Question

Potassium channels open first following stimulation leading to an action potential

Select one:

True

False

The concentration of sodium ions are highest in the cytoplasm of neurons

Select one:

True

False

Answer 1

1) Potassium channels open first following stimulation leading to an action potential.

FALSE

First the sodium channels open following stimulation. This opening of sodium channels will lead to entry/influx of sodium ions (Na+) into the cell making the membrane potential more positive.

Depolarization of the plasma membrane due to opening of gated Na+ channels. This depolarization causes Action potential after crossing the threshold level.

Opening of potassium channels causes efflux of K+ outside the cell. This will make the membrane potential more negative and thus causes repolarisation.

So the above statement is false.

2) The concentration of sodium ions are highest in the cytoplasm of neuron :-

FALSE

The inside of the cell has a low concentration of sodium ions, and the outside of the cell has a higher concentration of sodium ions.

The concentration of sodium is higher on the outside of the cell and low concentration on the inside of the cell because the cell has low permeability to sodium than potassium so the high concentration of (Na+) outside the cell pushes this ion into the cell down the concentration gradient.

Thus the above statement is false that concentration of concentration of sodium ions are highest in the cytoplasm of neurons.