An investigator places an isolated neuron in a calcium-free medium, gives the neuron a suprathreshold stimulus and then performs an assay to test whether neurotransmitter is released into the medium.Which of the following outcomes would you predict ?

Options

A. No neurotransmitter is detected since influx of calcium into the synaptic knob is required for neurotransmitter release.
B. No neurotransmitter is detected since influx of calcium is required in order for the neurons to conduct an action potential
C. Neurotransmitters is detected since calcium is not required for action potential coduction and the initial stimulus was suprathreshold
D. We cannot predict the outcome without knowing whether the neuron was myelinated or not

Answer

A

Explanation

Calcium ions are required for the transmission of nerve impulse at a chemical synapse.When an impulse arrives at a pre-synaptic knob, calcium ions from the synaptic cleft enter the cytoplasm of the pre-synaptic knob.The calcium ions cause the movement of synaptic vesicles to the surface of the knob.The synaptic vessels are fused with the pre-synaptic membrane and get ruptured to discharge neurotransmitters into the synaptic cleft.