QuestionSBA
QuestionChoice
There is rapid Na+ inflow through open fast Na+ channels leading to a rise in membrane potential from -90mV to above 0mV. This causes the rapid depolarisation in phase 0 of a cardiac myocyte action potential.
10006496
a
Inflow of Na+
QuestionChoice
The inflow of Ca2+ through L-type Ca2+ channels is electrically balanced by the outflow of K+ through delayed K+ channels. This causes the plateau in phase 2 of a cardiac myocyte action potential.
10006498
c
Slow inflow of Ca2+
QuestionChoice
Na+ and Ca2+ channels close and the open K+ channels keep the membrane potential at -90mV. This causes the resting potential in phase 4 of a cardiac myocyte action potential.
10006500
e
Outflow of K+
QuestionChoice
Ca2+ channels close, but the delayed K+ channels remain open and drop the membrane potential to -90mV. This causes the repolarisation in phase 3 of a cardiac myocyte action potential.
10006499
d
Outflow of K+ and inflow of Ca2+ stops
QuestionChoice
Transient K+ channels open and K+ outflow returns the membrane potential to 0mV as Na+ inflow stops. This causes partial depolarisation in phase 1 of a cardiac myocyte action potential.
10006497
b
Outflow of K+ and inflow of Na+ stops
Concept
Chapter
2693
3962
Cardiac Action Potential Generation and Conduction
Topic
159
Cardiovascular physiology
13846
What causes the rapid depolarisation in phase 0 of a cardiac myocyte action potential?
a