Question

Release of chemical messenger from synaptic vesicles is triggered by

• A. $M{g}^{2+},S{r}^{2+}$
• B. Fe, S
• C. Cl
• D. C$a^{2+}$

Answer 1

The correct option is D C$a^{2+}$

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 answer is (D)