Question

In an experiment, the membrane potential of a neuron is hyperpolarized to –120 mV. When an inhibitory neurotransmitter is applied to the preparation, the membrane is depolarized. Which of the following could explain this result?
a. Inhibitory transmitters normally depolarize the synaptic membrane.
b. The normal response of the postsynaptic membrane to any transmitter is depolarization.
c. The inhibitory transmitter activates ligand-gated potassium channels.
d. Sodium channels become inactivated.
e. Calcium channels become activated.

Answer 1

Answer:

The inhibitory transmitter activates ligand-gated potassium channels

Explanation:

When a cell is in hyperpolarized state,the potassium gated channels are taken longer time to close up, Therefore, more K+ leaks out of the axoplasm  to the exterior.Therefore the cell appears to continue in the resting state, with more negative value of the cell potential of (-120 mV) and this called hyperpolarization.

However, with the addition of  inhibitory transmitter,the ligand-gated potassium channels are activated,Theses channels closes up.Then sodium  gated channels, which  were initially in refractive state reopens, sodium ions diffuses inwards for depolarization, and the neuron returns to depolarized state.