Cardiac Myocyte Action Potential Flashcards
(32 cards)
What is the resting membrane potential in ventricular myocardium?
~ -90mV
What ion is the membrane more permeable to during the resting potential?
K+
What balances K+ efflux to maintain cell potential?
K+ influx
What occurs during Phase 0 of the cardiac myocyte action potential?
Rapid depolarization
What happens at threshold potential in Phase 0?
Rapid Na+ influx occurs through fast sodium channels
What is the threshold potential approximately in mV?
~ -70 mV
What causes the short downward deflection in Phase 1?
Outward flow of K+ and Cl-
What characterizes Phase 2 of the cardiac action potential?
Plateau phase
What ions move during Phase 2?
- Inward Ca++ movement through L-type calcium channels
- Outward K+ movement through delayed-rectifier channels
What occurs during Phase 3 of the cardiac myocyte action potential?
Rapid repolarization
What happens to L-type Ca++ channels during Phase 3?
They close
What remains open during Phase 3, allowing continued K+ movement?
Delayed-rectifier K+ channels
At what membrane potential do delayed-rectifier K+ channels close?
~ -90mV
Fill in the blank: The potassium concentration is higher _______.
intracellularly
True or False: The membrane potential rises past 0 mV during Phase 0.
True
What determines the depolarization upstroke in Phase 1?
Rate of sodium influx
What is the resting membrane potential in ventricular myocardium?
~ -90mV
What ion is the membrane more permeable to during the resting potential?
K+
What balances K+ efflux to maintain cell potential?
K+ influx
What occurs during Phase 0 of the cardiac myocyte action potential?
Rapid depolarization
What happens at threshold potential in Phase 0?
Rapid Na+ influx occurs through fast sodium channels
What is the threshold potential approximately in mV?
~ -70 mV
What causes the short downward deflection in Phase 1?
Outward flow of K+ and Cl-
What characterizes Phase 2 of the cardiac action potential?
Plateau phase
