The digestive system of a bird. Internal structure of birds

The most important functions of the intake of substances, their transformation and excretion of undigested residues from the body is performed by the digestive system. Birds, being animals adapted to flight, possess certain features of the internal structure. First of all, they are aimed at reducing their body weight. The digestive system is no exception.

Animal Digestive System

All chordates, including birds, have a similar structure of the digestive system. It begins with a mouth. Further through the pharynx, the food enters the esophagus-the tube that leads into the stomach. This part of the digestive system is an extension in which the food is sufficiently long. The final absorption of nutrients occurs in the small intestine, and the elimination of undigested food remains in the final section of the tract. It is called the large intestine, opening outward with a cloaca or anal opening.

Features of the digestive system of birds are in the presence of goiter - expansion of the esophagus and a decrease in the length of the intestine. These features of the structure contribute to more intensive digestion of food and reduce body weight of birds.

The same can be said about other organ systems?

Internal structure of birds (table).

System of organs	Features of the structure
Respiratory	Presented by the respiratory tract (nasal cavity, larynx, trachea, bronchi), lungs and air sacs
Circulatory	Four-chambered heart (two auricles and two ventricles) and a closed system of blood vessels. Birds have two circles of circulation: large and small. Due to this, the venous and arterial blood does not mix, and the birds are warm-blooded animals. Thus, their body temperature does not depend on the ambient temperature.
Excretory	It consists of paired kidneys and ureters, the ducts of which open into the cloaca.
Nervous	The spinal cord and the brain, from which the cerebellum is most developed.
Sexual	Birds are dioecious animals. The reproductive system is represented by the sex glands: the testes in males and the unpaired ovary in females, which also serves as a condition for reducing their mass.

What feeds birds

The structure that the digestive system of a bird has, its features and differences, is primarily determined by the nature of the food. Urban dwellers eat insects, seeds and the remnants of human food.

Taste preferences of birds are quite diverse. Seagulls drink salt water, filtering it through the tonsils.

A poisonous bird is a flycatcher also because of the peculiarities of food. She uses beetles. Their poison penetrates the skin and feathers of the bird. Although the flytrap itself has a stable immunity to its action. A person can get a burn by touching it. But very small animals are killed by the harmful effect of the toxins of the flytrap.

Feathered, who live in natural conditions, eat tasty fruits, small vertebrates and even carrion. For this they have all the devices.

Beak

Birds do not have teeth. But they can easily cope with hard nuts, and with small seeds. After all, the function of the teeth is initially performed by the beak. With its help birds chop, crush or tear food. The beak consists of a solid horn-like substance capable of withstanding a sufficiently large weight and prolonged loads. For example, a forest woodpecker can make a hole in the bark of trees up to 10 cm in depth to feast on insect larvae.

The shape and size of the beak depends on what the birds eat.

For example, predators have a large curved beak, with which they can easily grab and tear the victim. Peregrine Falcon attacks even large foxes and wolves. Forest birds, extracting insects from the bark of trees, like a chisel, make holes in it.

To get food helps and the tongue, located in the oral cavity. It has special horny papillae, which help to keep food in the mouth.

The digestive system of the bird continues with a pharynx, with the help of which already partially processed food moves along the tract.

Esophagus and goiter

The esophagus of the bird has an unusual structure. It's not just a tube that leads into the stomach. It forms an extension called goitre. It is here that food is delayed for a certain time and is chemically treated with saliva. And seagulls and pelicans carry the chickens to the goiter from the place of feeding into the nests.

What is the bird's milk

The name of this delicious dessert is familiar to everyone from childhood. It got its name due to the external resemblance to the substance, which only the birds can distinguish.

Some birds in the specialized glands of goiter form a nutritious foamy mass. This valuable product they use to feed the chicks.

Bird's milk has nothing to do with the milk of animals. It is not at all liquid, but it seems like a whipped cottage cheese mass. But it also contains many valuable organic substances and vitamins that can provide the newborn with everything you need.

In penguins, bird's milk is formed in the stomach, and not in the esophagus, it is most rich in fats. This substance is necessary for the development of chicks in severe northern conditions. And adult penguins use the fat layer not only to warm the body, but also as a store of food and energy. Hatching the chicks for several months, the males do not leave the masonry. In this state, they simply can not get food and maintain viability through subcutaneous stores.

Features of the structure of the stomach of birds

The stomach of birds also has characteristic features. It consists of two parts.

The departments of the stomach are called glandular and muscular. In the first food is processed by gastric juice, i.e. Here its chemical treatment continues. The surface of the muscular part is covered with a film of keratinized substance. With its help, the food is rubbed up to a mushy state.

Surely many have seen how birds peck small pebbles. They do this not because they do not know about their taste. Getting into the muscular part of the intestine, the stones contribute to the mechanical grinding of coarse food. Thus, the absence of teeth in birds is compensated.

Intestines

From the stomach, the processed food enters the small intestine, into which the ducts of the liver and pancreas open. In this part of the digestive system, the food is finally digested and absorbed into the blood.

Outward intestine opens cloaca. It is a hole through which the undigested remnants of food, the products of the functioning of the sexual and excretory systems, are removed.

The peculiarity of the structure of the intestine is its short length. It depends on the nature of the food. For example, in birds that prefer vegetable food, the intestine is 8 times as long as the body. And insectivorous representatives of birds - only 4.

By the way, the most gluttonous bird is considered to be the record holder of the smallest sizes. Guessed? Well, of course, it's a hummingbird. For a day, she is able to use flower pollen, whose weight is 2 times greater than her own weight.

A wren in one day brings the chicks up to 500 caterpillars and insects. Here is the appetite!

And vultures are winners among the most greedy and insatiable creatures. With a large amount of food, they are so full that it is simply impossible to fly. The griffins solve this problem in a natural way: they wait for the body weight to decrease.

Birds digest food intensively, quickly emptying the intestines. This helps to reduce their body weight and provide the body with the right amount of energy. A common sparrow is able to digest a caterpillar for 15 minutes, and grains - for 3 hours. That's why most of their life birds spend in search of food.

Digestive glands

Saliva, pancreas and liver are the list of digestive glands that birds have. They release biologically active substances - enzymes. They accelerate the digestion process, splitting complex carbohydrates to monosaccharides, proteins to amino acids, lipids to glycerol and fatty acids. It is in this form that organic substances can be absorbed by the body.

Features of the process of digestion of birds

The internal structure of birds (the table is presented in the article) indicates that all the features of their anatomical organization are aimed at adapting to the flight. This also applies to the digestive system.

Instead of cheeks and lips, birds have a beak, through which food is captured and held. The oral cavity has a hard palate. It is covered by the mucosa, on which are located special papillae cone-shaped. With their help, the food moves to the esophagus. To prevent food from getting into the nasal cavity, the palatine cleft is already made by the non-panicleous muscles.

The departments of the stomach, performing various functions, contribute to intensive processing of food. The intestine consists of two sections - thin and thick.

The digestive system of the bird provides all the processes of the life of the birds. And the peculiarities of its structure determine the ability of these amazing animals to fly.