The Vascular System
The vascular system is part of the human cardiovascular system and ensures that blood reaches all areas where it is required. With each heartbeat (contraction and ejection phase, systole), the heart pumps blood from the left ventricle into the arterial vascular system. Between beats (relaxation and filling phase, diastole), blood flows back into the heart from the venous vascular system. In this way, the heart ensures that blood circulation in the vascular system remains active.
With each beat (systole), the heart pumps blood that has been enriched with oxygen in the lungs from the left ventricle into the large artery (aorta). Branches (arteries) branch off from the aorta, through which the blood reaches the various regions of the body and is distributed everywhere via increasingly smaller branches of the arteries. In the smallest branches, the capillaries, the exchange of nutrients, metabolic products and oxygen between the blood and tissue takes place. This happens in the skin and in all other organs such as the kidneys, brain, liver, etc., which can thus perform their functions, such as metabolising nutrients, excreting metabolic products, producing and secreting hormones, and so on.
The "used" blood collects in small veins, which merge into larger and larger veins. Finally, the inferior and superior vena cavae flow into the right atrium of the heart. The pumping action of the heart causes the venous blood to enter the right atrium of the heart during diastole, from where it flows through the right ventricle into the pulmonary circulation. Here, the blood is re-oxygenated, passes through the left atrium of the heart into the left ventricle, and the cycle begins again.
