Physio Ex

Physio Ex- Excersise 3

Activity 1

1.) Explain why increasing extracellular K+ reduces the net diffusion of K+ out of the neuron through the K+ leak channels.

Increasing the extracellular K+ reduces the steepness of the concentration gradient and resulting in less K+ diffusing out of the neuron.

2.) Explain why increasing extracellular K+ causes the membrane potential to change to a less negative value. How well did the results compare with your prediction?

The membrane potential became less negative because less K+ diffused out so if more K+ stays in it is more positive or less negative. This matched my prediction

3.) Explain why a change in extracellular Na+ did not alter the membrane potential in the resting neuron.

The change in extracellular Na+ didn’t change the membrane potential because there was more K+ leakage channels open then Na+ leak channels.

4.) Discuss the relative permeability of the membrane to Na+ and K+ in a resting neuron.

The relative permeability of sodium is low because of the fact there is few sodium leak channels.

5.) Discuss how a change in Na+ or K+ conductance would affect the resting membrane potential.

A change in K+ conductance would have a greater effect on the resting membrane potential than a change in Na+ conductance would because there are more K+ leak channels then Na+

Activity 3

1.) Define the term threshold as it applies to an action potential.

The threshold is the voltage when you can first see action potential occurring.

2.) What change in membrane potential (depolarization or hyperpolarization) triggers an action potential?

The change in membrane potential that triggers an action potential is depolarization.

3.) How did the action potential at R1 (or R2) change as you increased the stimulus voltage above the threshold voltage? How well did the results compare with your prediction?

The action potential did not change which was opposite of my prediction.

4.) An action potential is an “all-or-nothing”...