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M03_ZAO2177_01_SE_CH03.QXD

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R E V I E W

S H E E T
EXERCISE

3

NAME_________________________________ LAB TIME/DATE ________________________

Neurophysiology of Nerve Impulses

A C T I V I T Y

1

The Resting Membrane Potential

1. Explain why increasing extracellular K reduces the net diffusion of K out of 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 prediction? ___________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ 3. Explain why a change in extracellular Na did not 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. ______________________ __________________________________________________________________________________________________ A C T I V I T Y 2

Receptor Potential

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? ______________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ 51

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Review Sheet 3

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 isoamyl acetate and, via several other molecules, transduces the odor stimulus into a receptor potential. Does the Pacinian corpuscle likely have this isoamyl acetate receptor protein? Does the free nerve ending likely have this isoamyl acetate receptor protein? _____________________________ __________________________________________________________________________________________________ 6. What type of sensory neuron would likely respond to a green light? ___________________________________________...
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