Health

Video: Heart and Cardiovascular System—How They Work

Your heart is a pump. It is a muscular organ the size of your fist, just to the left of the center of your chest.

The heart and blood vessels work together to form the cardiovascular system, which circulates blood and oxygen around the body.

Your mind is divided into four rooms. These include the two on the right, called the right atrium and right ventricle, and the two on the left, called the left atrium and left ventricle. This department prevents oxygen-rich blood from mixing with oxygen-deficient blood.

The heart has four valves that open in one direction only when needed to keep blood moving in the right direction. These valves include the tricuspid valve, mitral valve, lung valve, and aortic valve. Each valve has a flap called a leaflet or cusp that opens and closes once per heartbeat.

At the beginning of the pump cycle, the low-oxygen blood, shown here in blue, circulates in the body and then returns to the heart.

Low-oxygen blood fills the right atrium and then flows into the right ventricle, where it is pumped through the pulmonary arteries to the lungs. The lungs refresh the blood with a supply of new oxygen coming from the air you inhale.

The oxygen-rich blood shown in red returns from the lungs into the left atrium. Oxygen-rich blood then flows from the left atrium to the left ventricle. Blood is then pumped through the major arteries that supply blood to the body, called the aorta, which supplies oxygen to tissues throughout the body.

Your heart is also nourished by blood. Oxygen-rich blood comes from the coronary arteries that extend to the surface of the heart.

The beating heart contracts and relaxes. Contraction is called systole and relaxation is called diastole.

During systole, the ventricles contract, pumping blood into the blood vessels that go to the lungs and body.

The ventricles then relax during diastole and are filled with blood coming from the upper, left and right atriums. Then the cycle starts again.

This cycle is driven by the heart’s electrical wiring, called the conduction system. The electrical impulse begins high in the sinoatrial node of the right atrium and travels through special pathways to the ventricles, signaling the heart.

The conduction system keeps the heart beating in a regulated, normal rhythm and maintains blood circulation. This continuously exchanges oxygen-rich blood for oxygen-deficient blood, which is needed to stay alive.

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