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Where a person has a diaphragm

Conditionally, the diaphragm can be drawn along thethe lower edge of the ribs. The tip of the right dome of the diaphragm is usually at the level of the fourth intercostal space, the top of the left dome is at the level of the fifth. When breathing in, the diaphragm domes flatten and fall 2-3 cm. In the diaphragm, three parts are distinguished in the diaphragm: the sternum, the rib and the lumbar. From the posterior surface of the xiphoid process begins the sternal part. The widest rib part starts on the inner surface of the bone and cartilage parts of the six lower ribs. The lumbar part is divided into the right and left legs. Each of them comes from the anterolateral surface of 1-3 lumbar vertebrae and tendon lumbar-rib ligament.

There are three holes in the diaphragm: aortic, esophageal and hollow vein.

Why you need a diaphragm

The diaphragm plays the role of the main respiratorymuscle. When contracted, it flattenes, which increases the volume of the chest and inspiration. When relaxed, the diaphragm assumes a convex spherical shape, which reduces the chest and provides exhalation.

Involuntary trembling contractions of the diaphragm lead to hiccups.

The diaphragm also performs a support (static)function, supporting the normal arrangement of the organs of the thoracic and abdominal cavities, contributes to the outflow of venous blood from the liver and the inferior vena cava to the heart and the movement of food through the esophagus.

Mechanisms of inspiration and expiration

When you inhale, the diaphragm descends and moves awayorgans of the abdominal cavity. The thorax is raised by the intercostal muscles up, forward and sideways. Following the increase in the volume of the chest cavity, the gases contained in the lungs press them to the parietal pleura. The pressure inside the pulmonary alveoli falls, and in them comes the external air. The respiration begins with the relaxation of the intercostal muscles. The thoracic wall falls under the action of gravity, the stretched wall of the stomach begins to press on the organs of the abdominal cavity, those on the diaphragm, and the diaphragm rises. With a decrease in the volume of the chest cavity, the lungs are squeezed, which increases the air pressure in the pulmonary alveoli (it becomes higher than the atmospheric one) and contributes to the escape of a part of the air to the outside.

Regulation of respiration

The concentration of oxygen and carbon dioxide in the bloodmust be maintained at a constant level. The respiratory center, consisting of the centers of inspiration and exhalation, which regulate the work of the respiratory muscles, is located in the medulla oblongata. Inhalation is reflexively caused by the collapse of the pulmonary alveoli, exhalation by their expansion. It is also possible to consciously influence the rhythm of breathing.