The circulatory organs in the human body allow the blood to perform all the necessary functions. The essence of blood circulation is the movement of blood through the vessels to provide the necessary substances to all human organs. The entire circulatory system is composed of blood vessels and the heart. Due to the contraction of the heart muscle, the blood spreads through the vessels. There are two types of vessels: arteries (carry blood from the heart muscle to organs and tissues) and veins through which blood flows to the heart. Between themselves, all the vessels are connected by the smallest blood capillaries.
In humans, the following circles of blood circulation are distinguished : small, large. The trunk or large circle originates in the left ventricle of the heart. Then the blood flows into the main artery in the human body - the aorta. Blood flows from the aorta along the spine, thanks to smaller arteries. When they reach the organs, the arteries are divided into arterioles, smaller vessels, which in turn are divided into capillaries. So organs and tissues are saturated with oxygen and nutrients necessary for the normal functioning of the body. Similarly, originating from the capillaries, venous blood enters the two large veins of the body, the lower and upper. Then it is delivered to the right atrium. This whole cycle is a big circle of blood circulation.
Pulmonary, or in another small circle, blood circulation makes a shorter path. A large artery departs from the right ventricle of the heart, which is divided into two pulmonary arteries. So blood enriched with oxygen is delivered to the lungs. Large arteries are divided into arterioles, and those, in turn, are divided into capillaries. It is they that make it possible to saturate the lungs with oxygen and purify them from carbon dioxide. So there is an exchange of gases in the lungs. Then venous blood flows through the veins into the left atrium.
Small and large circles of blood circulation are similar functions of all organs. Arteries deliver blood, saturated with nutrients and oxygen, to organs and tissues. Veins, in turn, return venous blood to the heart. The only difference is the distance: large and small. Circulatory circulation function to saturate the body's cells with oxygen.
But blood circulation circles do not carry all the blood that is in the body. A certain amount of blood is retained in the blood depots. They are located in the spleen, liver, lungs and in the accumulation of blood vessels under the skin. Such depots are necessary for the emergency saturation of organs and tissues with oxygen.
The distribution of blood between the individual organs of the body is not uniform. Circulatory circulation supplies blood depending on the activity of an organ or tissue. This occurs as the vessels expand and contract. Blood flows to an actively working organ in larger quantities due to a decrease in blood flow in other, less active organs.
Circulatory circulation works due to the system of blood vessels, and, of course, the heart muscle. Arteries are responsible for the delivery to the organs and tissues of blood enriched with oxygen and nutrient components. Thanks to them, high pressure is maintained, which ensures the rapid movement of blood through the capillaries and saturation of tissues and organs.
Blood passing through the circles of blood circulation contains the products of the vital activity of the human body and carbon dioxide. Such blood is carried by vessels called veins.
Capillaries also play an important role in the entire circulatory system. This is an extensive network of small vessels through which blood saturated with nutrients and oxygen enters directly into the muscles and tissues of organs.
The whole circulatory system is of great importance in the life of the body. The heart, blood vessels and blood circulation circles are its main components.