Question

steps that occur at a chemical synapse. Describe in detail all of the steps of an action potential (you can describe this in words only, a drawing with descriptive words or both). Also, describe the difference between absolute and relative refractory periods and discuss when during the action potential each takes place.

Answer 1

The cell membrane is negatively charged from inside and positively charged from outside before the generation of action potential. After the stimulus, the channels in the membrane opens up that allow the diffusion of sodium into the cell that decreases the negativity of the membrane. If the local potential reaches to about threshold potentrial that is -60mV than all the sodium channels open, and sodium diffuses rapidly in the cell that changes the polarity and depolarizes the membrane and generate action potential at +55mV. And it is then transmitted to the adjacent nurons through depolarization.

Absolute refractory period is the period thta overlaps the depolarization and around 2/3 of repolarization phase. A new action potential cannot be created because all of the voltage gated channels are already opened. Absolute refractory period ends when enouigh sodium channels recover from their inactive state.

Relative refarctory period is the period when there is possibility of generating the new action potential. But only on the suprathreshold stimulus. This overlaps the final 1/3 of repolarization.