Question

Sumer has come up with a great analogy for a presentation she is giving in her psychology class. The membrane encasing a neuron only allows some ions to pass in and out of its channels. And she is going to describe this _____ membrane as a guard only allowing some patrons to enter and leave a controlled area.

Answer 1

Answer:

Cell membrane

Explanation:

Sumer has come up with a great analogy for a presentation she is giving in her psychology class. The membrane encasing a neuron only allows some ions to pass in and out of its channels. And she is going to describe this cell membrane as a guard only allowing some patrons to enter and leave a controlled area.

Answer 2

Answer:

Cell surface membrane.(Axolemma)

Explanation:

These membranes encasing the neuron is perforated by ion channels,  which allow   diffusion of ions  with their charges across it down their electrochemical gradients. These ion channels are specific to a particular ion, while restricting others. E,g sodium-potassium pump , are special ion channels  in  axon cell membrane with specif channels for sodium ions, and will not allow the passage of potassium through the same channels and vice-versa.

There are two types on these ion  channels based on  what controls their openings.

The voltage gated ion channels which are controlled by the electrical potential or  voltage generated across the axon.And the ion channels control by the electrochemical gradients of the ions moving across the membrane.

The reversal of the charges of these ions across it (axonlemma)  create membrane potential down the length of the membrane. This set up a voltage change inside the Axoplasm(cytoplasm of the axon). If this voltage  is  up to the threshold it creates depolarization of the ( ion channels)with influx of sodium ions, while the potassium ions channels are shut up.

Furthermore, if the stimulation of the neuron is intense, and the membrane potential  increases up to the threshold level   the electrical potential energy generated cause the (voltage gated channels to open) . The potential generated is called Action potential.

Summary

The specificity of these channels to certain ions while restricting others  is a good illustration for Sumer to   describe how a guard can control the movement of patrons in a controlled area.