Cardiac Muscle


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•  Structure of cardiac muscle cells allows propagation of stimuli through the heart wall

The heart is composed of cardiac muscle cells which have specialised features that relates to their function:

  • Cardiac muscle cells contract without stimulation by the central nervous system (contraction is myogenic)
  • Cardiac muscle cells are branched, allowing for faster signal propagation and contraction in three dimensions
  • Cardiac muscles cells are not fused together, but are connected by gap junctions at intercalated discs
  • Cardiac muscle cells have more mitochondria, as they are more reliant on aerobic respiration than skeletal muscle

These structural features contribute to the unique functional properties of the cardiac tissue:

  • Cardiac muscle has a longer period of contraction and refraction, which is needed to maintain a viable heart beat
  • The heart tissue does not become fatigued (unlike skeletal muscle), allowing for continuous, life long contractions
  • The interconnected network of cells is separated between atria and ventricles, allowing them to contract separately

Structure of Cardiac Muscle Cells

cardiac muscle