Sympathetic and parasympathetic effects and adrenergic and cholinergic receptor physiology tested on USMLE Step 1.
36 cards · basic cards · AI-written, checked twice. Edit anything.
- What neurotransmitter is released by all preganglionic autonomic neurons (both sympathetic and parasympathetic)?
- Acetylcholine
- What receptor type do preganglionic autonomic fibers act on at the ganglion?
- Nicotinic acetylcholine receptors
- What neurotransmitter is released by most postganglionic sympathetic neurons onto target organs?
- Norepinephrine
- What neurotransmitter is released by postganglionic parasympathetic neurons onto target organs?
- Acetylcholine
- What is a notable exception among postganglionic sympathetic fibers that releases acetylcholine instead of norepinephrine?
- Sympathetic fibers innervating sweat glands
- What receptor type do postganglionic sympathetic fibers act on at sweat glands?
- Muscarinic acetylcholine receptors
- What is released directly into the bloodstream by the adrenal medulla in response to sympathetic stimulation?
- Epinephrine (and some norepinephrine)
- Why is the adrenal medulla considered a modified sympathetic ganglion?
- It is directly innervated by preganglionic sympathetic fibers releasing acetylcholine onto nicotinic receptors, without a postganglionic neuron in between
- What is the primary physiologic effect of alpha-1 adrenergic receptor activation on vascular smooth muscle?
- Vasoconstriction
- What second messenger system does the alpha-1 receptor signal through?
- Gq, activating phospholipase C to increase IP3 and diacylglycerol and raise intracellular calcium
- What is the primary physiologic effect of alpha-2 adrenergic receptor activation at presynaptic sympathetic nerve terminals?
- Inhibition of further norepinephrine release, providing negative feedback
- What second messenger system does the alpha-2 receptor signal through?
- Gi, inhibiting adenylate cyclase and decreasing cAMP
- What is the primary physiologic effect of beta-1 adrenergic receptor activation in the heart?
- Increased heart rate and contractility
- What second messenger system does the beta-1 receptor signal through?
- Gs, activating adenylate cyclase and increasing cAMP
- What is the primary physiologic effect of beta-2 adrenergic receptor activation on bronchial and vascular smooth muscle?
- Bronchodilation and vasodilation (relaxation of smooth muscle)
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