Mechanics of the Breathing Process

Respiration is one of the most important vital functions of humans and other mammals, which ensures gas exchange between the cell and the environment. The breathing process in humans consists of three phases: external respiration, transfer of gases by blood and internal respiration. In this article we will look at the mechanics of external respiration, which is the mechanical process of filling the lungs with air (inhalation) and releasing this air out (exhalation).

The breathing cycle, consisting of inhalation and exhalation, is repeated in humans 15-18 times per minute. When you inhale, the intercostal muscles contract, pulling the anterior ends of the ribs up and forward due to the “hinge” of the ribs with the spine. At the same time, the diaphragm, which forms the bottom of the chest cavity, contracts and becomes less convex in its upper part, which also increases the volume of the chest cavity. The space of the chest cavity is closed, and this increase in volume leads to a decrease in pressure in the lungs. When the pressure drops below atmospheric pressure, outside air rushes through the trachea and bronchi into the alveolar sacs and alveoli.

When you exhale, air is pushed out of the lungs due to the elasticity of the lungs themselves and the heaviness of the chest walls. During inhalation, the lungs expand as they fill with air. After relaxation of the intercostal muscles, the ribs are able to return to their original position, and the simultaneous relaxation of the diaphragm leads to the fact that, under the pressure of the organs located in the abdominal cavity, it again takes on its previous dome-shaped shape. As a result, the volume of the chest cavity decreases, which allows the stretched elastic tissue of the lungs to compress and push out the air that entered the lungs during inspiration.

The muscles of the abdominal wall also contract, causing the abdominal organs to press upward on the diaphragm and thereby further accelerate the elastic compression of the lungs. When breathing, the walls of the chest cavity never put pressure on the lungs and do not squeeze air out of them; reducing the volume of the chest cavity only allows the lungs to shrink due to their own elasticity.

Coughing and sneezing are forms of forced exhalation, in which, due to vigorous muscle contraction, the bronchial tree and alveoli of the lungs are quickly cleared of mucus, dust and other harmful particles.

So, the mechanics of external respiration is to fill the lungs with air when you inhale and push that air out when you exhale. This process is controlled by the respiratory center located in the brain, which regulates the frequency and depth of breathing depending on the body's needs for oxygen and carbon dioxide.

Although breathing is an automatic process, we can control it consciously, for example, when performing various physical exercises or during meditation. In addition, proper breathing can help manage stress and improve overall health.