Chapter 7, Problem 5aCP

Summary Introduction

To review:

The following:

Explanation of all-or-none law of action potentials.

Effects of raised stimulus strength on action potential production.

Ways in which refractory periods exerts effect on the frequency of action potential production.

Introduction:

When a part of axon membrane gets depolarized, the positive feedback on sodium ion channel permeability makes the membrane potential increase above +30 millivolt. This slight increase does not move more than +30 millivolt as sodium ion channels tend to close quickly when the potassium ion channels open up. Hence, the size or amplitude of action potential becomes all-or-none. Moreover, action potentials are produced when stimulus of a prescribed intensity is steadily maintained at a particular point of axon.