Question

When the stimulus voltage was increased from 30 mV to 50 mV, what happened to the peak value of the action potential?

a) it increased proportionally, that is, it also doubled

b) it decreased to one-half its peak value
c)it increased slightly
d)there wasn’t any change

Answer 1

Answer: Option d- there was not any change

Action potentials follow All or None phenomenon.

Normally the cells have resting membrane potential. When an stimulus with suffficient voltage -THRESHOLD stimulus is applied, it causes an action potential, When the strength of stimulus is less than threshold stimulus, no action potential develops.When the strength of stimulus is more than threshold stimulus, action potential develops.

As the strength of stimus is increased, more and more cells are recruited and the frequency of action potentials developed increases ( frequency of firing is proportional to the magnitude of stimulus) -resulting in increase in action potential developed