49. When a nerve impulse reaches the synaptic knobs of a neuron, calcium: a. is

Question

49. When a nerve impulse reaches the synaptic knobs of a neuron, calcium:

         a.     is pumped into the neuron & neurotransmitter diffuses out through channels.

         b.     is released from the neuron along with neurotransmitter from synaptic vesicles.

         c.     diffuses into the neuron & neurotransmitter is released by exocytosis.

         d.     & neurotransmitter diffuse into the synaptic knob.

         e.     is immediately pumped out of the neuron & vesicles of neurotransmitter undergo exocytosis.

Explanation / Answer

When a nerve impulse reaches the synaptic knobs of a neuron, calcium:

ANSWER- c. diffuses into the neuron & neurotransmitter is released by exocytosis.

EXPLANATION- Synaptic vesicles contain neurotransmitters. When an impulse reaches the synaptic knob, calcium diffuses into the neuron from the extracellular fluid, the calcium inside the synaptic knob causes the synaptic vesicles to fuse with the cell membrane which causes the release of the neurotransmitters by exocytosis.

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