2010-PSL-200-201--Cardio-02of07

2010-PSL-200-201--Cardio-02of07 - 1 Cardiovascular...

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Unformatted text preview: 1 Cardiovascular Physiology 2/7 Department of Physiology Nohjin Nohjin Kee Kee , Ph.D. , Ph.D. Email: Email: nohjin.kee@utoronto.ca nohjin.kee@utoronto.ca Office Hours TBA Office Hours TBA 2 Pacemaker and AP acemaker and AP 3 Pacemaker and AP Pacemaker cells fire APs in the absence of any external stimulus. A pacemaker cell is able to fire APs spontaneously because it does not have a steady resting potential. The unstable resting E M of the pacemaker cells depolarize slowly and continues to do so until its membrane potential reaches threshold, which triggers an AP. After depolarization, E M returns to -60 mV and then begins another round of slow depolarization until another AP is triggered. acemaker and AP 4 Pacemaker and AP Pacemaker cells fire APs in the absence of any external stimulus. A pacemaker cell is able to fire APs spontaneously because it does not have a steady resting potential. The unstable resting E M of the pacemaker cells depolarize slowly and continues to do so until its membrane potential reaches threshold, which triggers an AP. After depolarization, E M returns to -60 mV and then begins another round of slow depolarization until another AP is triggered. acemaker and AP 5 Pacemaker and AP Pacemaker cells fire APs in the absence of any external stimulus. A pacemaker cell is able to fire APs spontaneously because it does not have a steady resting potential. The unstable resting E M of the pacemaker cells depolarize slowly and continues to do so until its membrane potential reaches threshold, which triggers an AP. After depolarization, E M returns to -60 mV and then begins another round of slow depolarization until another AP is triggered. acemaker and AP 6 Pacemaker cells fire APs in the absence of any external stimulus. A pacemaker cell is able to fire APs spontaneously because it does not have a steady resting potential. The unstable resting E M of the pacemaker cells depolarize slowly and continues to do so until its membrane potential reaches threshold, which triggers an AP. After depolarization, E M returns to -60 mV and then begins another round of slow depolarization until another AP is triggered. Pacemaker and AP acemaker and AP 7 Pacemaker and AP In pacemaker cells electrical signals are caused by changes in plasma membrane ion permeability brought about by the opening and closing of specific types of channels. As a membranes permeability to a particular ion increases relative to that of other ions, the membrane potential moves toward the equilibrium potential of that ion. In cardiac muscle the most important permeability changes involve Na + , Ca ++ & K+ E Na = +60 mV; E Ca = 130 mV; EK = -90 mV acemaker and AP 8 Pacemaker and AP In pacemaker cells electrical signals are caused by changes in plasma membrane ion permeability brought about by the opening and closing of specific types of channels....
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2010-PSL-200-201--Cardio-02of07 - 1 Cardiovascular...

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