Question

An action potential:

a) Is the main function of glial cells
b) Is initiated by a localized increase in membrane permeability
c) Is a graded potential, but bigger
d) Degrades as temperature increases
e) Propagates from axon terminals to axon hillocks

Answer 1

An action potential is initiated by a localized increase in membrane permeability to sodium ions and is an all-or-none electrical signal that propagates from the axon hillock towards the axon terminals.

Step-by-step explanation:

An action potential is a critical signal in the functioning of neurons. It is not the main function of glial cells, which are more so involved in supporting and maintaining neuronal function. Rather, an action potential is initiated by a localized increase in membrane permeability to ions, specifically sodium (Na+). An action potential is not a graded potential; it is an all-or-none response that, unlike graded potentials, does not vary in size but instead has a consistent amplitude when triggered.

Furthermore, an action potential does not degrade as temperature increases; in fact, increasing temperatures tend to increase the speed of action potential propagation up to a point, beyond which extreme temperatures can indeed be detrimental. Lastly, the propagation of an action potential is typically from the axon hillock towards the axon terminals, a direction known as anterograde conduction.