Question

what prevents acetylcholine (ach) from rebinding to a receptor and reopening the receptors channel?

a.) inactivation and degradation by acetylcholinesterase
b.) depolarization of the membrane potential of a muscle fiber
c.) spreading of the electrochemical signal along the sarcolemma
d.) diffusion across the synaptic cleft

Explanation:

Identify the mechanism of acetylcholine removal

Acetylcholine (ACh) released into the synaptic cleft must be rapidly removed or inactivated to prevent continuous stimulation of the postsynaptic receptors. The primary mechanism that prevents ACh from rebinding and reopening the receptor channels is its rapid enzymatic degradation.

Evaluate the role of acetylcholinesterase

The enzyme acetylcholinesterase (AChE) resides in the synaptic cleft and specifically breaks down acetylcholine into choline and acetate, thereby terminating the signal and preventing rebinding.

Answer:

• a.) Inactivation and degradation by acetylcholinesterase (Correct answer)
• b.) Depolarization of the membrane potential of a muscle fiber
• c.) Spreading of the electrochemical signal along the sarcolemma
• d.) Diffusion across the synaptic cleft