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Please help! Cholinergic v Adrengergic

Student Assist   (19,160 Views | 4 Replies)

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I have a quick question for you, can you please explain cholinergic and adrenergic? Im confused as two what subcategories follow? From what I took during lecture, the PNS has ACh, NE, and EP neurotransmitters. Followed by the receptors: Alpha 1 and 2, Beta 1 and 2, and dop (sometimes). And for SNS, there are no transmitters but the receptors are: Alpha 1 and 2, beta 1 and 2 and dop. Am I understanding that correctly?

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malenurse69 specializes in ICU.

223 Posts; 3,725 Profile Views

I think you have a few things mixed up. See if you can follow.

You have periphreal and central nervous system

PNS = periphreal nervous system

Within your PNS falls parasympathetic nervous system and sympathetic nervous system.

Parasympathetic = cholenergic = rest and digest

Sympathetic = adrenergic = fight or flight

Sympathetic works off Norepinephrine, epinephrine and dopamine.

Parasympathetic works off Acetylcholine

These are called neurotransmitters.

Sympathetic has 4 types of receptors you need to know, beta 1, 2 Alpha 1, 2

Parasympathetic has nicotinic and muscarinic receptors

Think everything with adrenergic = sympathetic and cholenergic = parasympathetic and itll all make more sense.

Your parasympathetic and sympathetic nervous systems are at equilibrium, and if one is suppressed the other system will have more dominance. So if you suppress your parasympathetic (cholinergic) nervous system what would you expect? Increased influence from your sympathetic nervous system, which is adrenergic, which means fight or flight, which means what? Increased heart rate etc.

Sympathomimetics simply means mimicking a sympathic response

Sympatholytic means the opposite

Anticholinergic would do what then? An adrenergic = sympathetic response.

Cholinesterase (ends with ase = enzyme) breaks down your acetylcholine neurotransmitters, so it reduces cholinergic response. Cholinesterase inhibitor would do what then? Promote cholinergic response.

This is the way you have to think, its a very binary way of thinking, you just have to understand adrenergic and cholinergic does, and youll know instantly if something is a adrenergic blocker boom your promoting a parasympathetic response.

I went over the very basics and I'm not going to flesh out what receptors do what, I just gave you the frameworks and its your job to fill in the dirty details

Edited by malenurse69

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612 Posts; 15,188 Profile Views

Cholinergic divides into:

1) Nicotinic

2) Muscurinic

Nicotinic is found mainly on skeletal muscle, and is excitatory.

Muscurinic is mainly found on cardiac muscle, it is both excitatory and inhibitory.

An anticholinergic such as Atropine Sulfate will effect the Muscurinic receptors of the heart. Atropine will increase the HR.

Adrenergic has a couple different receptors but let's stick to:

Alpha 1

Alpha 2

Beta 1

Beta 2.

Activation of the receptors:

Activating Alpha 1 will cause vasoconstriction that's the biggest thing to remember. Why? Because Levophed (norepi) used in the ICU is used to vasoconstrict in septic shock. Watch those fingers though ... they'll be cool and eventually blue/black!

Beta 1 is mainly on the HEART. Epinephrine targeting here will cause a positive chronotropic effect (Heart rate) and a positive inotropic (force of contraction). Selective beta blockers are used frequently to reduce the HR and mildly reduce the BP. Beta blockers are used a lot for pts with afib to control RVR.

Alpha 2 the biggest thing here and relatable to nursing is CLONIDINE. CLONIDINE is agonistic to alpha 2 and will reduce the BP.

Beta 2 is the LUNGS. Targeting this one will cause bronchodilation.

Such as???? Short Acting Beta Agonists such as???? Albuterol.

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Esme12 has 40 years experience as a ASN, BSN, RN and specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

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Basically the Parasympathetic Nervous System (PNS = Cholingeric; uses Acetylcholine (ACh) as a neurotransmitter), and Sympathetic Nervous System (SNS = Adrenergic; uses Nor-epinephrine (NE) as a neurotransmitter, or epinephrine (aka adrenaline, hence the name adrenergic)). The two systems directly oppose one another and are collectively called the Autonomic Nervous System (ANS), The Central Nervous System (CNS), is the main boss here, it controls everything, and ANS is just a part of it.

Generally, PNS performs the 'rest and digest' sort of actions, it's predominant when you are sleeping, digesting food, or just relaxing. While SNS is the 'fight or flight' system, and is reved up during emergencies or any sort of state of excitement.

Cholinergic vs. adrenergic fibers

Cholinergic fibers use acetylcholine (ACh)

Adrenergic fibers use norepinephrine (NE)

The effect of ACh or NE – excitatory or inhibitory – will depend on the receptors.

Cholinergic Receptors : are named according to drugs that bind to them, mimicking the effects of ACh.

Nicotinic receptors are found in the somatic system on the motor end plates of skeletal muscle cells and in the ANS on all postganglionic neurons and the hormone producing cells of the adrenal medulla. ACh binding to a nicotinic receptor is excitatory.

Muscarinic receptors (named for muscarine, a mushroom poison) are found in effectors that are stimuled by cholinergic fibers. The effect is inhibitory or excitatory based on the target

Adrenergic Receptors : are found on the organs that are stimulated by sympathetic fibers (using NE). There are two types :

Alpha : excitatory

Beta : inhibitory, except in the cardiac muscle where it is excitatory. Both types are found in many organs

Knowledge of where adrenergic and cholinergic receptors are found can help in drug development

Atropine : an anticholinergic drug that blocks parasympathetic effects, it is used to suppress salivation and respiratory secretions; also used to dilate the pupil

Neostigmine : inhibits cholinesterase; used to treat skeletal muscle impairment due to lack of ACh

Tricyclic antidepressants : prolong the activity of NE, which is a "feel good" neurotransmitter

Over-the-counter treatments: for colds, coughs, allergies and nasal congestion stimulate alpha adrenergic receptors

Beta blockers : work on the beta-one receptors of the heart to reduce heart rate and prevent arrhythmia

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MSNce1 has 34 years experience and specializes in med-surg, mother-baby, teaching, peds.

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Very helpful response to others and well delivered:)

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