Heart how does it function

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Updated visitor guidelines. You are here Home » How the Heart Works. Top of the page. Topic Overview The heart is at the center of your circulatory system, which is a network of blood vessels that delivers blood to every part of your body. Your heart is a muscle, and its job is to pump blood throughout your circulatory system. How does my heart pump blood?

Your heart is divided into two separate pumping systems, the right side and the left side. The right side of your heart receives oxygen-poor blood from your veins and pumps it to your lungs, where it picks up oxygen and gets rid of carbon dioxide. The left side of your heart receives oxygen-rich blood from your lungs and pumps it through your arteries to the rest of your body.

How does blood flow through the heart? Blood flows through your heart and lungs in four steps: The right atrium receives oxygen-poor blood from the body and pumps it to the right ventricle through the tricuspid valve.

The right ventricle pumps the oxygen-poor blood to the lungs through the pulmonary valve. The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle through the mitral valve. See if you or someone you know is eligible to participate in our clinical trials. To learn more about clinical trials at the NIH Clinical Center or to talk to someone about a study that might fit your needs, call the Office of Patient Recruitment Learn more about participating in a clinical trial.

View all trials from ClinicalTrials. Visit Children and Clinical Studies to hear experts, parents, and children talk about their experiences with clinical research. After reading our How the Heart Works Health Topic, you may be interested in additional information found in the following resources. How the Heart Works. The heart is an organ about the size of your fist that pumps blood through your body. It is made up of multiple layers of tissue.

Your heart is at the center of your circulatory system. This system is a network of blood vessels, such as arteries, veins, and capillaries, that carries blood to and from all areas of your body. Your blood carries the oxygen and nutrients that your organs need to work properly. Blood also carries carbon dioxide to your lungs so you can breathe it out. Inside your heart, valves keep blood flowing in the right direction. A healthy heart supplies your body with the right amount of blood at the rate needed to work well.

A problem with the electrical system—or the nervous or endocrine systems, which control your heart rate and blood pressure—can also make it harder for the heart to pump blood. Explore this Health Topic to learn more about how the heart works, our role in research to improve health, and where to find more information. Anatomy of the interior of the heart.

This image shows the four chambers of the heart and the direction that blood flows through the heart. Oxygen-poor blood, shown in blue-purple, flows into the heart and is pumped out to the lungs. Then oxygen-rich blood, shown in red, is pumped out to the rest of the body, with the help of the heart valves.

Heart chambers. Heart tissue. The heart is made of three layers of tissue. Endocardium, the thin inner lining of the heart chambers that also forms the surface of the valves. Myocardium, the thick middle layer of muscle that allows your heart chambers to contract and relax to pump blood to your body. Pericardium, the sac that surrounds your heart. Made of thin layers of tissue, it holds the heart in place and protects it.

A small amount of fluid between the layers helps reduce friction between the beating heart and surrounding tissues. Read more. Read less. Blood Flow - How the Heart Works. Heart valves. The heart has four valves. The tricuspid valve separates the right atrium and right ventricle. The mitral valve separates the left atrium and left ventricle.

The pulmonary valve separates the right ventricle and the pulmonary artery. The aortic valve separates the left ventricle and aorta. Adding oxygen to blood. The left coronary artery delivers blood to the left side of your heart, including your left atrium and ventricle and the septum between the ventricles. The circumflex artery branches off from the left coronary artery to supply blood to part of the left ventricle.

The left anterior descending artery also branches from the left coronary artery and provides blood to parts of both the right and left ventricles. The right coronary artery provides blood to the right atrium and parts of both ventricles. The marginal arteries branch from the right coronary artery and provide blood to the surface of the right atrium.

The posterior descending artery also branches from the right coronary artery and provides blood to the bottom of both ventricles. After your atria pump blood into the ventricles, the valves between the atria and ventricles close to prevent backflow. At rest, your heart typically beats about 60 to 70 times per minute. When you exercise, your heart beats faster, and your heart rate speeds up to get more oxygen to your muscles. Electrical activity. The signal begins in a group of cells, called pacemaker cells, located in the sinoatrial SA node in the right atrium.

The electrical signal travels through the atria, causing them to pump blood into the ventricles. The electrical signal then moves down to a group of pacemaker cells called the atrioventricular AV node, located between the atria and the ventricles. Here the signal slows down slightly, allowing the ventricles time to finish filling with blood. The AV node fires another signal that travels along the walls of your ventricles, causing them to contract and pump blood out of your heart.

The ventricles relax, and the heartbeat process starts all over again in the SA node. Blood pressure. Systolic pressure is the pressure when the ventricles pump blood out of the heart. The pressure on your arteries is highest during this time. Diastolic pressure is the pressure between beats, when the heart is filling with blood.

The pressure on your arteries is lowest during this time. Autonomic nervous system. The parasympathetic system tells your heart to beat slower during rest. The sympathetic system tells your heart to beat faster. Norepinephrine also signals the muscle in your heart to beat harder. In a healthy person, the heart rate reflects a balance between these two systems. Endocrine system. These hormones include: The renin-angiotensin-aldosterone system, which can also cause the muscle cells in the heart to grow larger so they can pump harder.

This is the most common form of heart disease, known as coronary heart disease sometimes called coronary artery disease or ischaemic heart disease. This can cause angina - a pain or discomfort in your chest, arm, neck, stomach or jaw. If the fatty material breaks off or ruptures, a blood clot will form, which can cause heart attack or stroke, if the artery affected is carrying blood to your brain.

Normally your heart will beat between 60 to times per minute. This regular rhythmic beating is dependent upon electrical signals being conducted throughout your heart. There are some conditions which can damage your heart muscle, making it weak and unable to pump as efficiently as before:.

There are also conditions - like high blood pressure hypertension - which mean your heart has to work harder. This is called heart failure because of the failure of your heart to pump blood around the body and work efficiently. Home Illnesses and conditions Heart and blood vessels About the heart Understanding how your heart functions.

Understanding how your heart functions. Structure of your heart Your heart is made up of three layers of tissue: epicardium myocardium endocardium. How does a healthy heart work? What can go wrong? A healthy heart contraction happens in five stages. In the first stage early diastole , the heart is relaxed.

Then the atrium contracts atrial systole to push blood into the ventricle. Next, the ventricles start contracting without changing volume. Then the ventricles continue contracting while empty. Finally, the ventricles stop contracting and relax. Then the cycle repeats. Valves prevent backflow, keeping the blood flowing in one direction through the heart. By the end of the day, your heart will have beaten around , times around 60 to 80 beats per minute.

This will pump around 1. Heartworm is a disease that affects pets - predominantly dogs - resulting in heart failure and organ damage, according to the U.

The disease is caused by a parasitic worm - called Dirofilaria immitis - which enters the pet's body from an infected mosquito bite.