Physioex 3 Essay

963 Words Jan 26th, 2013 4 Pages
ACTIVITY 1: THE RESTING MEMBRANE POTENTIAL
1. Explain why increasing extracellular K+ reduces the net diffusion of K+ out the neuron through the K+ leak channels?
When the diffusion is greater on one side, the other side will slow down.

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 predictions?
There are two potassium's for every sodium so the increase of potassium will make it more negative. Prediction was correct.

3. Explain why a change in extracellular Na+ did not alter the membrane potential in the resting neuron?
The sodium channels are mostly closed during the resting state.

4. Discuss the relative
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Does the Pacinian corpuscle likely have this isoamyl acetate receptor protein? Does the free nerve ending likely have this isoamylacetate receptor protein?
No

6. What type of sensory neuron would likely respond to the green light?
Physical sensory.

ACTIVITY 3: THE ACTION POTENTIAL: THRESHOLD
1. Define the term threshold as it applies to an action potential.

It is the transmembrane potential at which an action potential begins.
2. What change in membrane potential (depolarization or hyperpolarization) triggers an action potential?
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?
It did not change. Prediction incorrect.
4. An action potential is an "all-or-nothing" event. Explain what is meant by this phrase.
All stimuli that bring the membrane to threshold generate identical action potentials. The properties of the action potential are independent of the relative strength of depolarizing stimuli.
5. What part of a neuron was investigated in this activity?
The Axon.
ACTIVITY 4: THE ACTION POTENTIAL: IMPORTANCE OF VOLTAGE-GATED NA+ CHANNELS

1. What does TTX do to voltage-gated Na+ channels?
It irreversibly blocks voltage gated sodium channel in the

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