About Your Heart

Function of the Heart

The human heart is a hollow muscular organ the size of a fist. It consists of four different size chambers: the right and left upper chambers (atria) and the right and left lower chambers (venticles). The heart pumps blood through the body to supply it with oxygen and nutrients.

A healthy adult’s heart weighs about 300 to 400 grams. Each minute the heart pumps 5 to 7 liters of blood through the body. The human heart beats about 100,000 times a day, pumping about 7000 liters of blood—proof that the heart is a very hard-working muscle indeed. Physical exertion means that working muscles need substantially more blood at short notice, while the blood requirements of other organs such as the gut remain low. This need-adapted blood supply is regulated by the nervous system.

The heart valves open and close to let the blood flow only forward but not backward. The sinus node is the heart’s natural pacemaker. It generates a regular impulse which is conducted to the ventricles. The muscle fibers of the left ventricle (main pumping chamber) contract to pump blood from the heart into the circulatory system. The pulse is the result of the heart contracting and relaxing.

The Cardiovascular System

The cardiovascular system consists of the heart and all the blood vessels in which blood circulates. The function of the cardiovascular system is to adequately supply the tissues and organs of the body with blood. The blood in turn supplies each individual cell with nutrients and oxygen, and removes harmful waste products.

The cardiovascular system

• supplies all organs with blood replenished with oxygen in the lungs (arterial system);

• returns blood low in oxygen and high in carbon dioxide to the lungs (venous system).