What is the heart?
The heart is a fist-sized organ that pumps blood throughout your body. It's the primary organ of your circulatory system.
Your heart contains four main sections (chambers) made of muscle and powered by electrical impulses. Your brain and nervous system direct your heart’s function.
What does a heart diagram look like?
The inside and outside of your heart contain components that direct blood flow:
Inside of the Heart
Outside of the Heart
What is the heart’s function?
Your heart’s main function is to move blood throughout your body. Your heart also:
- Controls the rhythm and speed of your heart rate.
- Maintains your blood pressure.
How does your heart work with other organs?
Your heart works with other body systems to control your heart rate and other body functions. The primary systems are:
- Nervous system: Your nervous system helps control your heart rate. It sends signals that tell your heart to beat slower during rest and faster during stress.
- Endocrine system: Your endocrine system sends out hormones. These hormones tell your blood vessels to constrict or relax, which affects your blood pressure. Hormones from your thyroid gland can also tell your heart to beat faster or slower.
Where is your heart located?
Your heart is located in the front of your chest. It sits slightly behind and to the left of your sternum (breastbone). Your ribcage protects your heart.
What side is your heart on?
Your heart is slightly on the left side of your body. It sits between your right and left lungs. The left lung is slightly smaller to make room for the heart in your left chest.
How big is your heart?
Everyone’s heart is a slightly different size. Generally, adult hearts are about the same size as two clenched fists, and children’s hearts are about the same size as one clenched fist.
How much does your heart weigh?
On average, an adult’s heart weighs about 10 ounces. Your heart may weigh a little more or a little less, depending on your body size and sex.
What are the parts of the heart’s anatomy?
The parts of your heart are like the parts of a house. Your heart has:
- Chambers (rooms).
- Valves (doors).
- Blood vessels (plumbing).
- Electrical conduction system (electricity).
Your heart walls are the muscles that contract (squeeze) and relax to send blood throughout your body. A layer of muscular tissue called the septum divides your heart walls into the left and right sides.
Your heart walls have three layers:
- Endocardium: Inner layer.
- Myocardium: Muscular middle layer.
- Epicardium: Protective outer layer.
The epicardium is one layer of your pericardium. The pericardium is a protective sac that covers your entire heart. It produces fluid to lubricate your heart and keep it from rubbing against other organs.
Your heart is divided into four chambers. You have two chambers on the top (atrium, plural atria) and two on the bottom (ventricles), one on each side of the heart.
- Right atrium: Two large veins deliver oxygen-poor blood to your right atrium. The superior vena cava carries blood from your upper body. The inferior vena cava brings blood from the lower body. Then the right atrium pumps the blood to your right ventricle.
- Right ventricle: The lower right chamber pumps the oxygen-poor blood to your lungs through the pulmonary artery. The lungs reload blood with oxygen.
- Left atrium: After the lungs fill blood with oxygen, the pulmonary veins carry the blood to the left atrium. This upper chamber pumps the blood to your left ventricle.
- Left ventricle: The left ventricle is slightly larger than the right. It pumps oxygen-rich blood to the rest of your body.
Your heart valves are like doors between your heart chambers. They open and close to allow blood to flow through.
The atrioventricular (AV) valves open between your upper and lower heart chambers. They include:
- Tricuspid valve: Door between your right atrium and right ventricle.
- Mitral valve: Door between your left atrium and left ventricle.
Semilunar (SL) valves open when blood flows out of your ventricles. They include:
- Aortic valve: Opens when blood flows out of your left ventricle to your aorta (artery that carries oxygen-rich blood to your body).
- Pulmonary valve: Opens when blood flows from your right ventricle to your pulmonary arteries (the only arteries that carry oxygen-poor blood to your lungs).
Your heart pumps blood through three types of blood vessels:
- Arteries carry oxygen-rich blood from your heart to your body’s tissues. The exception is your pulmonary arteries, which go to your lungs.
- Veins carry oxygen-poor blood back to your heart.
- Capillaries are small blood vessels where your body exchanges oxygen-rich and oxygen-poor blood.
Your heart receives nutrients through a network of coronary arteries. These arteries run along your heart’s surface. They serve the heart itself.
- Left coronary artery: Divides into two branches (the circumflex artery and the left anterior descending artery).
- Circumflex artery: Supplies blood to the left atrium and the side and back of the left ventricle.
- Left anterior descending artery (LAD): Supplies blood to the front and bottom of the left ventricle and the front of the septum.
- Right coronary artery (RCA): Supplies blood to the right atrium, right ventricle, bottom portion of the left ventricle and back of the septum.
Electrical conduction system
Your heart’s conduction system is like the electrical wiring of a house. It controls the rhythm and pace of your heartbeat. It includes:
- Sinoatrial (SA) node: Sends the signals that make your heart beat.
