The Heart: How It Works

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.

The heart has several large arteries and veins connected to it that branch out and become smaller as they travel throughout your body. Your arteries and veins deliver blood throughout your body in a process called circulation. Arteries are blood vessels that carry oxygenated blood away from your heart. The aorta is the largest blood vessel in your body. The aorta carries all the blood that is pumped out of your heart and through its many branches, distributes blood to all of the organs and throughout the body. Two main coronary arteries branch off the aorta to supply the heart with oxygen, blood, and nutrients to keep it healthy. Veins are vessels that carry blood from your body and lungs back to your heart. Your two largest veins are the superior and inferior vena cava.

Small blood vessels called capillaries connect your arteries and veins. Capillaries deliver oxygen and nutrients at a cellular level. They also remove waste products, such as carbon dioxide. Carbon dioxide is produced after your cells have used oxygen. Additionally, about 20% of your blood flows through your kidneys. Your kidneys filter waste products from your blood.

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.

Your doctor will check your pulse. Your pulse is the beat that is felt each time your heart contracts. You pulse can most easily be felt my lightly pressing on the skin that covers your large arteries, such as at your wrist or the side of your neck. Your pulse increases when you are excited, active, or exercising because your body needs more oxygen to function. Your pulse is slower when you are relaxed and resting.

It is important to keep your heart healthy. You need a heart to survive. Keep your heart muscle healthy and strong with regular exercise. Eat healthy well-balanced meals. Avoid foods that contain unhealthy fats, such as saturated fats and trans fats. Do not smoke; smoking can damage the heart and blood vessels.


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This information is intended for educational and informational purposes only. It should not be used in place of an individual consultation or examination or replace the advice of your health care professional and should not be relied upon to determine diagnosis or course of treatment.
The iHealthSpot patient education library was written collaboratively by the iHealthSpot editorial team which includes Senior Medical Authors Dr. Mary Car-Blanchard, OTD/OTR/L and Valerie K. Clark, and the following editorial advisors: Steve Meadows, MD, Ernie F. Soto, DDS, Ronald J. Glatzer, MD, Jonathan Rosenberg, MD, Christopher M. Nolte, MD, David Applebaum, MD, Jonathan M. Tarrash, MD, and Paula Soto, RN/BSN. This content complies with the HONcode standard for trustworthy health information. The library commenced development on September 1, 2005 with the latest update/addition on April 13th, 2016. For information on iHealthSpot’s other services including medical website design, visit