Amazing device - the human respiratory system

Without food, a person can live for several weeks, without water - only a few days, and without air after 4 minutes, there is damage to the brain cells and later death. The respiratory system of our body is a truly wonderful device.

How does the human respiratory system work?

The respiratory tract consists of interconnected passages and ducts. Which way passes the air before it reaches the lungs? This long path begins when air through the mouth or nose gets into the pharynx. As is known, in the throat the respiratory and digestive pathways cross. To food or liquid during swallowing did not get into the respiratory tract, there is a small lid, known as the epiglottis, closing the entrance to them.

Through the larynx past the vocal cords air rushes into the trachea or the windpipe (its length is 12 cm). Over its entire length, the trachea is strengthened by approximately twenty cartilage cartilage. At the end of the trachea is divided into two tubes of 2.5 cm - the main bronchi. They enter the right and left lungs, where they branch into many bronchi.

The branching of the bronchi resembles the structure of a tree with a trunk, branches and thin branches and twigs. Each new branch is becoming thinner. The air is directed into small twigs - small vessels up to 1 mm in diameter, called bronchioles.

Further, the air fills 300 000 even smaller channels - bags of alveoli. They are clusters in the lungs and look like the smallest bubbles. Here the tree-like respiratory system ends and the air reaches its final destination.

The structure of the lungs - the main organ of the respiratory system

It is worth mentioning how perfectly located in our body are the lungs - on both sides of the heart. The right lung includes three lobes, and the left lung - two. Surgeons are assisted by such anatomy: the respiratory system will work quite successfully even after the removal of some sore portion of the lung.

Pulmonary tissue resembles the structure of a sponge. The lower part of the lungs are adjacent to the diaphragm. This strong muscular septum separating the thoracic cavity from the abdominal cavity. The diaphragm is called the most important muscle of respiration, it participates in the work of constant expansion and narrowing of the lungs.

Each lung is covered by a thin membrane - pleura. The inner side of the chest is also covered with a similar shell. Between the layers is a lubricating fluid. Thanks to this structure, both the lungs and the thorax freely slide during respiration.

The final threshold of inhaled air

When the air reaches the alveoli, it comes into contact with a network of the thinnest blood vessels - the pulmonary capillaries. Erythrocytes of blood (red blood cells) can pass through the capillaries only one at a time, their diameters are so narrow. Through the thinnest walls (0.5 μm) carbon dioxide passes into the alveolus. Oxygen also leaves the alveoli, being absorbed by erythrocytes.

Only three quarters of one second the red blood cell remains in the capillaries. In this short time, carbon dioxide and oxygen have time to swap places. This amazing process of gas exchange is called diffusion. Blood, enriched with oxygen, enters the pulmonary veins and reaches the left half of the heart and from there it is pumped all over the body.

Imagine, all the blood will take just a minute, so that all this complicated respiratory relay has been completely passed!

Breathing is an automatic system

Healthy lungs automatically about 14 times per minute absorb the air during breathing. Although this automation can be deliberately suspended, holding your breath, but this can only be done for a couple of minutes. For example, it is necessary during diving or in a gassed room, but after this time, the lungs according to the ingenious program laid in them will inevitably revert to the automatic mode of operation. Where is the control center of this "automation"? In the brain stem, special receptors monitor the carbon dioxide content of the blood. When the level exceeds the permissible mark, the brain will send signals through the network of nerves and the respiratory muscles will be forcibly activated by the body.

What a miracle is the respiratory system, given to us by the Creator!