- Atrioventricular (AV) node: Carries electrical signals from your heart’s upper chambers to its lower ones.
Your heart also has a network of electrical bundles and fibers. This network includes:
- Left bundle branch: Sends electric impulses to your left ventricle.
- Right bundle branch: Sends electric impulses to your right ventricle.
- Bundle of His: Sends impulses from your AV node to the Purkinje fibers.
- Purkinje fibers: Make your heart ventricles contract and pump out blood.
Conditions and Disorders
What conditions and disorders affect the human heart?
Heart conditions are among the most common types of disorders affecting people. In the United States, heart disease is the leading cause of death for people of all genders and most ethnic and racial groups.
Common conditions that affect your heart include:
- Atrial fibrillation (Afib): Irregular electrical impulses in your atrium.
- Arrhythmia: A heartbeat that is too fast, too slow or beats with an irregular rhythm.
- Cardiomyopathy: Unusual thickening, enlargement or stiffening of your heart muscle.
- Congestive heart failure: When your heart is too stiff or too weak to properly pump blood throughout your body.
- Coronary artery disease: Plaque buildup that leads to narrow coronary arteries.
- Heart attack (myocardial infarction): A sudden coronary artery blockage that cuts off oxygen to part of your heart muscle.
- Pericarditis: Inflammation in your heart’s lining (pericardium).
How can I keep my heart healthy?
If you have a condition that affects your heart, follow your healthcare provider’s treatment plan. It’s important to take medications as prescribed.
You can also make lifestyle changes to keep your heart healthy. You may:
- Achieve and maintain a healthy weight for your sex and age.
- Drink alcohol in moderation.
- Eat a heart-healthy diet with plenty of fruits, vegetables and whole grains.
- Exercise moderately for at least 150 minutes per week.
- Limit your sodium intake.
- Manage your stress with healthy strategies like meditation or journaling.
- Quit smoking and/or using tobacco products and avoid secondhand smoke.
Frequently Asked Questions
What should I ask my doctor about my heart?
You may want to ask your healthcare provider:
- How does my family history affect my heart health?
- What can I do to lower my blood pressure?
- How do my cholesterol levels affect my heart?
- What are the symptoms of a heart attack?
- What foods should I eat to prevent heart disease?
A note from Cleveland Clinic
Your heart is the primary organ of your circulatory system. It pumps blood throughout your body, controls your heart rate and maintains blood pressure. Your heart is a bit like a house. It has walls, rooms, doors, plumbing and an electrical system. All the parts of your heart work together to keep blood flowing and send nutrients to your other organs. Conditions that affect your heart are some of the most common types of conditions. Ask your healthcare provider how you can improve your heart health.
The heart is a fist-sized organ that pumps blood throughout your body. It's the primary organ of your circulatory system. Your heart contains four main sections (chambers) made of muscle and powered by electrical impulses. Your brain and nervous system direct your heart's function.What are the 3 main functions of the heart? ›
As the central part of the circulatory system, the heart is responsible for pumping blood, supplying oxygen and nutrients, and removing metabolic waste such as carbon dioxide from all the tissues in the body.What are the 4 main parts of the heart? ›
The heart is made up of four chambers. The upper two chambers are called atria (singular: atrium) and the lower two are known as ventricles (singular: ventricle). Muscular walls, called septa or septum, divide the heart into two sides.What do the 4 valves of the heart do? ›
Two of the valves, the mitral and the tricuspid valves, move blood from the upper chambers of the heart (the atria) to the lower chambers of the heart (the ventricles). The other two valves, the aortic and pulmonary valves, move blood to the lungs and the rest of the body through the ventricles.Which heart function is most important? ›
It's the muscle at the centre of your circulation system, pumping blood around your body as your heart beats. This blood sends oxygen and nutrients to all parts of your body, and carries away unwanted carbon dioxide and waste products.What are the 12 steps of blood flow through the heart? ›
Blood flows through the heart in the following order: 1) body –> 2) inferior/superior vena cava –> 3) right atrium –> 4) tricuspid valve –> 5) right ventricle –> 6) pulmonary arteries –> 7) lu ngs –> 8) pulmonary veins –> 9) left atrium –> 10) mitral or bicuspid valve –> 11) left ventricle –> 12) aortic valve –> 13) ...What are the basics of the heart? ›
The heart is a pump, usually beating about 60 to 100 times per minute. With each heartbeat, the heart sends blood throughout our bodies, carrying oxygen to every cell. After delivering the oxygen, the blood returns to the heart. The heart then sends the blood to the lungs to pick up more oxygen.How does the heart function step by step? ›
The right ventricle pumps the low-oxygen blood to the lungs to pick up a fresh supply of oxygen. The left atrium receives to high-oxygen blood from the lungs and pumps it to the left ventricle. The left ventricle pumps the high-oxygen blood to the rest of the body.How many arteries are in the heart? ›
The 2 main coronary arteries are the left main and right coronary arteries.How does blood flow through the heart step by step? ›
Blood comes into the right atrium from the body, moves into the right ventricle and is pushed into the pulmonary arteries in the lungs. After picking up oxygen, the blood travels back to the heart through the pulmonary veins into the left atrium, to the left ventricle and out to the body's tissues through the aorta.
