Question

Why is it important to rid a synaptic cleft of neurotransmitter, and what are 3 ways in which this can happen?

Answer 1

The presence of a neurotransmitter in the synaptic cleft leads to the continuous activation of the post-synaptic neuron. So, the signal must be turned off by removing the neurotransmitter. This is to ensure the brief and localized action.

For the signal to be terminated, first, the neurotransmitter must be released from the receptor followed by its removal from the synaptic cleft.

The removal of neurotransmitter can occur by three mechanisms:

i. Enzymatic degradation: Most of the neurotransmitter is degraded by the Acetylcholinesterase enzyme.

ii. Reuptake by presynaptic neuron: The presynaptic neuron can reuptake the neurotransmitter in an active process. Ex: NET and SERT.

iii. Diffusion into the surrounding tissue: A small fraction of the neurotransmitter is passively diffused into the surrounding tissue and becomes unavailable.