8A) In a contractile ventricular cardiomyocyte, the depolarization phase of an A
ID: 3515916 • Letter: 8
Question
8A) In a contractile ventricular cardiomyocyte, the depolarization phase of an AP (before the plateau phase), is contributed to by:
a) Many Na+ ion channels opening/open
b) Many K+ channels closing/closed
c) Most Na+ ion and K+ channels are open
d) Most Na+ ion and K+ channels are closed
e) Most Na+ and Ca+ channels are open, and most K+ channels closed
f) Most Na+ and K+ channels are open, and most Ca+ channels closed
g) Most K+ and Ca+ channels are open, and most Na+ channels closed
8b) Redo this question but for “During the Middle of the Plateau phase” and answer WHICH ion/s has/have relatively high permeability?
a) Na+ b) Ca+ c) K+
8c) Redo this question but for “During the repolarization phase” and answer WHICH ion/s has/have relatively high permeability?
a) Na+ b) Ca+ c) K+
Explanation / Answer
8a. A) MANY NA + IONS CHANNELS OPENING/OPEN
( when the action potential reaches ventricular cells from adjacent cells fast NA+ channels get activated one by one causing increased flow of NA+ increasing the voltage within the cells. After threshold potential is reached large amount of NA+ influx occurs )
8b . B) CA+
( increased membrane permeability to calcium maintains the depolarised state and prolongs action potential )
8c. C) K+
( an inward potassium current produces produces repolarisation )
{ hope the answer is clear to you and if it was helpful please provide feedback. thank you }
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