The heart is the core of the cardiovascular system. Your cardiovascular system consists of your heart and the blood vessels that carry blood throughout your body. Your heart is located to the left of the middle of your chest. Your heart is a large muscle is about the size of your fist. It works as a pump. The blood carries nutrients and oxygen that your body cells need for energy. It also carries waste products away.
Your heart is divided into four sections called chambers. The chambers are separated by the septum, a thick muscle wall. The two top chambers are called atria, and they receive blood coming into the heart. The two bottom chambers are called ventricles, and they send blood out from the heart.
Your heart contains two pumping systems, one on its left side and one on its right side. The left-sided pumping system consists of the left atrium and the left ventricle. Your left atrium receives blood that contains oxygen, which comes from your lungs. Whenever you inhale, your lungs move oxygen into your blood. The oxygenated blood moves from the left atrium to the left ventricle. The left ventricle sends the oxygenated blood out from your heart to circulate throughout your body.
The heart’s right-sided pumping system consists of the right atrium and the right ventricle. Your right atrium receives deoxygenated blood, blood that has circulated throughout your body and does not have high levels of oxygen in it anymore. The deoxygenated blood moves from the right atrium to the right ventricle. The right ventricle sends the blood to the lungs where it receives oxygen when you breathe.
As the blood travels through the heart chambers, four valves keep the blood from back flowing. The mitral valve and the tricuspid valve regulate blood flow from the atria to the ventricles. The aortic valve and the pulmonary valve control blood as it leaves the ventricles.
Your doctor will listen to your heartbeat with a stethoscope. A healthy heart makes a lub-dub sound each time it beats. The first sound in your heartbeat occurs when the mitral valve and the tricuspid valve close. The second sound in your heartbeat occurs when the aortic valve and the pulmonary valve close after the blood leaves your heart.