The Cardiac muscle reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Cardiac muscle

Cardiac muscle is a type of striated muscle found within the heart. Its function is to "pump" blood through the circulatory system; contraction.

Cardiac muscle generally operates "involuntarily" and rhythmically, without receiving nerve stimulation. Cardiac muscle is myogenic, which means that it is self-exciting. This is in contrast with skeletal muscle, which requires either conscious or reflex nervous stimuli. The rate of cardiac contractions is generally determined by pacemaker cells. However, each individual cell will contract without input. When individual cells are in close proximity they can share their signal and will contract in unison, their frequency being determined by the cell with the shortest interval. Individual cardiac cells are joined by intercalated discs.

See also: skeletal muscle, smooth muscle

Muscular system

Cardiac muscle - Skeletal muscle - Smooth muscle List of muscles of the human body

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