Question

Neurotransmitter released into the synaptic gap reaches the target cell by?

1) exocytosis
2) diffusion
3) muscle contraction
4) conduction down the axon

Answer 1

The neurotransmitter reaches the target cell by diffusion (option 2) after being released into the synaptic cleft through exocytosis from the presynaptic neuron's axon terminal.

Step-by-step explanation:

The neurotransmitter released into the synaptic gap reaches the target cell primarily by diffusion. When an action potential travels down the motor neuron's axon to the axon terminal, voltage-gated Ca2+ channels open and allow Ca2+ ions to enter.

These ions facilitate the merging of neurotransmitter-containing synaptic vesicles with the presynaptic membrane, resulting in neurotransmitter release through exocytosis into the synaptic cleft. Once released, the neurotransmitter diffuses across the synaptic cleft and binds to ligand-gated ion channels on the postsynaptic membrane, which can lead to further propagation of the nerve impulse in the next cell or result in a muscle contraction when the cell is part of a muscle fiber.