What is the role of heart in human body?

The heart is the main pump that circulates the blood and fluid within the body. The heart, beats at 72 times per minute, and pumps about 5.5 liters of blood per minute in the average adult. The heart of a young athlete can reach 180 or more beats per minute and can pump over 17 liters of blood per minute.

The human heart has four chambers. The upper chambers receive blood and are called atria (singular atrium; sometimes also called auricles). The lower chambers, or ventricles, pump blood to the lungs and throughout the body. Flaps of tissue called atrioventricular valves prevent blood from flowing back into the atria when the ventricles contract. The atrioventricular or a-v valve, on the right side of the body, leading from the right atrium to the right ventricle, is the tricuspid valve. The one leading from the left atrium to the left ventricle is the bicuspid valve, also called the mitral valve.

The heart consists of two separate pumping systems, the right side for the pulmonary circulation to the lungs, and the left side for systemic circulation to the rest of the body. The heart muscle tissues are supplied with oxygen and nutrients by their own circulatory system. Two arteries, called the coronary arteries, branch from the aorta, the main artery of the heart, just beyond the semilunar valves. These break up into arterioles and capillaries that supply the heart muscles and heart valves. Blood from the capillaries is collected in veins leading into a large vein called the coronary sinus, which directly enters the right atrium.