Large (bodily) circle of blood circulation.
The large (bodily) circulation of blood serves to deliver nutrients and oxygen to all organs and tissues of the body and remove metabolic products and carbon dioxide from them. It begins in the left ventricle of the heart, from which the aorta extends, which carries arterial blood. Arterial blood contains nutrients and oxygen necessary for the vital functions of the body, and has a bright scarlet color. The aorta forks into arteries that go to all organs and tissues of the body and pass into the thickness of the arterioles and further into the capillaries. The capillaries, in turn, are collected in the venules and further into the veins. Through the wall of capillaries, metabolism and gas exchange occur between the blood and body tissues. The arterial blood flowing in the capillaries gives off nutrients and oxygen and in return receives metabolic products and carbon dioxide (tissue respiration). As a result, the blood entering the venous bed is poor in oxygen and rich in carbon dioxide and therefore has a dark color – venous blood; in case of bleeding, it is possible to determine by blood color whether the artery or vein is damaged. The veins merge into two large trunks – the upper and lower hollow veins, which flow into the right atrium. This part of the heart ends with a large (bodily) circle of blood circulation. In addition to the large circle, there is a third (heart) circulation that serves the heart itself. It begins with the coronary arteries of the heart emerging from the aorta and ends with the veins of the heart. The latter merge into the coronary sinus, which flows into the right atrium, and the small veins open into the atrial cavity directly.
Regional blood circulation. The total circulatory system with its large and small circles of blood circulation functions differently in different areas and organs of the body, depending on the nature of their function and functional needs at the moment. Therefore, besides the general circulation, there are local, or regional (from the Latin. Regio – region), blood circulation. It is carried out by trunk and organ vessels, which have their own special structure in each separate organ. To understand the regional circulation of blood matters the correct understanding of the microcirculation of blood.