The heart will appear white if it has been drained of blood.What artery is the largest? ›
The aorta is the largest blood vessel in your body. It's more than 1 foot long and an inch in diameter at its widest point.What are the 3 layers of the heart? ›
The wall of the heart separates into the following layers: epicardium, myocardium, and endocardium. These three layers of the heart are embryologically equivalent to the three layers of blood vessels: tunica adventitia, tunica media, and tunica intima, respectively.What nerve supplies the heart? ›
The network of nerves supplying the heart is called the cardiac plexus. It receives contributions from the right and left vagus nerves, as well as contributions from the sympathetic trunk. These are responsible for influencing heart rate, cardiac output, and contraction forces of the heart.What are the two main parts of the heart? ›
A typical heart has two upper and two lower chambers. The upper chambers, the right and left atria, receive incoming blood. The lower chambers, the more muscular right and left ventricles, pump blood out of the heart.What is the bottom of the heart called? ›
ventricles (VEN-trih-kuhls): The two chambers at the bottom of the heart are called the ventricles. The heart has a left ventricle and a right ventricle.Which artery is the largest and why? ›
The largest artery is the aorta, the main high-pressure pipeline connected to the heart's left ventricle. The aorta branches into a network of smaller arteries that extend throughout the body.Which valve is important in heart? ›
Aortic valve: This valve has three leaflets. They open to let blood flow from your heart's left ventricle to the aorta. The aorta is the largest blood vessel in your body. It brings oxygenated blood from your heart to the rest of your body.What is the right heart valve called? ›
The tricuspid valve sits between the heart's two right chambers. The tricuspid valve consists of three thin flaps of tissue (called cusps, or leaflets). These valve flaps open to let blood flow from the upper right chamber (right atrium) to the lower right chamber (right ventricle).What is the most powerful part of the heart? ›
The left ventricle is the strongest because it has to pump blood out to the entire body. When your heart functions normally, all four chambers work together in a continuous and coordinated effort to keep oxygen-rich blood circulating throughout your body.
However, when it really comes down to it, the most important steps that anyone can take to help prevent heart disease fall into one of two main categories: Remaining physically active and maintain a healthy weight.Is the heart a muscle or an organ? ›
The heart is a hollow muscular organ about the size of a closed fist. It's in the centre of your chest, behind the breastbone. Each heartbeat sends blood that's rich in oxygen and nutrients to all parts of your body.How do you memorize heart anatomy? ›
Of note, there are other mnemonics, such as “Try Pulling My Aorta” where T stands for tricuspid, P stands for pulmonary, M stands for Mitral, and A stands for aortic, that can assist in remembering the the anatomical positions of the heart valves and the order in which blood flows through the heart.What carries blood to the heart? ›
A network of arteries and veins also carry blood throughout the body: Arteries transport blood from the heart to the body tissues. Veins carry blood back to the heart.How many valves does the heart have? ›
A normal heart and heart valve problems
The four heart valves, which keep blood flowing in the right direction, are the mitral, tricuspid, pulmonary and aortic valves. Each valve has flaps (leaflets) that open and close once per heartbeat.
The heart is made up of four chambers: two upper chambers known as the left atrium and right atrium and two lower chambers called the left and right ventricles. It is also made up of four valves: the tricuspid, pulmonary, mitral and aortic valves.What controls the heart function? ›
Heart rate is controlled by the two branches of the autonomic (involuntary) nervous system. The sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). The sympathetic nervous system (SNS) releases the hormones (catecholamines - epinephrine and norepinephrine) to accelerate the heart rate.What is pumping of heart called? ›
The heart's blood pumping cycle, which is called the cardiac cycle, begins when oxygen-free blood returns to the heart through the right atrium, after distributing oxygen and nutrients to other parts of the body. The blood then moves into the right ventricle, which facilitates a transfer of blood into the lungs.Which artery is the most common to have blockage? ›
Although blockages can occur in other arteries leading to the heart, the LAD artery is where most blockages occur.Which coronary artery is most commonly blocked? ›
The LAD artery is the most commonly occluded of the coronary arteries.
