The heart is a remarkable organ. It beats 100,000 times, and pumps about 2,000 gallons of blood, each day. At rest, the heart muscles are still working twice as hard as your leg muscles during a full-out sprint. Your heart is responsible for pumping blood throughout your entire body, delivering oxygen and nutrients to your body's cells and eliminating waste from tissues and organs.
The heart is about the size of a fist. It is divided into four chambers-two on the left side and two on the right. The two upper chambers are called the atria. They collect blood that comes into the heart. The two lower chambers are the ventricles, which pump blood out of the heart to the lungs and other parts of the body.
Oxygen-poor blood enters the heart from the right side through two large veins, the inferior and superior vena cava, and collects in the right atrium. From the right atrium, the blood travels through the tricuspid valve into the right ventricle. Valves are important because they act like doors in the heart, allowing blood to pass from one chamber to the other while preventing it from flowing backward. The right ventricle contracts to send oxygen-poor blood out of the heart through the pulmonary valve and into the pulmonary arteries, where it is taken to the lungs to be replenished with oxygen.
From the lungs, oxygenated blood travels back into the left side of the heart through the pulmonary veins. From the left atrium, blood flows through the mitral valve into the left ventricle. The left ventricle is the largest and strongest part of the heart and is often described as the main pumping chamber. It pumps blood out of the heart, through the aortic valve, into the aorta. From the aorta, oxygen-rich blood is carried through arteries and capillaries throughout the body, delivering the oxygen and nutrients it needs to survive.
Once you have a basic idea of how the heart operates, you can understand why it is so important to keep it healthy. Heart disease, in any form, occurs when any one of these functions is impaired. When the heart has to work harder, your whole body suffers. Taking good care of your heart helps your entire body, at every level.