Question

Which of the following processes is most important in the termination of the action of noradrenaline?

A) Reuptake into the presynaptic nerve terminal

B) Diffusion away from the synaptic cleft

C) Metabolism by monoamine oxidase (MAO)

D) Binding to autoreceptors

Answer 1

The most important process in terminating the action of noradrenaline is reuptake into the presynaptic nerve terminal, where it is transported back into the neuron, clearing the synapse and ensuring proper neurotransmitter balance.

Step-by-step explanation:

Among the options for terminating the action of noradrenaline, reuptake into the presynaptic nerve terminal is considered to be the most important. This process involves transporting noradrenaline back into the neuron that released it, which serves to clear the synapse for the next signal. Reuptake ensures a distinct "on" and "off" state between signals and maintains neurotransmitter balance. Although other mechanisms such as diffusion away from the synaptic cleft, metabolism by monoamine oxidase (MAO), and binding to autoreceptors also play roles in cessation of noradrenaline's action, reuptake is the primary means by which the neurotransmitter is removed from the synaptic cleft.