This condition is called atherosclerosis. The buildup is called plaque. Plaque can cause the arteries to narrow, blocking blood flow. The plaque can also burst, leading to a blood clot.How does blood leave the heart? ›
Arteries and veins go into and out of the heart. Arteries carry blood away from the heart and veins carry blood to the heart. The flow of blood through the vessels and chambers of the heart is controlled by valves.What makes the heartbeat sound we hear? ›
Heart sounds are created from blood flowing through the heart chambers as the cardiac valves open and close during the cardiac cycle. Vibrations of these structures from the blood flow create audible sounds — the more turbulent the blood flow, the more vibrations that get created.What color is the sick heart? ›
It's time we start seeing red. Red — as in the color of heart disease awareness, just as pink is the color we all take notice of in regard to breast cancer.How powerful is a human heart? ›
The hardest working muscle is the heart. It pumps out 2 ounces (71 grams) of blood at every heartbeat. Daily the heart pumps at least 2,500 gallons (9,450 liters) of blood. The heart has the ability to beat over 3 billion times in a person's life.Do women's heart beat faster? ›
The human heart beats approximately 70 to 85 times per minute in an average adult, with a notable difference between the genders. The average adult male heart rate is between 70 and 72 beats per minute, while the average for adult women is between 78 and 82 beats.Which artery has the most oxygen? ›
The pulmonary vein carries oxygen around the body back to the heart. It, therefore, has the greatest oxygen content. The primary pulmonary artery, also known as the pulmonary trunk, is a blood vessel that leaves the heart.What artery is the smallest? ›
Capillaries. Capillaries, the smallest and most numerous of the blood vessels, form the connection between the vessels that carry blood away from the heart (arteries) and the vessels that return blood to the heart (veins).What is the body's largest vein? ›
The vena cava has two parts: the superior vena cava and the inferior vena cava. The superior vena cava carries blood from the head, neck, arms, and chest. The inferior vena cava carries blood from the legs, feet, and organs in the abdomen and pelvis. The vena cava is the largest vein in the body.What is the heart muscle name? ›
The muscle layer of the heart is termed the myocardium and is made up of cardiomyocytes. The myocardium is found in the walls of all four chambers of the heart, though it is thicker in the ventricles and thinner in the atria.
The human body contains three different kinds of muscle tissue: skeletal, smooth, and cardiac. Only cardiac muscle tissue, comprising cells called myocytes, is present in the heart.What is pericardium vs myocardium? ›
The myocardium is the middle and thickest layer of the heart wall. (Myo- means "muscle.") Most of the heart wall is the myocardium. It also houses the cardiac electroconductive system (SA node, AV node, HIS fibers, and Purkinje fibers). PERICARDIUM: makes up the outer layers of the heart wall, enclosing the heart.How many main functions does the heart have? ›
The two main functions of the heart are to pump deoxygenated blood to the lungs in order to receive oxygen, and then to pump oxygenated blood out to all body parts. The circulatory system works to pump blood all throughout the body, carrying with it important molecules such as oxygen and nutrients.What is 10 heart function? ›
A normal heart pumps blood out of its left ventricle at about 50 to 70 percent — a measurement called an ejection fraction, according to the American Heart Association. “Don was at 10 percent, which is basically a nonfunctional heart,” Dow said. “When a heart is pumping at only 10 percent, a person can die very easily.Is the heart a Muscle or an organ? ›
The heart is a hollow muscular organ about the size of a closed fist. It's in the centre of your chest, behind the breastbone. Each heartbeat sends blood that's rich in oxygen and nutrients to all parts of your body.What are the main organs of the heart? ›
The heart is made up of four chambers: two upper chambers known as the left atrium and right atrium and two lower chambers called the left and right ventricles. It is also made up of four valves: the tricuspid, pulmonary, mitral and aortic valves.In which order does blood flow through the heart? ›
Blood comes into the right atrium from the body, moves into the right ventricle and is pushed into the pulmonary arteries in the lungs. After picking up oxygen, the blood travels back to the heart through the pulmonary veins into the left atrium, to the left ventricle and out to the body's tissues through the aorta.What number is heart failure? ›
40 to 55% – Below normal heart function. Can indicate previous heart damage from heart attack or cardiomyopathy. Higher than 75% – Can indicate a heart condition like hypertrophic cardiomyopathy, a common cause of sudden cardiac arrest. Less than 40% – May confirm the diagnosis of heart failure.What number is a strong heart? ›
A score of 120/80 is optimal, and 140/90 is normal for most people. Higher readings mean that arteries aren't responding right to the force of blood pushing against artery walls (blood pressure), directly raising the risk of heart attack or stroke.What are the 4 types of heart failure? ›
- Left-sided heart failure. Left-sided heart failure is the most common type of heart failure. ...
- Right-sided heart failure. The right heart ventricle is responsible for pumping blood to your lungs to collect oxygen. ...
- Diastolic heart failure. ...
- Systolic heart failure.