College of Massage Therapists of British Columbia (CMTBC) Practice Exam

What occurs when there is a lack of acetylcholinesterase in the synaptic vesicles?

1. Muscle atrophy

2. Spastic paralysis - continuous stimulation with muscles unable to relax

3. Reduced pain sensation

4. Increased flexibility

The correct answer is: Spastic paralysis - continuous stimulation with muscles unable to relax

When there is a lack of acetylcholinesterase in the synaptic cleft, the enzyme responsible for breaking down the neurotransmitter acetylcholine, there is prolonged stimulation of the postsynaptic receptors. Normally, acetylcholine is released from the presynaptic neuron and binds to receptors on the muscle cell's membrane, leading to muscle contraction. If acetylcholinesterase is absent or insufficient, acetylcholine does not get cleared from the synaptic cleft, resulting in continuous stimulation of the muscle fibers. This condition leads to spastic paralysis, where the muscles remain in a contracted state and are unable to relax. The excess presence of acetylcholine keeps activating the muscle fibers, preventing normal muscle function, including relaxation. This excessive and prolonged contraction can result in symptoms such as stiffness and spasms in the affected muscles. The other options lack alignment with the physiological consequences of acetylcholine accumulation. Muscle atrophy is more related to disuse or nerve damage rather than neuromuscular transmission failure. Reduced pain sensation and increased flexibility are not direct results of acetylcholine inactivity; they do not describe the effects of neurotransmitter dysregulation in the context of muscular function.