Double Breath of Birds: Features of Gas Exchange

The respiratory system of birds is unique, it is adapted to regular flights. The best gas exchange in the body of birds is promoted by the double breath formed as a result of evolutionary transformations.

Upper respiratory tract

The path of air in the body of birds begins with a laryngeal slit through which it enters the trachea. Part of it, located on top - the larynx. It is called the upper, it does not play any role in sound formation. The voice of birds arises in the lower larynx, which is exclusively in birds. It is located where the trachea divides into two bronchi, and is an extension that is supported by rings of bones.

Inside the larynx there are attached vocal membranes attached to the walls. Under the influence of the singing muscles, they change the configuration, which leads to a great variety of published sounds. Internal vocal membranes are located below the place where the trachea is divided.

The upper respiratory tract is important for regulating body temperature. The heat leads to the fact that the bird breathes often and is shallow. The blood vessels located in the mouth and throat expand. As a result, the body of the bird cools, giving off the heat to the exhaled air.

Light and air bags

The structure of light birds is different from amphibians and reptiles, in which they resemble empty bags. In feathered fauna this organ is attached to the posterior part of the thorax. In composition it resembles a dense sponge. Branched bronchi have lintels - parabronchia with a large number of dead-end channels (bronchioles), which are braided by a dense network of capillaries.

Some bronchi after branching pass into large air sacs with thin walls. Their volume is much larger than that of the lungs. Birds have several air bags:

• 2 cervical,
• Interclavicular,
• 4-6 nursing,
• 2 abdominal.

Channels go under the skin and connect with pneumatic bones.

Double breath exists precisely due to air bags. With their help during the flight, the mechanism of breathing is determined.

Double Breath

The resting bird that sits carries out the renewal of air in the lungs by working the muscles. When the sternum is lowered, the oxygen-rich gas is sucked into the respiratory organ. The reverse movement of muscles pushes outward. Lungs also help pump oxygen.

The bird that walks or climbs, connects to the air bags located in the peritoneum. They put pressure on the upper parts of the legs.

In flight, the significance of air bags increases many times, because the process of double breathing of the bird occurs. Step by step it looks like this:

1. Wings rise, stretching air bags.
2. The air is injected into the lungs.
3. Part of the gas, without delay, passes into air bags, without losing oxygen. In this organ, gas exchange does not occur.
4. Wings fall, on exhalation through the lungs passes a gas rich in oxygen from air bags.

The phenomenon in which blood is saturated with oxygen on inhalation and exhalation is called double breath. He has great significance in the life of birds. Breathing becomes more frequent as the intensity of the flapping of the wings increases.

Other features of breathing

Double breathing is typical for birds, but some do not have the same number of strokes and respiratory movements. However, certain stages of these processes correspond to time. The presence of air bags helps prevent overheating of birds in flight, because cold air flows around the body from the inside. With their help, the density of the body decreases and the organs rub against each other. The frequency of respiratory movements is different in different species. The volume of air bags is an order of magnitude greater than that of the lungs.