hjärtväv

Hjärtväv, also known as cardiac muscle tissue, is a specialized type of muscle 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, or smooth muscle found in internal organs, cardiac muscle is involuntary, meaning its contractions are not consciously directed.

The cells that make up hjärtväv are called cardiomyocytes. These cells are striated, meaning they have a striped appearance under a microscope, similar to skeletal muscle. However, they are shorter and thicker than skeletal muscle cells and are branched. A key feature of cardiomyocytes is the presence of intercalated discs, which are specialized junctions that connect the cells to each other. These discs allow for rapid and coordinated electrical and mechanical coupling between the cells, ensuring that the heart muscle contracts as a single, unified unit.

The contraction of hjärtväv is initiated by electrical impulses that are generated by specialized pacemaker cells within the heart. These impulses spread through the cardiac muscle via the intercalated discs, causing the cardiomyocytes to depolarize and contract. The rhythm and strength of these contractions are regulated by the autonomic nervous system and various hormones.

Hjärtväv is highly resistant to fatigue due to its abundant mitochondria and rich blood supply, which provide the necessary oxygen and nutrients for continuous energy production. Damage to hjärtväv, such as from a heart attack, can impair the heart's pumping function and lead to serious health consequences.