Week 05 Assignment

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Week 05 Assignment 1. Gated channels that open or close in response to a change in the transmembrane potential are a. mechanically regulated channels b. voltage regulated channels c. chemically regulated channels d. all options are correct Ans: B 2. Changes in transmembrane potential that are not restricted to the area surrounding the site of simulation are a. action potentials b. graded potentials c. inhibitory potentials d. hyperpolarizing potentials Ans: A 3. The synapsing of several neurons on the same postsynaptic neuron is a. serial processing b. reverberation c. divergence d. convergence Ans: D 4. If the resting membrane potential is -70mV and the threshold is -55mV, a membrane potential of -60mV will a. produce an action potential b. make it easier to produce an action potential c. make it harder to produce an action potential d. hyperpolarize the membrane Ans: B 5. A graded potential a. decrease with distance from the point of stimulation b. spreads passively because of local currents c. may involve either depolarization or hyperpolarization d. all options are correct Ans: D 6. For an action potential to begin, an area of excitable membrane must a. have its voltage-regulated gates inactivated b. be hyperpolarized c. be depolarized to threshold level d. not be in relative refractory period Ans: C 7. During an absolute refractory period, the membrane a. continues to hyperpolarize b. cannot respond to further stimulation c. can respond to a larger-than-normal depolarizing stimulus d. will respond to summated stimulation Ans: B 8. Action potentials are restricted to areas of excitable membranes that contain voltage regulate channels a. true b. false c. action potential and voltage regulated channels are not related to each other d. only for some cases it is true Ans :A 9. The all or none principle state that a. the properties of an action potential are independent of the strength of the depolarizing stimulus b. all stimuli will produce action potentials c. all graded potentials will generate action potentials d. if stimulated to threshold, any cell membrane can generate and propagate an action potential Ans: A 10 The loss of positive ions from the interior of a neuron produces a. depolarization b. threshold c. hyperpolarization d. an action potential Ans: C .

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