Flashcards in Autonomic nervous system Deck (18)
alpha 1 receptor effects
Most vascular smooth muscle contraction, increased force on heart, prostate contraction, pupillary dilator muscle contraction (pupil dilation)
alpha 2 receptor effects
Postsynaptic CNS (decrease SNS tone), presynaptic ANS (decreased NT release), some vascular smooth muscle contraction
beta 1 receptor effects
heart (increased force and rate), Juxtaglomerular cells (increase renin release)
beta 2 receptor effects
relaxation of Skeletal muscle blood vessels, relaxation of Bronchial smooth muscle, uterus relaxation
beta 3 receptor effects
Increased lipolysis in fat cells
epinephrine activates which receptors
all (alpha1&2, beta 1,2&3) (the fight or flight hormone)
Cardiac - Positive inotropic and chronotropic effect.
Vascular: Vasoconstriction (splanchnic) and vasodilation (skeletal muscle)
Smooth muscle - Relaxation of GI, uterine and bronchial.
Metabolic - Elevates serum glucose and free fatty acids.
epinephrine clinical use
Promote local hemostasis and to decrease systemic absorption of local anesthetics
ALL catecholamines are extensively metabolized in gut and liver following PO administration (first pass phenomenon) due to abundance of COMT. Epi not administered orally; Excretion - Rapidly inactivated in body by COMT or MAO. Metabolites excreted in urine. Duration of action 1-4 hr.
epinephrine adverse effects
angina, anxiety/fear, cardiac arrhythmias, dyspnea, headache, hypertension, peripheral vasoconstriction, tissue necrosis, tremor
norepinephrine activates which receptors?
all but beta 2
Similar to epinephrine, except do not see relaxation of smooth muscle from β2 activation (i.e. bronchial smooth muscle). No relaxation of skeletal smooth muscle vasculature- therefore, increases in blood pressure are more exaggerated.
Norepinephrine: Clinical Use
Duration of action of norepinephrine
shorter than epinephrine
norepinephrine adverse effects
Similar to epinephrine, except hypertension is more pronounced due to α1 stimulation without β2 balance.
Dopamine Receptor Activation and Effects (outside CNS)
D1: Vasodilation. Especially prominent in renal vasculature.
D2: Presynaptic receptors. Negative feedback to inhibit further norepinephrine, and possibly dopamine release.
β1: Positive inotropic and chronotropic effect
α1: Seen only at high doses. Causes vasoconstriction.