Pharmacology help Please

[djnme2000]

I'm in my second semester of nursing school and am trying to understand the pharmacology of it all. I've been reading the books but it all still seems like foreign to me. Can some one in "understandable" term explain to me the classes of drugs and about sympathetic and parasympathetic.....

I do understand that the sympathetic system is the fight or flight one and the other is the digest and rest one. But getting that to click with my brain and how it relates to drugs is literally mind boggling me LOL.

thanks in advance for any help.

Sabrina

[Tanya Q]

Here's my basic overview:

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Nervous system has 2 parts:

1. Somatic: controls skeletal muscle

2. Autonomic: controls smooth and cardiac muscle

Autonomic nervous system is further divided into 2 parts:

1. Sympathetic: capable of generalized response

2. Parasympathetic: capable of specific, localized response

Autonomic nervous system has preganglionic neurons (start in CNS)

that synapse with postganglionic neurons (go to effector organ)

1. Sympathetic

Preganglionic motor neuron à(ACh binds to Nicotinic Ach receptor) à

postganglionic neuron à (noradrenaline binds to adrenergic receptor)

à target organ

2. Parasympathetic

Preganglionic motor neuron à(ACh binds to Nicotinic Ach receptor) à

postganglionic neuron à (ACh binds to Muscarinic ACh receptor) à

target organ

The bolded areas are where sympathetic differs from parasympathetic,

which should help you deduce the affect a drug will have based on the

neurotransmitter or receptor it interacts with. There's a lot of details

missing! But it's a start.

[Tanya Q]

Since I have a few minutes, I thought I would add onto what I posted. Keeping the neurotransmitter/receptor differences between the sympathetic and parasympathetic nervous systems in mind, you can understand how various drugs target SNS or PNS:

Sympathetic

1. Adrenergic agonist (stimulates SNS)

2. Adrenergic antagonist (impedes SNS)

3. Noradrenaline reuptake inhibitor(stimulates SNS)

Parasympathetic

1. Muscarinic agonist (stimulates PNS)

2. Muscarinic antagonist (impedes PNS)

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Both

1. Nicotinic agonist (stimulates)

2. Nicotinic antagonist (impedes)

3. AChE inhibitor (stimulates)