The heart functions as a pump that sends blood around the body
. It is a muscle about the size of your fist, located in the middle of your chest
. The heart beats around 60 to 100 times per minute, with each beat sending blood throughout the body
. The heart has two pumps: the right heart, which pumps blood through the lungs, and the left heart, which pumps blood through the peripheral organs
. Each of these hearts is a pulsatile two-chamber pump composed of an atrium and a ventricle
. How the heart works:
- Oxygen-poor blood enters the right atrium
. The right atrium collects and pumps the blood to the lungs through the pulmonary arteries
- The lungs refresh the blood with oxygen, and the oxygen-rich blood enters the left side of the heart
- The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle
- The left ventricle pumps the oxygen-rich blood through the aorta to supply tissues with oxygen
- The heart's electrical system coordinates the contraction of the heart chambers
. The sinus node generates an electrical stimulus, which causes the atria to contract
. The electrical impulse travels to the atrioventricular node, then down the bundle of His into the ventricles, stimulating the right and left ventricles
- Contraction is called systole, which forces blood into the vessels going to the lungs and body
. Relaxation is called diastole, during which the ventricles fill with blood
