GABA and glycine activate ionotropic channels that conduct chloride. How does the chloride conductance inhibit excitation? Select all that apply.
A) It lowers the voltage across the membrane to below action potential threshold.
B) It blocks activation of the excitatory receptor.
C) It provides an increased resistance in the membrane, making it more difficult to depolarize the voltage across the membrane.
D) It provides increased conductance in the membrane, making it more difficult to depolarize the voltage across the membrane.

Question

Quizplus · Accepted Answer

The chloride reversal potential is usually below the action potential threshold, so a high conductance to chloride will 'clamp' the voltage across the membrane to a potential below the action potential threshold. Because chloride channels open there is a large increase in the 'leakiness' of the membrane, which shunts current through other 'resistors' and decreases the effectiveness of any other depolarization of the membrane. Chloride does not block receptors. Opening channels decreases resistance and increases conductance, so choice

GABA and Glycine Activate Ionotropic Channels That Conduct Chloride