Sarin gas is an inhibitor of an enzyme that functions in the neuromuscular junction to break down acetylcholine. What is the most likely description of how a person would die after inhaling this poisonous gas?

Question

A.  suffocation via paralysis, or a block in stimulation, of the respiratory muscles
B.  epileptic convulsions caused by disorganized electrical activity in the brain
C.  by a heart attack
D.  suffocation via tetanus, or constant stimulation, of the respiratory muscles
E.  paralysis of skeletal muscles

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

Gather Content
· What do you know about the effect of inhibition of acetylcholinesterase? What other information is related to the question?

Choose Answer
· Given what you now know, what information is most likely to produce the correct answer?

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

D.  suffocation via tetanus, or constant stimulation, of the respiratory muscles

Clarify Question
· What is the key concept addressed by the question?
        o The question asks about the effect of inhibition of acetylcholinesterase.
· What type of thinking is required?
        o You are being asked to analyze statements about the effect of inhibition of acetylcholinesterase to predict how sarin gas would kill a person.

Gather Content
· What do you know about the effect of inhibition of acetylcholinesterase? What other information is related to the question?
        o The motor neuron releases the neurotransmitter acetylcholine into the neuromuscular junction. Acetylcholine binds to receptors in the muscle cell membrane to open Na+ channels. The influx of Na+ ions depolarizes the muscle cell membrane causing the muscle to contract. For the muscle to relax, the enzyme acetylcholinesterase breaks down the acetylcholine, allowing the muscle cell to repolarize. If a signal cannot reach a muscle and cause contraction, this is called paralysis. If a muscle remains contracted and cannot relax this is called tetanus.

Choose Answer
· Given what you now know, what information is most likely to produce the correct answer?
        o Sarin gas inhibits acetylcholinesterase, which means that acetylcholine cannot be broken down. After a nerve stimulates a muscle, the muscle will contract and will not be able to relax again. This is a state called tetanus. If this happens in the respiratory muscles after inhaling sarin gas then the patient will no longer be able to breathe and will suffocate.

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 This question asked you to analyze statements about the effect of inhibition of acetylcholinesterase to predict how sarin gas would kill a person. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you think that the muscle cells would not be able to contract if exposed to sarin gas, causing paralysis? Did you think that sarin gas would affect the nervous system instead of muscle contractions?