital organs: spermatozoa pass from the male cloaca to the cloaca of the female when they come into contact. Fertilization is carried out in the oviduct, after which the egg grows in size, covered with membranes (vitelline, albumen, two saccule and calcareous shell) and in the form of an egg goes into the cloaca.

Development begins only as a result of the warming of the egg (incubation). As the development develops, the feather cover, the beak. In the beak, the chick breaks through the shells of the egg and for the first time breathes light in the air chamber. Squeaking of the chick is the beginning of pulmonary respiration. Type of development - chicks (nesting).

Adaptationsto flight: 1.Transformation of the forelimbs into wings. 2. The feather cover. 3. Changes in the skeleton: a) fused in all parts except the cervical spine; b) the formation of the sternum of the sternum - keel, as a place for the attachment of muscles; c) hollow, thin-walled bones. 4. Development of thoracic-flying musculature. 5. Double breath, which ensures oxygenation of the blood by inhalation and exhalation. 6. Transformations aimed at facilitating the body in flight: a) the replacement of the jaws carrying the teeth, on an easy horny beak; b) absence of one of the ovaries; c) reduction of the posterior part of the intestine.

Representatives: ratites - running (ostriches); floating (penguins); kiledgrass (chicken, passerine, stork-like, anseriform, doves and many others).

Dove breathing organs provide gas exchange, thermoregulation, preserve acid-base and water balance. During breathing, moisture is released from the body, heat exchange occurs, and, consequently, nutrient breakdown.

Doves have a very complex structure of the respiratory system. There are many organs in it.

Air bags fill the space between the organs, communicating with other air bags. This system connects with each other and the organs of all other systems. Fill all the gaps in the body cavity, which protects the body from injuries.

The pigeon is adapted to long flights precisely due to this complex structure. The main components are the nasal cavity, upper larynx, trachea, lower larynx, bronchi, lungs and a system of branched air sacs.

They are best developed trachea, which is surrounded by cartilaginous arcs, not allowing it to shrink. And the respiratory gap is on the contrary narrow. The trachea branches into two bronchi. Bronchi also branch further into smaller ones, and so on, passing into the alveoli. At the ends of these branches, air bags are located, which are filled with air. They participate in the act of breathing and, thanks to their work, the bird acquires the ability to receive the required amount of oxygen in the shortest possible time, which is so convenient for the flight.

During the flight, the pigeon's breathing is not so intense, because it has the ability to draw oxygen, which is necessary for chemical processes in the body, from air sacs. They also perform the basic function of the body. And also soften the contact of the organs in the body cavity. At high loads, shocks or impacts a certain protective function is triggered.

Respiratory organs of pigeons are difficult to arrange in order to be able to rapidly and quickly absorb oxygen. This is necessary for a lot of muscle work. Pigeon - the bird is quite active, constantly in motion. It is worth noting that most of them live in cities. And the wings work quickly, sharply and very often.

In cities where the air is polluted and also the increased content of vapors and smog, even a complexly arranged respiratory system of the dove may fail. When the pigeons begin to catch their breath, they open their beaks wider and draw their wings back.

Air sacs perform one of the main roles. They replace the lungs, which are poorly developed in the pigeon.

The number of exhalations and breaths made by a dove in a minute is 17-37. Of course, this depends on his state of rest or wakefulness. But, as noted, the respiratory system of such a complex structure raises the birds one more step to the top.