The heart

The heart is a vital organ in the bodies of most animals, including humans, that functions primarily as a pump to circulate blood throughout the body's circulatory system. The heart is located in the thoracic cavity, medially between the lungs in the chest. It is a key component of the cardiovascular system, which also includes blood vessels such as arteries, veins, and capillaries.

The human heart is roughly the size of a large fist and is composed of four chambers: the two upper chambers are called the atria (singular: atrium), and the two lower chambers are known as the ventricles. The heart is divided into the right and left side by a wall of muscle called the septum. The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs for oxygenation. This process is part of the pulmonary circulation. The left side of the heart receives oxygenated blood from the lungs and pumps it throughout the body, a process known as the systemic circulation.

The heart's pumping action is regulated by an electrical conduction system that 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.

Several diseases and conditions can affect the heart, including coronary artery disease, heart failure, arrhythmias, and valvular heart disease. Prevention and treatment of heart disease involve lifestyle modifications such as diet, exercise, and smoking cessation, as well as medications and surgical interventions in more severe cases.