What is Quantal Release of Neurotransmitter

Question

What is quantal release of neurotransmitter?
A) Release of neurotransmitter in discrete units
B) Release of one neurotransmitter molecule at a time
C) Release of transmitter onto extrasynaptic receptors

Accepted Answer

is correct. Most neurotransmitters are released in discrete units or packets. Graded release of neurotransmitter with a graded change in the presynaptic membrane (like in the retina). Neurotransmitters are packaged and released from vesicles, so (c) is not correct. Although extrasynaptic transmitter release is probably quantal, this is not the correct answer.