When the neurotransmitter diffuses across the synaptic cleft,
A) it automatically causes depolarization of the postsynaptic membrane.
B) it can be excitatory or inhibitory, depending on the type of postsynaptic membrane.
C) a single molecule is sufficient to trigger activation of the postsynaptic membrane.
D) only a few molecules make it to the postsynaptic membrane.
E) it must move through nodes in the myelin sheath.

Question

When the neurotransmitter diffuses across the synaptic cleft,
A) it automatically causes depolarization of the post­synaptic membrane.
B) it can be excitatory or inhibitory, depending on the type of postsynaptic membrane.
C) a single molecule is sufficient to trigger activation of the postsynaptic membrane.
D) only a few molecules make it to the postsynaptic membrane.
E) it must move through nodes in the myelin sheath.

Quizplus · Accepted Answer

The effect of a neurotransmitter on the post-synaptic membrane can either be excitatory (causing depolarization) or inhibitory (causing hyperpolarization) depending on the type of receptor present on the membrane. Therefore, option B is the correct answer. Option A and C are incorrect as the activation of post-synaptic membrane depends on the amount of neurotransmitter binding to receptors and the threshold required for activation. Option D is incorrect as multiple molecules of neurotransmitter are required to cause an effect on the post-synaptic membrane. Option E is incorrect as the myelin sheath is only present in certain neurons and is not involved in synaptic transmission.

When the Neurotransmitter Diffuses Across the Synaptic Cleft