Cardiac muscle

Cardiac muscle is the involuntary, striated tissue of the heart. Its interconnected cells contract rhythmically to generate the force that pumps blood.

Cardiomyocyte: A specialized heart muscle cell that contracts and connects electrically with neighboring cells. Cardiomyocytes are the contractile cells whose coordinated activity produces cardiac muscle contraction.
Sarcomere: The repeating contractile unit of striated muscle, built from organized actin and myosin filaments. Sarcomeres give cardiac muscle its striated appearance and produce contraction.
Skeletal muscle: Striated muscle tissue that is usually controlled voluntarily and moves the skeleton. Unlike cardiac muscle, skeletal muscle fibers are long, multinucleated cells under voluntary control.
Myocardial infarction: Heart muscle injury or death caused by prolonged inadequate blood flow, usually after a coronary artery blockage. Ischemia deprives cardiac muscle of oxygen and can irreversibly damage its cells.
Intercalated disc: A specialized junction between cardiac muscle cells containing mechanical and electrical connections. Intercalated discs bind neighboring cells and help electrical impulses spread through the tissue.
Actin: A protein that forms thin filaments and participates in cellular structure and movement. Thin actin filaments slide past myosin during cardiac muscle contraction.
Smooth muscle: Non-striated, involuntary muscle tissue found in the walls of many hollow organs and vessels. Its lack of sarcomeric striations distinguishes it from cardiac muscle.
Cardiomyopathy: A disease of the heart muscle that impairs the heart’s structure or pumping function. These disorders directly alter cardiac muscle performance and can lead to heart failure.
Gap junction: A channel between adjacent cells that permits ions and small molecules to pass directly between them. Gap junctions let depolarization pass between cardiomyocytes, synchronizing contraction.
Myosin: A motor protein that uses ATP to move along actin filaments and generate force. Myosin cross-bridges pull on actin to shorten cardiac sarcomeres.

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