Question

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

• (A) ${\mathrm{Cl}}^{-}$
• (B) ${\mathrm{Fe}}^{++}$and ${\mathrm{S}}^{++}$
• (C) ${\mathrm{Ca}}^{++}$
• (D) ${\mathrm{Mg}}^{++}$ and ${\mathrm{Sr}}^{++}$

Answer 1

The Correct Option is C

Explanation:
The release of a chemical messenger from synaptic vesicles is under the influence of ${\mathrm{Ca}}^{++}$ 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 $\left({\mathrm{Ca}}^{2+}\right).{\mathrm{Ca}}^{2+}$ ions from the synaptic cleft pass into the synaptic knob via voltage-gated channels. Sudden rise in the cytosolic concentration of ${\mathrm{Ca}}^{2+}$, 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).