19. Identify the two major types of channels that open and close during an action potential in a neuron (see images below). the voltage-gated Na* channel and the voltage-gated Kichannel

42. List and explain the features that lead to the differences in nerve impulse conductance in a bare plasma membrane versus an unmyelinated axon versus a myelinated axon.

13) Draw a graph representing the changes in membrane potential across the axonal membrane before, during, and after an action potential. On your graph, use a highlighter to clearly indicate for which portions of your graph the letter corresponding to each cellular event listed below belongs. List of cellular events: A) All K* channels open B) All Na* channels close C) The Na*/K* ATPase cotransporter transports Na* and K* across the membrane. D) All Na* channels open E) The threshold value of membrane potential is attained. F) All K* channels close G) Some Na* channels open Your graph:

A membrane potential (Vm) labeled axis on the graph In the graph draw the phases of the action potential Include the channels involved and when they open and close matching them to the Vm Indicate the periods in which the action potential can or cannot occur