Can you imagine a house in which a complex piping system is installed, filled with very valuable liquid, which uninterruptedly transports water, food, oxygen and removes waste? In addition, the pipes themselves are able to restore themselves and build up, adapting to changes in the house. Such an engineering structure would be admired by everyone.
But our circulatory system is capable of more. It regulates body temperature, moves a huge number of different hormones that carry important information to all cells, and organizes protection against pathogens. This network is completely flexible and soft, so it is able to absorb all impacts and bend along with the body. Let's take a closer look at this masterpiece .
The structure of the human circulatory system
In the center of the circulatory system is a hollow organ - the heart, which, like a pump, continuously pumps blood in a vicious circle consisting of blood vessels.
The whole system is divided into two components:
• Small circle of blood circulation. A vascular system that connects the heart and lungs together. This circle begins in the right ventricle, its end lies in the left atrium. Applies only to the lungs.
• A large circle of blood circulation. It originates in the aorta and ends in the right atrium.
The great circle of blood circulation with its vessels permeates the whole body.
The heart with the help of a longitudinal septum is divided into two parts. Each of these parts is also divided into two halves with the help of a horizontal septum, forming a ventricle and atrium.
Blood first enters the most important vessel of our body - the aorta. Further, the aorta is divided into smaller vessels, and the blood passes into the arteries of the pulmonary circulation. Gradually, the arteries branch and pass into the arterioles and capillaries. The diameter of the capillaries is very small - about 10 microns. This means that red blood cells transporting oxygen to cells pass through the capillaries one at a time. The walls of the capillary vessels are very thin - they consist of only one layer of cells, but this does not prevent the supply of tissues with nutrients located in the liquid part of the blood (plasma). At the same time, carbon dioxide and metabolic products that require removal from the body are transferred from the tissues to the capillaries.
The capillaries have a small loop-shaped muscle with which they can regulate the flow of blood passing through them to meet the needs of nearby tissues. When the blood leaves the capillaries, it enters the microscopic veins - venules. The venules further merge into the veins, through which the blood continues to pass a large circle of blood circulation, returning to the heart. In the veins, blood pressure is lower than in the arteries, but the lumen of the venous vessels is greater.
How is reverse movement ensured?
Thanks to simply ingenious adaptation:
• Cup-shaped valves that prevent blood from flowing out of the heart under the influence of gravity.
• The work of skeletal muscles that squeeze closely spaced veins, pushing blood through one-way valves in the direction of the heart.
• Internal pressure in the chest and abdomen, which changes during breathing and helps the veins pump blood into the right atrium.
When venous valves for some reason (pregnancy, genetic inheritance, obesity or long standing) do not work well, blood builds up under the valves and the veins swell. This condition is called varicose veins.
A large circle of blood circulation provides oxygen and brain cells. Therefore, the blood circulation of the brain is carried out according to the same laws as for all other organs. If venous outflow from the vessels of the brain is difficult, then dizziness and headaches occur.
Surprisingly, the efficiency of the human circulatory system is so high that even during rest in one minute about 5 liters of blood passes through the heart, and a marathoner has about 35 liters every minute.
As you can see, our Creator is really a great designer, whose handiwork - a large circle of blood circulation - is admirable!