Home > Uncategorized > Introduction to Human Anatomy Lecture 24 Notes

Introduction to Human Anatomy Lecture 24 Notes


Part 3 of our series on autonomic drugs.


Alpha and Beta Adrenergic Agonists and Blockers

ACh receptors on the visceral organs are different from those on muscle.

muscerinic – heart

nicotinic – skeletal muscle

Alpha adrenergic receptor sites.  Alpha 1 and 2.

Beta adrenergic receptor sites.  Beta 1, 2 and 3.

If you give a man epinephrine, if we could block the beta one sites, or beta two sites, we could hit certain organs.

Relative Activity of Certain Adrenergic Amines on peripheral Thetic receptors

Drug                     Potency Ration (ephedrine)        Receptor Ratio (alpha/beta)

Pheylephrine           0.05                 95/5

Novaphapherin             0.7                    91/10

Levo                             0.2                       75/25

Epinepherine                   1                          50/50

Edyn                0.1                         25/75

Iso                    0.9                 5/95

Parasympathetic (rest and digest) or sympathetic (fight or flight).  Atropine is a typical blocker of the parasympathetic system.  Sympathetic into alpha and beta.  Alpha on the eyes and most blood vessels, causes vasoconstriction.  Beta receptors are everywhere else, blood vessels to the heart and skeletal muscle, vasodialator

Beta into beta 1 and 2.  Beta one in the heart, tachycardia.  Beta two in the airways, bronchodialation.  Sympathetic system,  EPI ephedrine amphedamine.

Alpha Adrenergic Agonists

Prototype: phenylephrine

PK: activate alpha adrenergic receptor sites.

Clinical Uses: vasoconstricter, increase BP of acute hypotension.  Increase TPR.  Postural orthostatic hypotension is gravity pulling blood from the brain when you try to get up.

Adverse Effects: reflex bradycardia

Beta Adrenergic Agonists

Prototype: isoproternol

PD : Activate beta adrenergic receptors

Clinical Uses:

Beta 1 Adrenergic Agonists


Cardiac stimulant

Beta 2 Adrenergic Agonists



Other Beta Two Adrenergic Agonists


Non catechoamines are orally active; ephedrine, amphetamine.  EPI must be inhaled or injected.

In order of increasing nervous system stimulation: EPI, ephedrine, amphetamine


Lightning: cloud to cloud, cloud to ground, intracloud

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