Rachana
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in cardiac cells is due to what?
aacording to kaplan lecture notes, though the topic is controversial they assume it to be due to decreasing K conductance.
But according to some other source it is due to increase in Na.
I am confused.
Any inputs?
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| mjl1717
Forum Hero
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I always thought it was due to "high K permeability due to K channels
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| Rachana
Forum Junior
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I think I am talking abt phase 4 in SA node.
Would it still be K?
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| mash
Forum Fanatic
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it is decreased K conductance dat increases excitability
reason is dat SA node does not ve many Na channels
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| Rachana
Forum Junior
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Thanks Mash.
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| suvi21
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The Sa nodal diastolic depolarization (spontaneous depol) is due to three factors: 1) Decreased K conductance( This also contributes to their less negative resting membrane potential, i.e. because relative conductance of K to total ionic conductance is less, so it doesn't reach the nerst potential of K as other cells do). 2) Na conductance; this is a slow Na conduction through special channels called the "funny conduction channels", as they seem to be non-specific in their conduction. These are NOT the fast conducting Na channels found in ventricular muscle. 3) Ca conduction to some extent.
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