Sydänlihakset

Sydänlihakset, also known as cardiac muscle tissue, are a specialized type of muscle found exclusively in the heart of vertebrates. These muscles are responsible for the heart's ability to pump blood throughout the body. Unlike skeletal muscles, which are under voluntary control, or smooth muscles, which are found in internal organs and are involuntary, cardiac muscles are involuntary and exhibit automaticity, meaning they can contract rhythmically without external stimulation.

The structure of cardiac muscle cells, called cardiomyocytes, is unique. They are striated, similar to skeletal muscle, due to the arrangement of contractile proteins actin and myosin. However, cardiomyocytes are branched and interconnected by specialized junctions called intercalated discs. These discs contain gap junctions that allow electrical impulses to pass rapidly from one cell to another, enabling the heart to contract as a coordinated unit.

The primary function of sydänlihakset is to generate the force needed for cardiac output. This continuous contraction and relaxation cycle is essential for delivering oxygen and nutrients to all tissues and removing waste products. The energy for these contractions is primarily derived from aerobic metabolism, with cardiac muscle having a high density of mitochondria. Damage to sydänlihakset, such as that occurring during a myocardial infarction (heart attack), can impair the heart's pumping ability and have serious health consequences.