Without food, a person can live for several weeks, without water - only a few days, and without air after 4 minutes, damage to brain cells and further death occurs. 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. What path does air travel before it reaches the lungs? This long journey begins when air passes through the mouth or nose into the throat. As you know, in the pharynx the respiratory and digestive tracts intersect. So that food or liquid does not get into the airways during swallowing, there is a small lid known as the epiglottis that closes the entrance to them.
Through the larynx past the vocal cords, the air rushes into the trachea or respiratory throat (its length is 12 cm). Throughout its entire length, the trachea is strengthened by approximately twenty horseshoe-shaped cartilages. At the end, 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 branches. Each new branch is getting thinner. The air goes into small branches - small vessels with a diameter of up to 1 mm, called bronchioles.
Further, the air fills 300,000 even smaller channels - alveoli sacs. They are clustered in the lungs and look like tiny 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 ideally the lungs are located in our body - on both sides of the heart. The right lung includes three lobes, and the left - two. Such anatomy helps surgeons: the respiratory system will work quite successfully even after some diseased lung lobe has been removed.
The lung tissue resembles the structure of a sponge. The lower part of the lungs are adjacent to the diaphragm. This strong muscular septum separates the chest cavity from the abdominal cavity. The diaphragm is called the most important respiratory muscle, it is involved in the work of constant expansion and contraction of the lungs.
Each lung is covered by a thin shell - pleura. The inside of the chest is also covered with a similar membrane. Between the layers is a lubricating fluid. Due to this structure, both the lungs and the chest glide freely during breathing.
The final vestibule of inhaled air
When air reaches the alveoli, it comes in contact with a network of the thinnest blood vessels - pulmonary capillaries. Red blood cells (red blood cells) can pass through the capillaries only one at a time, their diameters are so narrow. Through the thinnest walls (0.5 microns) carbon dioxide passes into the alveolus. Oxygen leaves the alveoli, being absorbed by red blood cells.
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 change places. This amazing gas exchange process is called diffusion. Blood, enriched with oxygen, enters the pulmonary veins and reaches the left half of the heart and from there is pumped throughout the body.
Imagine, it takes only a minute for all the blood to pass all this complicated breathing relay!
Breathing is an automatic system.
Healthy lungs automatically absorb air while breathing approximately 14 times per minute. Although this automation can be deliberately suspended by holding your breath, it can only be done for a couple of minutes. For example, this is necessary during diving or in a polluted room, but after this time, the lungs, in accordance with the ingenious program laid down in them, will inevitably revert to automatic operation. Where is the control center of this “automation” located? In the brain stem, special receptors monitor the content of carbon dioxide in 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 forcedly activated by the body.
What a miracle this is - the respiratory system, presented to us by the Creator!