Question

if you were able to record the actual resting membrane potential of a single cell in this nerve would you see a normal resting potential? why or why not?

how is an action potential propagated down the axon? include when each channel opens.

Thank you!

Answer 1

An actual resting membrane potential of a cell is at -70mV in which the inside of the cell is more negative. In this case, there is no net movement of the ions inside and outside of the cell. The actual resting membrane potential of the cell is very important as it enables the cell to function well and helps in transmission of the signals from cell to cell. Hence, when the actual resting membrane potential is measured or is recorded, it would help in seeing the normal resting potential. This is because when the cell is at its actual resting membrane potential, it maintains a -70mV negative charge inside the cell and is the normal resting potential of the cell.

The action potential is a process by which neurons communicate with each other and this is triggered when it propagates an electrical signal. The action potential starts when the channel opens for Na+ ions and as the concentration of the Na+ is higher on the outside as compared to the inside, it will lead to rushing of the Na+ inside the membrane due to the difference in the concentration gradient. Since the Na+ is positively charged, it will change the voltage inside the cell and hence it will make the inside of the cell less negative. This is the depolarization state and hence in this the membrane potential moves towards zero.

The concentration gradient for Na+ will continue and hence the Na+ will enter the cells even when the membrane potential becomes zero. This would make the cell and voltage around it to become zero. This will make the membrane potential +30mV as the Na+ ions continue to enter. After this it will lead to the opening of the K+ ion channels and K+ ion will leave the inside of the cell to the outside, the membrane potential goes back to its resting potential which is called repolarization and hence the membrane potential again become –70mV and turns into resting membrane potential. After this there is a hyperpolarization which occurs when the K+ ions are still open and as they are slightly delayed in closing, this is a period of hyperpolarization.