Question

The release of a chemical messenger from synaptic vesicles is under the influence of _______ ion(s).

• A. (A) Cl−
• B. (B) Fe++and S++
• C. (C) Ca++
• D. (D) Mg++ and Sr++

Answer 1

Answer: (C)

(C) Ca++

Answer 2

Explanation:
The release of a chemical messenger from synaptic vesicles is under the influence of Ca++ ion(s).When an impulse arrives at the synaptic knob of the axon, it depolarizes the presynaptic membrane and increases its permeability to calcium ions (Ca2+).Ca2+ ions from the synaptic cleft pass into the synaptic knob via voltage-gated channels. Sudden rise in the cytosolic concentration of Ca2+, causes the release of a chemical, called neurotransmitter substance, from small synaptic vesicles present there into the synaptic cleft by exocytosis through the presynaptic membrane.Hence, the correct option is (C).