Ionic Basis of the Action Potential Flashcards
At resting potential, what is the sodium concentration inside and outside of the axon?
140mM out and 10mM in.
At resting potential, what is the concentration of potassium inside and outside of the axon?
5mM outside and 140mM inside.
At rest, what ions are cells more permeable to?
Potassium- resulting in a net efflux of potassium ions.
Do Na+ move into the cell at resting potential?
Yes, but 50 times less than potassium efflux.
What is Ohm’s law?
V=IR.
What must the initial depolarisation reach?
A critical threshold.
What happens once the threshold is attained?
The depolarising upstroke is regenerative.
When does the depolarisation peak?
+30mV.
How can you describe the action potential response?
All or nothing.
What happens after the action potential has occurred?
The potential repolarises from the peak of the overshoot back to the resting level.
What is upstroke associated to?
A rapid increase in sodium permeability (x600).
What is repolarisation associated with?
A delayed 10 fold increase in the permeability to potassium.
What is the approximate resting potential?
-70mV.
When are voltage-gated potassium channels closed?
At resting potential, delayed opening triggered at threshold, remains closed to peak potential.
When are voltage-gated potassium channels open?
From peak potential through after hyperpolarization.
