hjartavöðvi

Hjartavöðvi, also known as the myocardium, is the specialized cardiac muscle tissue that forms the middle layer of the heart wall. 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 organs like the digestive tract, cardiac muscle is involuntary and exhibits unique properties.

The cells that make up the hjartavöðvi are called cardiomyocytes. These cells are interconnected by specialized junctions called intercalated discs, which contain gap junctions. These junctions allow electrical impulses to pass rapidly from one cell to another, enabling the heart to beat as a coordinated unit. The rhythmic contraction and relaxation of the hjartavöðvi are controlled by the heart's electrical conduction system.

The thickness of the hjartavöðvi varies in different chambers of the heart. The left ventricle, which pumps blood to the entire body, has the thickest layer of muscle, reflecting the greater workload it performs. The right ventricle, which pumps blood only to the lungs, has a thinner wall. The atria, which receive blood returning to the heart, have the thinnest walls as they only need to pump blood into the ventricles.

Damage to the hjartavöðvi, such as from a heart attack, can impair the heart's ability to pump effectively, leading to serious health consequences. Understanding the structure and function of the hjartavöðvi is crucial for comprehending cardiovascular health and disease.