Sydänliaksesta

Sydänliaksesta, also known as cardiac muscle or myocardium, is a specialized type of muscle tissue found exclusively in the heart. It is responsible for the heart's ability to contract and pump blood throughout the body. Unlike skeletal muscle, which is under voluntary control, cardiac muscle is involuntary, meaning its contractions are not consciously controlled.

The structure of cardiac muscle cells, or cardiomyocytes, is unique. They are striated, similar to skeletal muscle, with a regular arrangement of contractile proteins. However, cardiac muscle cells are branched and interconnected by specialized junctions called intercalated discs. These discs contain gap junctions, which allow electrical impulses to spread rapidly from one cell to another, enabling coordinated contractions of the entire heart muscle.

The rhythmic and powerful contractions of the myocardium are essential for maintaining circulation. The heart's electrical system initiates these contractions, with signals originating in the sinoatrial (SA) node, the heart's natural pacemaker. From the SA node, the impulse travels through the atria, causing them to contract, then to the atrioventricular (AV) node, and finally to the ventricles, which then contract to pump blood out to the lungs and the rest of the body.

The metabolic demands of cardiac muscle are very high, requiring a constant supply of oxygen and nutrients. It primarily relies on aerobic metabolism, with a rich network of capillaries supplying blood to the muscle tissue. Conditions that compromise blood flow to the heart, such as coronary artery disease, can lead to damage and dysfunction of the sydänliaksesta, potentially resulting in serious health issues like heart attacks.