Kjarnavöðva

Kjarnavöðva is the Icelandic term for the heart muscle, also known as cardiac muscle or myocardium. This specialized type of muscle tissue is found only in the heart. Its primary function is to pump blood throughout the body. Unlike skeletal muscles, which are under voluntary control, kjarnavöðva is involuntary. This means its contractions are not consciously directed but are instead regulated by the body's autonomic nervous system and the heart's own internal pacemaker system.

The cells that make up kjarnavöðva are called cardiomyocytes. These cells are unique in several ways. They are striated, meaning they have a striped appearance under a microscope, similar to skeletal muscle. However, they are also branched and interconnected by specialized junctions called intercalated discs. These discs allow electrical impulses to pass quickly from one cell to another, enabling the heart to contract in a coordinated and rhythmic manner.

Kjarnavöðva is incredibly resilient and capable of continuous work throughout an individual's life without fatigue. This is due to its high density of mitochondria, which are responsible for generating energy. The rich blood supply to the heart muscle ensures it receives a constant supply of oxygen and nutrients necessary for its sustained function. Conditions affecting kjarnavöðva can lead to various heart diseases, highlighting its critical role in maintaining life.