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Day 4: Chapter 18 (Heart )
Terms in this set (10)
What are the two types of myocytes ?
contractile cells (99%) and autorhymic cells (ARC) (1%)
What is the role of contractile cells ??
eject blood from the heart to the circulation , stimulate to initiate an AP , and specialize to CONTRACT
What is the role of ARC cells ?
NON-CONTRACTILE cells , specialized to initiation action potentials , flow throughout the heart to spread to stimulate contractile cells , have a unstable RMP, and contain a intense conduction system
Role of gap junctions ?
link adjacent cardiac muscle cells together by membrane proteins to allow the movement of ions so electric activity can spread by way of contractile cells and ARC cells to produce a action potential
Which type of cell exhibits a pacemaker potential ?
ARC cells in order to spontaneously depolarize to threshold and generate an AP
What does gap junctions carry ?
carry electrical currents continuing ions , which the movement of ions has a charge that spread to cells to create a action potential
What is the value of an unstable PMP (pace maker potential)
What does a unstable PMP cause ?
a decrease in potassium permeability and cause activating gates to open for calcium to bring more positive charges in and depolarization to threshold occurs (-60>>>-40) (T-type)
What does depolarization to threshold cause?
Activation of the 2nd type of calcium gated channel (L-type) to initiate the rising phase (occurs longer )
What happens at the peak of the PMP?
decrease permeability to calcium by closing channel and increase in permeability of potassium by opening ion channels fro potassium (efflux) and Membrane potential returns back to -60 and the cycle will begin again .
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