205textnotes29 - They are anatomically distinct from...

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They are anatomically distinct from contractile cells as they are smaller and contain few contractile fibers and organelles. --------------------------------------------------------------------- C.2. FUNCTION: --------------------------------------------------------------------- C.2.1 Cardiac muscle contraction : Action potentials that originate in cardiac autorhythmic cells (SA node) spread rapidly to the contractile cells through the gap- junctions of the intercalated disks causing subsequent depolarization of the striated cells . Excitation-contraction coupling: Figures 14-11, 14-12 Step 1 : An action potential enters the contractile cell and triggers the opening of voltage-gated Ca 2+ channels. There is entry of Ca 2+ from the extracellular fluid to the cell down its electrochemical gradient. Step 2 : Entry of Ca 2+ induces the release of Ca 2+ from intracellular stores (sarcoplasmic reticulum). This process is called calcium-induced calcium release. Step 3
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This note was uploaded on 12/26/2011 for the course KIN 205 taught by Professor Blaber during the Fall '09 term at Simon Fraser.

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