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The heart functions as a continuous double muscular pump that beats approximately 100,000 times a day to keep blood constantly moving throughout the body. Physiologically, this organ is divided into four chambers: two upper chambers called atria, which receive blood, and two lower chambers called ventricles, which pump it out.
The cycle begins when deoxygenated blood from the entire body returns to the heart through the venae cavae and enters the right atrium. This chamber contracts and pushes the blood through the tricuspid valve into the right ventricle. When the right ventricle contracts, it sends the blood to the lungs through the pulmonary artery. There, the blood releases carbon dioxide and is replenished with fresh oxygen.
Once oxygenated, the blood returns to the heart through the pulmonary veins and enters the left atrium. From there, it passes through the mitral valve into the left ventricle, which is the thickest and most powerful chamber of the heart. It pumps the blood with great force into the aorta to distribute it throughout the entire body.
All of this mechanical movement is perfectly coordinated by an intrinsic electrical system that generates its own impulses. The electrical signal begins in the sinoatrial node, the natural pacemaker located in the right atrium, which sends a signal causing both atria to contract simultaneously. This electrical current then travels to the atrioventricular node and rapidly spreads through the ventricles via the bundle of His and Purkinje fibers, causing the ventricles to contract.
This cyclic process consists of two main phases: diastole, the relaxation phase when the chambers fill with blood, and systole, the contraction and emptying phase. Together, these phases ensure a continuous and vital flow of blood throughout the body.
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2026-08-18 13:25:00