Question

Considering the nervous system.

I. What is the normal value of the resting membrane potential of a neuron?

How does sodium pump do to maintain the resting membrane potential? Is it an active or a passive process?

Briefly describe how ions moving across the plasma membrane can generate an action potential in a neuron.

Besides nervous tissue, state ONE specialized type of tissue that is able to generate action potentials.

Answer 1

1) The normal value of the resting membrane potential of a neuron is approximately -70 mV.

Resting membrane potential is the voltage difference across the cell membrane when the cell is at rest.

2) The Na+/K+ pump creates a concentration gradient by moving 3 sodium ion out of the cell and 2 potassium ion into the cell.The pump continues to move Na+ out of the cell even when more Na+ ions are present there.So Na+ is being pumped against their concentration gradient.In this way it maintains the resting membrane potential.It is an active process as ions are pumped against their concentration.

3)Ion channels are present on the plasma membrane of neuron.These channels are shut when the membrane potential is near the resting potential of the cell but they rapidly begin to open if the membrane potential increases to threshold voltage and ions move into the cell.This causes depolarisation.Again repolarisation occurs when ions move out of the cell creating a change in polarity between outside and inside of the cell.Thus continuous depolarisation and repolarisation can generate an action potential in a neuron

4) Besides nervous tissue, Cardiac tissue is able to generate action potential.