Birds expend an enormous amount of energy during flight. Their mode of movement has had a great impact on all organ systems. Birds cannot afford large and heavy organs, so the emphasis was on their efficiency. As a result, the respiratory system of birds, which has been constantly improving in the course of evolution, is today one of the most complex among all vertebrates.
Instructions
Step 1
Air enters the bird's body through two nostrils located above the beak. After that, through the pharynx, it enters the long trachea. Passing into the chest cavity, the trachea is divided into two bronchi. In the place of branching of the trachea in birds, there is an expansion - the so-called lower larynx. This is where the vocal cords are located. The lungs in birds are located in the body cavity differently from in humans. They are firmly attached to the ribs and spinal column, have little elasticity and cannot stretch when filled with oxygen.
Step 2
Air passes through the lungs in transit. Only about 25% of the supplied oxygen remains in this organ. The main part rushes further - into air bags. Birds have five pairs of air sacs, which are outgrowths of the branches of the bronchi. Air bags are capable of stretching when air enters them. This will be the inhalation of the bird.
Step 3
When you exhale, the air from the air sacs rushes back into the lungs and then goes out. Thus, although the work of the lungs of birds can be called insufficiently intense in comparison with the lungs of a person, thanks to double breathing, the bird receives a sufficient amount of oxygen for it.
Step 4
At rest, birds breathe due to the expansion and contraction of the chest. During the flight, the thorax of birds remains practically motionless, and the breathing process is carried out already due to other mechanisms. When the wings are raised, the air sacs of the bird stretch, and air is involuntarily sucked into the lungs, and then into the bags. When the bird lowers its wings, air is pushed out of the air sacs. The more intensively the bird flaps its wings, the more often it breathes.
