The heart | Body Circulation

The heart

The heart is a hollow muscular organ and represents the center of the body’s circulation. It ensures that the blood is expelled into the aorta and is thus also pumped through the entire body. The heart consists of the left and right atrium and the left and right ventricle.

From the left ventricle, the muscularly stronger chamber, the blood is expelled into the aorta. When the blood returns from the body’s circulation to the heart, the blood first flows into the right atrium. From here the blood flows into the right ventricle.

From the right ventricle, the blood flows through the small circulation, the pulmonary circulation, to the lungs to be enriched with oxygen. When the blood returns from the lungs to the heart, it first flows to the left atrium and from there to the left ventricle. Here the body’s circulation begins again.

Vessels

The vessels make up the main part of the body’s circulation. A distinction is made between vessels that flow away from the heart and thus bring blood to the organs, and vessels that flow back to the heart and thus bring the blood back to the heart and thus also to the lungs for oxygenation. The vessels that flow away from the heart (they are usually shown in red in illustrations for oxygen-rich blood) are the aorta, the arteries and the arterioles.

Usually the capillaries are also included. The vessels that lead back to the heart are the venules and the veins. In illustrations, these are usually drawn in blue, for blood low in oxygen.

Physiology

There are various components that support a functioning body circulation. First of all, this is the power of the heart. Because the heart is able to contract, i.e. the muscle tissue of the heart contracts, sufficient blood volume is given into the aorta with every heartbeat and the blood is pumped further in the vessels.

This process can also be felt as a pulse at various points, such as the wrist at the radial and ulnar arteries.Next, the elasticity of the vessels must be ensured. This elasticity means that the vessels can passively expand and contract again with the blood volume. This is particularly important for the air vessel function of the aorta.

The air vessel function describes the phenomenon that blood is pumped into the aorta after a heartbeat. This causes the aorta to expand to accommodate the expelled blood. As the heart relaxes, the aorta also relaxes and the blood reservoir is pushed further away from the heart.

This also compensates for the large difference in pressure between systole (tension and ejection time of the heart) and diastole (relaxation and filling phase of the heart) between the heart and aorta. Equally important is the elasticity in all other vessels of the human body. These too must be able to expand or contract. For example, they can adapt to external conditions. One of these conditions is that vessels narrow when they lack volume so that the smaller blood volume does not sink into the periphery, for example into the vessels of the legs.