Describe the ionic basis of an action potential and be sure to include the role of...

Describe the ionic basis of an action potential and be sure to include the role of channels/gates within the cell membrane and how this relates to a positive feedback homeostatic mechanism.

Expert Solution

There are many ion channels/gates located in the membrane. Some of it allows free movement while some need ATPs for their actions.

When a neuron is not conducting any impulse, i.e, resting, axonal membrane is comparatively more permeable to K+ ions and nearly impermeable to Na+ ions. The membrane is impermeable to negatively charged proteins too.

Consequently, the axoplasm inside the axon contains high concentration of K+ ions and low concentration of Na+ ions. In contrast, fluid outside the axon contains low K+ and high Na+ ions and thus form a concentration gradient.

These ionic gradient are maintained by NA+/K+ ATP pump. It pumps 3Na+ outwards and 2K+ into the cell. As a result, outer surface possess a positive charge while its inner surface are negatively charged and therefore polarised. The electrical potential difference across the resting plasma membrane is called as the RESTING POTENTIAL.

In neuron signalling, the cycle of rapid depolymerization during the action potential is positive feedback loop.

gladiator answered 1 year ago

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