The heart is a powerful muscular organ that pumps blood through the body. It delivers oxygen and nutrients to tissues and removes waste products. With every beat, the heart maintains circulation of the blood. The heart is enclosed in a sac called the pericardium for protection. Its four chambers—two atria and two ventricles—work in perfect sync. Valves ensure that blood flows in one direction only. The right side manages deoxygenated blood, and the left handles oxygen-rich blood. Blood is pushed to the lungs via the pulmonary artery and returns via the pulmonary vein. Finally, oxygenated blood is pumped through the aorta to the entire body. This cycle repeats over 100,000 times each day, keeping us alive.
The heart’s function relies on its electrical conduction system. It starts with the SA node generating impulses that spread through the atria. These impulses cause the atria to contract and push blood into the ventricles. Then, the signal travels to the AV node and down the bundle branches. This triggers contraction of the ventricles to pump blood out. The right ventricle sends blood to the lungs, while the left sends it to the body. The cardiac cycle includes systole (contraction) and diastole (relaxation). The coronary arteries supply blood to the heart tissue itself. Valves open and close with each beat to maintain direction. This rhythmic process is automatic, coordinated, and vital to life.