Question

certain scorpions produce a toxin that inhibits the na+ channel closing. now that you have identified the role of na+ channels in nerve cells, can you predict the effect of the scorpion toxin on neuronal function? remember that you can lower the labpad to take another look at the wall screen, or click the view image button to display that same image in the labpad.
a) hypo - excitability: more na+ flows into the cell, causing neurons not to fire as readily
b) less na+ is pumped out of the cell, slowing down return to the resting state
c) na+ is toxic to nerves
d) hyper - excitability: more na+ flows into the cell, causing neurons to fire more

Explanation:

When Na⁺ channel closing is inhibited, more Na⁺ flows into the neuron. This depolarizes the neuron more easily and frequently, leading to hyper - excitability as neurons fire more readily. Option a is incorrect as it describes hypo - excitability. Option b is about the sodium - potassium pump function which isn't the main effect here. Option c is incorrect as Na⁺ is not inherently toxic to nerves in normal physiological concentrations.

Answer:

d) Hyper - excitability: more Na⁺ flows into the cell, causing neurons to fire more