Nervous MCQ explained

Nervous System:

Qn6: This is akin to question 19. If the sodium-potassium pump is not working, the new RMP will go towards zero/near zero – a value achieved when sodium and potassium ions are allowed to diffuse down its electrochemical gradient to reach its own equilibrium potential.

The initial RMP is already at -70mV. So to get to 0mV, it is largely determined by the influx of sodium channels and the speed at which the RMP gets to zero is impeded by the relatively low permeability of membrane to sodium ions (less leak channels).


Qn: I thought sodium-potassium pump does not contribute to the establishment of RMP?

Alternatively we mean: why is RMP at a particular value?

And that is primarily due to the differential permeability of the membrane to different ions which can readily influence the RMP values.
The pump may not contribute to the establishment of the RMP but it plays a role in the maintenance of it so that each ion cannot reach its own equilibrium potential by maintaining the relative concentration of each ion across the membrane.


Qn 19, no ATP -> sodium-potassium pump will not work. The new RMP is achieved mainly due to the influx of Na+ (since K+ is already pretty near to its equilibrium potential) and so the outside is now less positive.

Qn 20: acetylcholine: non-proteineous; an ester (of acetic acid and choline) – it is not a steroid and choline is an amine.