What is the structure of the human heart?

Heart Illustration
The heart is located beneath the rib cage slightly to the left of the center of the chest between the lungs and above the diaphragm. A healthy adult heart is approximately the size of a closed fist. The valves and chambers of the heart work together to pump oxygen-rich blood to nourish the body and return oxygen-poor blood to the lungs. In the lungs, carbon dioxide is exchanged for oxygen.

The heart is a muscular organ situated in the chest just behind and slightly toward the left of the breastbone. It roughly measures the size of a closed fist. The heart works all the time, pumping blood through the network of blood vessels called the arteries and veins. The heart and its blood vessels are known as the cardiovascular system.

The heart has four chambers. The upper two chambers are called the atria, whereas the lower two chambers are known as the ventricles. The right atrium and right ventricle are referred to as the right heart, whereas the left atrium and left ventricle are referred to as the left heart. The various chambers of the heart are separated by partitions, each of which is called a septum.

  • The right atrium receives deoxygenated blood from the body and pumps it to the right ventricle.
  • The right ventricle gets blood from the right atrium and pumps it to the lungs to load it with oxygen.
  • The left atrium receives oxygenated blood from the lungs and pumps it to the left ventricle.
  • The left ventricle is the strongest chamber of the heart. It pumps oxygen-rich blood to the rest of the body.

The flow of blood into the heart, within the heart chambers, and from the heart is guarded by the four valves present in the heart. The heart gets its nutrients and oxygen via the coronary arteries that run along the surface of the heart. It is also richly supplied by a web of nerve tissue that facilitates the rhythmic heartbeat. The heart is enclosed within a fluid-filled sac called the pericardium. The pericardium is a protective covering that produces fluid, which lubricates the heart and prevents friction between the heart and the surrounding organs.

What are the four main functions of the heart?

The four main functions of the heart are:

  • Pumping oxygenated blood to the other body parts.
  • Pumping hormones and other vital substances to different parts of the body.
  • Receiving deoxygenated blood and carrying metabolic waste products from the body and pumping it to the lungs for oxygenation.
  • Maintaining blood pressure.

What are the medical conditions related to the heart?

Some of the common diseases of the heart are:

  • Coronary artery disease (CAD): The narrowing of the arteries supplying blood to the heart (coronary arteries). If the arteries develop complete blockage from a suddenly lodged blood clot, the condition is called a heart attack.
  • Stable angina pectoris: Chest pain due to insufficient blood supply to the heart from doing strenuous physical activity. The reason is due to narrowed coronary arteries that are unable to supply sufficient oxygen-rich blood to the heart during exertion. Typically, there is relief from symptoms upon rest.
  • Unstable angina pectoris: Chest pain or discomfort is new in onset, worsening or occurring even at rest. Unstable angina pectoris is an emergency as it may precede a heart attack, serious abnormal heart rhythm or cardiac arrest.
  • Myocardial infarction (MI or heart attack): When a coronary artery is suddenly blocked, some of the heart muscles die as they are starved of oxygen.
  • Arrhythmia (dysrhythmia): Ann abnormal heart rhythm, which may interfere with the ability of the heart to pump blood effectively.
  • Congestive heart failure (CHF): In CHF, the heart is unable to pump blood to body tissues efficiently. The term congestive heart failure refers to the collection of fluid because of a failing heart.
  • Cardiomyopathy: A disease of the heart muscles, which makes the heart abnormally large, thickened and/or stiff. As a result, it weakens the ability of the heart to pump blood.
  • Myocarditis: The inflammation of the heart muscles.
  • Pericarditis: The Inflammation of the covering of the heart (pericardium).
  • Pericardial effusion: In this medical condition, there is a collection of fluid between the covering of the heart (pericardium) and the heart itself.
  • Heart valve diseases: Diseases that affect the valves that direct flow of blood to the heart.
  • Cardiac arrest: A sudden cessation of heart function.


In the U.S., 1 in every 4 deaths is caused by heart disease. See Answer

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Medically Reviewed on 9/14/2021
Medscape Medical Reference