PHYSIOEX 9, ACTIVITY #3 Review Questions
1. Explain why increasing extracellular K+ reduces the net diffusion of K+ out the neuron through the K+ leak channels?
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?
3. Explain why a change in extracellular Na+ did not significantly alter the membrane potential in the resting neuron?
4. Discuss the relative permeability of the membrane to Na+ and K+ in a resting neuron.
5. Discuss how a change in Na+ or K+ conductance would affect the resting membrane potential. ACTIVITY #2
1. Sensory neurons have a resting potential based on the efflux of potassium ions (as demonstrated in Activity 1). What passive channels are likely found in the membrane of the olfactory receptor, in the membrane of the Pacinian corpuscle, and in the membrane of the free nerve ending?
2. What is meant by the term graded potential?
3. Identify which of the stimulus modalities induced the largest amplitude receptor potential in the Pacinian corpuscle. How well did the results compare with your prediction?
4. Identify which of the stimulus modalities induced the largest amplitude receptor potential in the olfactory receptors. How well did the results compare with your prediction?
5. The olfactory receptor also contains a membrane protein that recognizes isoamylacetate and, via several other molecules, transduces the odor stimulus into a receptor potential. Does the Pacinian corpuscle likely have this isoamylacetate receptor protein? Does the free nerve ending likely have this isoamylacetate receptor protein?
6. What type of sensory neuron would likely respond to the green light?
1. Define the term threshold as it applies to an action potential.
2. What change in membrane potential (depolarization or hyperpolarization) triggers an action potential?
3. How did the action...
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