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Overview

Illustration of the human heart

The human heart is a muscular organ responsible for pumping blood through the circulatory system. It is located in the thoracic cavity between the lungs and is roughly the size of a fist. The heart is composed of four chambers: two upper chambers called atria and two lower chambers called ventricles.

Structure

The heart is divided into the right and left sides, each with an atrium and a ventricle. The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs for oxygenation, while the left side receives oxygenated blood from the lungs and pumps it to the rest of the body.

Chambers

• Right Atrium: Receives deoxygenated blood from the superior vena cava, inferior vena cava, and coronary sinus.
• Right Ventricle: Pumps deoxygenated blood to the lungs via the pulmonary artery.
• Left Atrium: Receives oxygenated blood from the lungs through the pulmonary veins.
• Left Ventricle: Pumps oxygenated blood to the body through the aorta.

Valves

The heart contains four main heart valves that ensure unidirectional blood flow:

• Tricuspid Valve: Located between the right atrium and right ventricle.
• Pulmonary Valve: Located between the right ventricle and pulmonary artery.
• Mitral Valve: Located between the left atrium and left ventricle.
• Aortic Valve: Located between the left ventricle and aorta.

Function

The primary function of the heart is to maintain blood circulation throughout the body. It achieves this through a coordinated sequence of contractions and relaxations known as the cardiac cycle. The heart's electrical conduction system, including the sinoatrial node, atrioventricular node, and Purkinje fibers, regulates the heartbeat.

Blood Supply

Diagram showing the coronary arteries

The heart muscle, or myocardium, receives its blood supply from the coronary arteries. These arteries branch off from the aorta and encircle the heart, providing oxygen and nutrients to the heart tissue.

Related pages

• Cardiovascular system
• Electrocardiography
• Heart disease
• Cardiac muscle