szívizomösszehúzódásainak

szívizomösszehúzódás is the Hungarian term for myocardial contraction or heart muscle contraction. It refers to the physiological process by which the heart muscle, the myocardium, shortens and thickens, propelling blood throughout the body. This rhythmic contraction and relaxation is fundamental to the circulatory system and is regulated by a complex electrical and mechanical system.

The process begins with an electrical impulse generated by the sinoatrial (SA) node, often called the heart's natural pacemaker. This impulse travels through the heart's electrical conduction system, causing the cardiac muscle cells to depolarize. Depolarization triggers the release of calcium ions within the muscle cells, which initiates the interaction of actin and myosin filaments, the contractile proteins. This interaction leads to the shortening of the sarcomeres, the basic contractile units of the muscle, resulting in the overall contraction of the heart chamber.

During systole, the phase of contraction, the atria contract to fill the ventricles, and then the ventricles contract forcefully to pump blood into the pulmonary artery (to the lungs) and the aorta (to the rest of the body). Following contraction, the heart muscle enters diastole, the phase of relaxation, during which the chambers refill with blood in preparation for the next beat. The coordinated and efficient sequence of szívizomösszehúzódás ensures adequate blood flow to meet the body's oxygen and nutrient demands. Disruptions in this process can lead to various cardiovascular conditions.