Anatomy of the human heart

Anatomy of the Human Heart

Diagram 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 closed fist. The heart is composed of four chambers: two atria and two ventricles.

Structure

The heart is divided into four chambers:

• Right Atrium: Receives deoxygenated blood from the body through the superior vena cava and inferior vena cava.
• 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.

The heart is enclosed in a double-walled sac called the pericardium, which provides protection and lubrication.

Function

The primary function of the heart is to maintain a continuous flow of blood throughout the body. This is achieved through a series of coordinated contractions known as the cardiac cycle. The cycle consists of two main phases:

• Systole: The phase of contraction where blood is ejected from the ventricles.
• Diastole: The phase of relaxation where the heart chambers fill with blood.

The heart's rhythm is regulated by the sinoatrial node, often referred to as the natural pacemaker.

Blood Supply

The heart muscle itself requires a constant supply of oxygen-rich blood, which is delivered by the coronary arteries. These arteries branch off from the aorta and encircle the heart.

Electrical Conduction System

The heart's electrical conduction system controls the heartbeat. It includes the sinoatrial node, atrioventricular node, bundle of His, and Purkinje fibers. This system ensures that the heart beats in a coordinated and efficient manner.

Related Pages

• Cardiovascular system
• Blood pressure
• Heart disease
• Electrocardiogram