Question

The amount of neurotransmitter released from the presynaptic cell is a function of
A. The voltage of the individual action potential in the presynaptic neuron
B. The frequency of the arriving action potential in the presynaptic neuron
C. Whether the action potential is excitatory or inhibitory
D. The receptors in the postsynaptic neuron

Answer 1

Hint: The nerve impulses are transmitted from one neuron to another through a neuromuscular junction or synapse. The membranes of a presynaptic neuron and a postsynaptic neuron forms the synapse. Presynaptic and postsynaptic membranes are those membranes which transmits and receives the nerve impulses respectively. The two membranes may or may not be separated by a gap called synaptic cleft. At the end of each axon, synaptic knobs are present which contain the neurotransmitters.

Complete Step by Step Answer:
The transmission of nerve impulses at these synapsis occurs through certain chemicals called neurotransmitters. These are present in the synaptic vesicles of the synaptic knob present at the axon terminal. Ther nerve impulses are taken up by the dendrites and are pushed into the cell body and axon. When these impulses (action potential) reach the axon terminal, the synaptic vesicles get stimulated to move towards the membrane and fuse with the plasma membrane and release the neurotransmitters into the synaptic cleft.

The release of these neurotransmitters depend upon the frequency of action potential. So if the frequency of the action potential reaches the presynaptic neuron, the amount of neurotransmitter released will also increase. Receptors are present on the postsynaptic membrane that binds with the neurotransmitter released and opens ion channels that allows the entry of ions which can generate a new action potential in the postsynaptic neuron (can be excitatory or inhibitory).

Thus, the correct answer is option B:- the frequency of the arriving action potential in the presynaptic neuron.

Note: Our nervous system consists of more than 40 neurotransmitters. Some of the important ones are Acetylcholine, dopamine, histamine, glutamate and serotonin etc.