bio question neurotransmitter

[pizza1994]

patients injected with agents that paralyze muscles during surgeries must be artifically ventilated until they recover. These drugs interfere with which neurotransmitter?

a) Acetylcholine

b) Norepinephrine

c) dopamine

d) GABA

why is the answer A?

I thought it was B! isnt ventilation controlled by Norepinephrine?

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[sillyjoe]

patients injected with agents that paralyze muscles during surgeries must be artifically ventilated until they recover. These drugs interfere with which neurotransmitter?

a) Acetylcholine

b) Norepinephrine

c) dopamine

d) GABA

why is the answer A?

I thought it was B! isnt ventilation controlled by Norepinephrine?

No, neurons that innervate muscle release acetylcholine at the neuromuscular junction as the primary stimulus for the signal transduction that eventually leads to contraction.

For the MCAT, norepinephrine is used as a neurotransmitter in the post-ganglionic neuronal sympathetic response and small amounts of it are also released from the adrenal medulla directly into circulation. It is easier to remember the latter fact by recognized that the chromaffin cells in the adrenal medulla are just modified sympathetic post-ganglionic fibers and therefore release norepinephrinee and epinephrine.

 

[pizza1994]

No, neurons that innervate muscle release acetylcholine at the neuromuscular junction as the primary stimulus for the signal transduction that eventually leads to contraction.

For the MCAT, norepinephrine is used as a neurotransmitter in the post-ganglionic neuronal sympathetic response and small amounts of it are also released from the adrenal medulla directly into circulation. It is easier to remember the latter fact by recognized that the chromaffin cells in the adrenal medulla are just modified sympathetic post-ganglionic fibers and therefore release norepinephrinee and epinephrine.

yeah so when you increase breathing rate due to the sympathetic response then will there be a release of norepinephrine?

 

[dnrs]

Diaphragm is skeletal muscle and is under the control of the somatic nervous system which uses acetylcholine as its neurotransmitter.

 

[Czarcasm]

Yep, and just to add to onto what dnrs said, (if you haven't already realized) acetylcholine is an excitatory neurotransmitter for skeletal muscle, which facilitates skeletal muscle contraction. Blocking Ach from binding to it's receptor will prevent skeletal tissue from depolarizing, ultimately preventing the action potential needed for (diaphragm) contraction to occur.

 

[sillyjoe]

yeah so when you increase breathing rate due to the sympathetic response then will there be a release of norepinephrine?

You bring up a very interesting point. The fact that there is both voluntary and involuntary control of breathing. You breath all the time when and you are not thinking about it but if you wanted to you could hyperventilate right now. Or if you have increased CO2 in your blood you will start to involuntarily hyperventilate.

The important thing to know for this question in my opinion was addressed by @dnrs which is that the diaphragm is a striated skeletal muscle under somatic control and therefore uses acetylcholine to contract the muscle. So it is blocking acetylcholine. Even without the ventilation part of the question you could already hone in on acetylcholine since it is the major neurotransmitter in skeletal muscle. The question even focuses your attention to breathing being paralyzed so you know they are referring to the somatic system since you know the diaphragm is skeletal muscle.

Finally, try not to get tripped up on a future question thinking that acetylcholine being the only way to block muscle contraction. There are multiple mechanisms. Another popular one is to block the sodium channels in muscle to prevent depolarization.

 

[Cawolf]

This is a drug I am very familiar with, having used it many times.

If you are interested @pizza1994, look up succinylcholine.

It functions by acting as a nicotinic acetylcholine receptor agonist - so clearly A is correct

 

[sillyjoe]

This is a drug I am very familiar with, having used it many times.

If you are interested @pizza1994, look up succinylcholine.

It functions by acting as a nicotinic acetylcholine receptor agonist - so clearly A is correct

Interesting. I learned in pharm that intubation is one of the few times you want to use a depolarizing block.

 

[Cawolf]

Yes, that's what I carried it for.

The agency I work for now stocks Rocuronium as the preferred paralytic for facilitated intubation.

 

[pizza1994]

You bring up a very interesting point. The fact that there is both voluntary and involuntary control of breathing. You breath all the time when and you are not thinking about it but if you wanted to you could hyperventilate right now. Or if you have increased CO2 in your blood you will start to involuntarily hyperventilate.

The important thing to know for this question in my opinion was addressed by @dnrs which is that the diaphragm is a striated skeletal muscle under somatic control and therefore uses acetylcholine to contract the muscle. So it is blocking acetylcholine. Even without the ventilation part of the question you could already hone in on acetylcholine since it is the major neurotransmitter in skeletal muscle. The question even focuses your attention to breathing being paralyzed so you know they are referring to the somatic system since you know the diaphragm is skeletal muscle.

Finally, try not to get tripped up on a future question thinking that acetylcholine being the only way to block muscle contraction. There are multiple mechanisms. Another popular one is to block the sodium channels in muscle to prevent depolarization.

perfect thanks!