After the effector cell has been stimulated by acetylcholine (ACh), what enzyme stops this stimulation and allows the effector membrane to repolarize?

A) Decarboxylase

B) Norepinephrine

C) Acetylcholinesterase

D) Catecholamine

The correct answer is C) Acetylcholinesterase.

Explanation:

Neurotransmitter release occurs in the neuron axon. The sending neuron has vesicles filled with neurotransmitters in their interior. When an action potential reaches the nervous terminal or the varicosities, it causes the neurotransmitter release by exocytose forward to the synaptic space. The molecule binds to its receptor in the postsynaptic neuron. This receptor is a protein structure that triggers an answer. As long as the acetylcholine is in the synaptic space, it keeps linking to its receptor and causing a postsynaptic answer. To stop this process, the neurotransmitter must be taken out from the synaptic space. There are two mechanisms by which the neurotransmitter can be eliminated:

Enzymatic degradation/deactivation: In the synaptic space, there is a specific enzyme called Acetylcholinesterase that can inactivate the neurotransmitter by breaking or degrading it. In this case, the new molecule won't be able to bind to the neurotransmitter receptor. Reuptake: There are receptors located in the presynaptic membrane that can capture de molecule to store it back in new vesicles, for posterior use.