Question

why did the neuron's membrane potential go from -70 mv to -40 mv when you increase the extracellular concentration of potassium?

a) because this change cause less potassium to leave the neuron

b) because this change cause less calcium to enter the neuron

c) because this change cause a lot more sodium to enter the neuron

d) because this change caused a lot more potassium to leave the neuron

Answer 1

Opton c) because this change cause a lot more sodium to enter the neuron.

Normal resting membrane potential of a cell is about -70 mV.This is because Inside of the cell contains more Anions like cl- and Some potassium.Outside of the cell Contains more Na+ ions.The concentration of Na+ ions outside the cell is more than Concentration of K+ Inside the cell.

So there is chance that Na+ ions enter the cell from outside(Na+ Concentration is high Outside and low inside).When you increase the extracellular concentration of potassium outside of the cell becomes more positively charged So that Na+ (Whose concentration was very high outside the cell) will enter the cell---- Due to the entry of this positive ions---Membrane potential changes from -70 to -40 mV