JCU Anatomy Quiz 2

Identify the part of neuron labeled as 1

Identify the part of neuron labeled as 4

Identify the part of neuron labeled as 3

Identify the part of neuron labeled as 5

Identify the part of neuron labeled as 6

Identify the part of neuron labeled as 2

The graph above shows how the membrane potential of a given point inside an axon changes over the course of an action potential. (Terms may be used more than once!) A. Resting state: all voltage-gated channels are closed, but _______ channels are open.

B. _______ phase: _______ channels open as the membrane is depolarized by a local graded potential. This increases the permeability of _______ ions drastically and makes the cell interior more positive. Once the membrane potential has reached a level called the _______ (shown as line O), depolarization becomes self generating and an action potential has been formed.

C. _______ phase: _______ channels inactivate and _______ channels open. _______ ions rush out of the cell, following the electrochemical gradient. This causes the cell interior to become more negative.

D. _______ phase: _______ channels remain open longer than needed to restore the resting membrane potential, causing the membrane potential to be more negative than the resting membrane potential. The _______ channels close soon after. The ion distribution has changed and is reset by the _______ pumps.