twesting2173
Forum Senior
Topics: 7
Posts: 65
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i think it's c. a is the rush of na into the cell, b is where the k channel opens and starts to repolarize, but then....quick, ca channels open and the ca goes into the cell giving us the palteau phase that is unique to cardiac muscle. let me know if you agree.
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| star1
Forum Guru
Topics: 93
Posts: 826
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During which phase of the ventricular action potential shown does norepinephrine influence the influx of Ca2+?
A= Na influx
B= Na influx stop
C= Ca influx+ K outflux >>>> balance each other so a platue phase
D= Ca influx stop , K outflux at its peak
E= only state which is permeable to K
so Noreponephrine will affect only C when we are talking about Ca
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| Musuq
Forum Guru
Topics: 103
Posts: 425
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C)
I would also go for C) because NE acting on its Beta receptor in the heart, is more related to Ca++ channels' effects
and the conductance of Calcium is high in phase 2 of the cardiac action potential, so I think that this would be the phase in the cardiac action pot, affected by Norepinephrine
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| klimt
Forum Guru
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Posts: 605
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yes it's C
and great pictures Musuq
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| ManuNastai
Transilvanian..
Topics: 55
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i'd go with D 'cause that's when the relative refractory period of the cell is and that's the moment when you stimulate the sympathetic (NE) you get a depolarization (Ca++ influx) leading to tahicardia
how sure are you Musuq on your responses?
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| tran6996
Forum Newbie
Topics: 4
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how could it be D ? when K efflux and closure of Ca channel occur ?
answer is C
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| vallia
Forum Guru
Topics: 98
Posts: 889
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C
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