Botulinum toxin, or "botox", has become popular for cosmetic surgery. The toxin prevents neurosecretory vesicles from docking at the plasma membrane and releasing neurotransmitter. How would this toxin affect the neuromuscular junction?

Question

A.  Since ACh is not released, the muscles stay in a state of repeated contraction.
B.  Since ACh is not released, the muscles are not activated to contract and remain relaxed.
C.  Buildup of ACh causes promiscuous activation of all nearby sensory neurons.
D.  Buildup of ACh leaks back into the brain, creating a calming effect.

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?

Gather Content/Choose Answer
· What do you already know about the botulism? What other information is related to the question?

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

B.  Since ACh is not released, the muscles are not activated to contract and remain relaxed.

Clarify Question
· What is the key concept addressed by the question?
        o How does botulinum toxin affect the neuromuscular junction?
· What type of thinking is required?
        o This is an analyze question because you need to take information about the neuromuscular junction and synaptic transmission and predict clinical symptoms from a toxin.

Gather Content/Choose Answer
· What do you already know about the botulism? What other information is related to the question?
        o To solve this problem, you’ll need to know that ACh is released at neuromuscular junctions and that for a muscle cell to be activated and contract, ACh must be released by synaptic vesicles as they fuse to the pre-synaptic membrane, and then bind to ACh receptors in the post-synaptic membrane.

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o If you figured out the correct answer, good job! If not, where did you go wrong? Did you forget that neurotransmitter release at the neuromuscular junction is necessary for muscle contraction? Did you think that ACh affected all sensory neurons (answer C)? The question asked specifically about the neuromuscular junction, so you could eliminate answers C & D as they ask about sensory neurons and the brain in general.