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Old 07-24-2012
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Default what defines the threshold potential?

hello..i am having difficulties when learning about the membrane potential..

1.if kalium and sodium define the resting membrane potential ,then... what defines the threshold potential?

2. what is the relation between calcium and sodium? because it was said that if we have hypocalcemia then it will bring the potential closer to threshold..why?

3. in the picture ,we will have a peak of action potential +30 mV to produce a contraction..my question is..how about if we have a peak of action potential less than the +30 will it cause weaker contraction? thx u


regards, Jean
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Old 08-06-2012
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Default what determines threshold potential

Threshold potential is caused by a net inward current larger than the net outward current.Thus the balance between the Na conduction and K conduction determines the threshold potential.
Action potential is produced only once the threshold potential is crossed as it an all or none phenomenon and hence the depolarisation is sustained once the threshold is crossed and either an impulse is generated or muscle contraction occurs.
I only know that hypocalcemia raises the resting potential towards the threshold mech I am not aware .Hope my explanations are OK
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Old 08-07-2012
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Default thank you...

hi,preeti617..thx u for the answer , i appreciate it...but i still have confusion.. so, the sodium and the potassium defines both the resting membrane potential and threshold potential, but what sets the threshold potential value (at -50mV)?thx u also
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Old 08-07-2012
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Quote:
Originally Posted by jeansen View Post
hi,preeti617..thx u for the answer , i appreciate it...but i still have confusion.. so, the sodium and the potassium defines both the resting membrane potential and threshold potential, but what sets the threshold potential value (at -50mV)?thx u also
its just the factual value at which action potential start or voltage gated sodium channel will start to open
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