Emergency Medications, Pharmacology

What does Adrenergic and Cholinergic mean?

When it comes to terms like Cholinergic, Anticholinergic, Adrenergic, etc. I find myself in a sea of double negatives and symptoms swirling about so much so that I lose my footing. It’s complicated, but not SO complicated that it can’t be simplified, at least a little bit.

Adrenergic stimulates Sympathetic AKA fight or flight

Cholinergic stimulates Parasympathetic AKA rest and digest

Sympathetic and Parasympathetic nervous systems (AKA the two divisions of the Autonomic Nervous System) hit up 2 receptors: Alpha and Beta. From there the Alpha and Beta receptors are subcategorized. For simplification’s sake, I am going to only talk about Alpha receptors as one category (even though there are 2 alpha receptors) and Beta-1 and Beta-2 (even though there are 3 beta receptors).


What does an Alpha Receptor do?

  • Vessel smooth muscle control
    • Contraction- increases BP
    • Relaxation- decreases BP
  • Production/Storage of glucose from the liver
    • Glycogenesis- “store it up for later”
    • Glycogenolysis- “break it down for use now”
  • Sweat gland control
    • Diaphoresis-Shweatty
    • Dry skin-Not schweatty

What does a Beta-1 Receptor do?

  • Heart rate control
  • Heart contractility- The force of a heartbeat
  • Heart automaticity- The speed electricity is moving through the heart

What does a Beta-2 Receptor do?

  • Respiration rate control
  • Smooth muscle control of the bronchi/bronchioles
    • Bronchodilation
    • Bronchoconstriction

These receptors do other things but remember to simplify!!!

Another way to think about these receptors is to compare them to faucets, they put out water, and depending on which knob you turn (hot or cold) will determine the temperature of water.

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When the “adrenergic” knob is turned, what temperature of water are you going to get?

  • Alpha
    • Vasoconstriction- Increase BP
    • Glycogenolysis- “break it down for use now”
    • Diaphoresis- Sweaty sweat sweet.
  • Beta-1
    • Increase HR
    • Increase Contractility
    • Increase Automaticity
  • Beta-2
    • Increase Respirations
    • Bronchodilation

Now the “cholinergic” knob is turned, what temp water now?

  • Alpha
    • Vasodilation- Decrease BP
    • Glycogenesis- “store it for later”
    • Dry skin
  • Beta-1
    • Decrease HR
    • Decrease Contractility
    • Decrease Automaticity
  • Beta-2
    • Decrease Respirations
    • Bronchoconstriction

Check out this chart I made for you:

Adrenergic Cholinergic


So if you give Succinylcholine, you will be resting, and by resting I mean momentary paralysis. If you give Epinephrine you will be fighting and flighting, and freaking a smidge.

Before I leave this post, I would like to throw a few bread crumbs for you to chew on.

When I think of Cholinergic, I think of Chill with Cheetos. Thus, if you have an anticholinergic, it is an anti Chill and Cheetos (AKA a Jerk). Giving a patient atropine, an anticholinergic, will jump up and slap that Cheeto straight outta ya mouth then makes you go for a run.

For Adrenergic I think of adrENERGY. The kind of fool that gets the lunk alarm at planet fitness. Conversely, if I give a patient an adrenergic antagonist I summoning a hippy that is passing them a joint… puff, puff, pass my friend and chill.

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