Discuss how a presynaptic neuron can stimulate the release o

Discuss how a presynaptic neuron can stimulate the release of neurotransmitter from a postsynaptic neuron.

Solution

Synapse is the junction between axon of one neuron and dendrite of another neuron. These neurons communicate with the help of chemical mediators called as “neurotransmitters.” The neuron above the synapse is called as “presynaptic neurone,” and the neurone below the synapse is called as “post synaptic neurone.”

The junction between the nerve terminal (axonal terminal) and the muscle fibre is called as “myoneural junction” or “neuromuscular junction.” At this site, the nerve does not contain myelin sheath and gets expanded, which contains the stores of acetyl choline (Ach), which act as a neurotransmitter at neuromuscular junction.

If the released neurotransmitter is excitatory and causes depolarization of post synaptic membrane, then EPSP (excitatory post synaptic potential) is generated. An EPSP triggers the action potential generation and allows the transmission of the impulse to the post synaptic neuron or an organ.

If the released neurotransmitter is inhibitory and causes hyperpolarisation of post synaptic membrane, then IPSP (inhibitory post synaptic potential) is generated. An IPSP inhibits the action potential generation and does not allow the transmission of the impulse to the post synaptic neuron or an organ.