Question

What determines whether a neuron initiates an action potential? Include the role of resting membrane potential, threshold, sodium, graded potentials, and the axon hillock. (ANSWER MUST BE IN SHORT ANSWER PARAGRAPH FORM)

Answer 1

The action potential will be initiated or not depends on the presence or absence of electrical gradients (graded potential) across the neuron membrane. For initiation of action there has to presence of difference in Ionic concentration across the membrane. Generally during resting membranes potential, three sodium ions moves out and 2 potassium ion comes inside cell membrane. But when sodium ion concentration reaches above threshold, the concentration of sodium increases outside the cell. This cause rapid influx of sodium into the cell and action potential propogates in the neuron starting from dendrites and passing through axon hillock to ultimately reach axon terminal. Axon hillock is a control point which decide whether the action potential will propagate or not