Neurotransmitters of the nervous system

[reising1]

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I'm looking for someone to very simply state a general rule for neurotransmitters. For example, I know that somatic only uses Acetycholine. But what is a good general rule for sympathetic and parasympathetic nervous systems. I initially thought that epinephrine is for sympathetic and norepinephrine is for parasympathetic, but I am finding out this is wrong. So, can someone fill this in:

Somatic Nervous System - Acetycholine
Autonomic - Sympathetic Nervous System - ?
Autonomic - Parasympathetic Nervous System - ?

 

[eradicator]

I'm looking for someone to very simply state a general rule for neurotransmitters. For example, I know that somatic only uses Acetycholine. But what is a good general rule for sympathetic and parasympathetic nervous systems. I initially thought that epinephrine is for sympathetic and norepinephrine is for parasympathetic, but I am finding out this is wrong. So, can someone fill this in:

Somatic Nervous System - Acetycholine
Autonomic - Sympathetic Nervous System - ?
Autonomic - Parasympathetic Nervous System - ?

Sympathetic = "fight/flight" response, so it uses two. First it uses acetylcholine and then it uses epinephrine/norepinephrine (these two are both adrenaline hormones/neurotransmitters released released at end of sympathetic nerve fibers)

Parassympathtic = carries out basal activities and only uses acetylcholine

 

[reising1]

So everything uses ACh? I just want to triple check that. Is that true?

 

[reising1]

Sympathetic = "fight/flight" response, so it uses two. First it uses acetylcholine and then it uses epinephrine/norepinephrine (these two are both adrenaline hormones/neurotransmitters released released at end of sympathetic nerve fibers)

Parassympathtic = carries out basal activities and only uses acetylcholine

Here's a question from Examkrackers 1001 Bio Page 75

Which of the following statements regarding the autonomic nervous system is true?
A. ACh causes sympathetic stimulation and muscular vasoconstriction
B. ACh causes parasympathetic stimulation and muscular vasodilation
C. NE causes parasympathetic stimulation and muscular vasoconstriction
D. NE causes sympathetic stimulation and muscular vasodilation

The answer is D. But you said that sympathetic also uses ACh, so why isn't the answer A?

 

[eradicator]

Hey, sorry what i meant is:

the sympathetic NS uses acetylcholine first to stimulate release of epinephrine/norepi. ultimately it's using epinephrine to carry out it's designated function!!

 

[reising1]

Okay, thanks!

 

[Patassa]

Here's the way TBR lays it out.

Autonomic

1. Preganglionic fibers in both PS and S release acetycholine

2. Post ganglionic fibers in PS release acetylcholine, but the ones in S releases norepinephrine.


The confusing part is that EP and norEP can be released by nerve fibers AND the endocrine gland adrenal medulla. So the clear line between neurotransmitter and hormone is being breached here.

 

[reising1]

Okay, that follows what was previously said (by Eradicator). Thanks for the follow up!

 

[reising1]

2. Post ganglionic fibers in PS release acetylcholine, but the ones in S releases norepinephrine.

One clarification point here: for postganglionic, does S also release epinephrine? If not, then where does epinephrine come into play?

 

[eradicator]

One clarification point here: for postganglionic, does S also release epinephrine? If not, then where does epinephrine come into play?

Yes it does. I just group epi and norepi together cuz the are pretty similar

 

[Patassa]

One clarification point here: for postganglionic, does S also release epinephrine? If not, then where does epinephrine come into play?

It appears as though epinephrine does not come into play until the adrenal medulla is stimulated by the release of acetylcholine on it by the S preganglionic fiber.

Going off of my physiology book here, they are really similar compounds though and if we have to split I hair like this on the MCAT I'd be surprised.

 

[Patassa]

This might prove helpful.

 

[ashtray81]

Autonomic:
Must have 2 or more neurons that meet at a ganglion
Pre-ganglionic: Ach
Post-ganglionic: parasymptathetic (Ach)
sympathetic (Norepi)
ADRENAL sympatethic (Epinephrine)

PM me, and i'll send a link that will better explain it.

 

[reising1]

Okay, thank you to both of you! Very helpful.