Definition
Body circulation describes the system in which blood is pumped from the heart into the body and back again. On the other hand, the pulmonary circulation, also called the small circulation, in which the blood, which is low in oxygen, is transported from the heart to the lungs, where it is enriched with oxygen and flows back to the heart. The body’s circulation includes the heart and all the vessels through which the blood flows through the body.
The body’s circulation begins in the heart, in the left ventricle. From this ventricle, the blood is expelled into the aorta. The aorta runs from the heart in a slight downward arc completely through the entire trunk.
Numerous other arteries branch off from the aorta. From these, in turn, further arteries branch off, which divide further into arterioles and finally into capillaries. Capillaries are the smallest vessels of the body’s circulation.
This is where the exchange of oxygen and nutrients in return for metabolic end products such as carbon dioxide takes place between the blood and the corresponding supplied organ. The aorta is divided at the end in the pelvic area into the two major pelvic arteries (Arteriae iliacae communes). From these two pelvic arteries, further arteries, arterioles and capillaries are branched off, which are responsible for supplying the lower extremities, i.e. the legs and feet.
At the point where the aorta exits the left ventricle, the aorta describes an arc, the so-called arcus aortae. At this arch, important arteries branch off, among others, which will be further divided into arteries, arterioles and capillaries for the supply of the upper extremities (arms and legs) and the head. In order for the blood to flow back to the heart after supplying organs and other structures, the capillaries open into venules.
These venules then connect further to form larger veins. These veins ultimately all open into the great vena cava. This great vena cava can be divided into two areas, the superior vena cava and the inferior vena cava.
The inferior great vena cava is formed by the confluence of the two great veins from the lumbar region (Venae iliacae communes) and takes in numerous other veins from the pelvic and abdominal regions, thus absorbing all the blood from the area below the diaphragm. The superior vena cava is responsible for the area above the diaphragm. It therefore contains the blood that flows from the arms and head back to the heart and results from the confluence of the two larger vessels of the right and left brachiocephalic veins. Both large vena cava flow into the right atrium of the heart from below and above respectively.
