Autonomic Nervous System Receptors & Actions

❤ Heart

Q: What is the sympathetic effect of β1 receptor activation on myocardial tissue?
A: ↑ Contractility

Q: What parasympathetic receptor decreases contractility of the heart?
A: M2

Q: Which receptor increases SA node firing rate (HR) under sympathetic stimulation?
A: β1

Q: Which parasympathetic receptor decreases SA node activity (↓HR)?
A: M2

Q: What is the effect of β1 stimulation on AV node and His-Purkinje system?
A: ↑ Automaticity & conduction velocity (CV)

Q: Which receptor decreases AV node conduction and may cause AV block?
A: M2

🩸 Vessels

Q: Which receptors mediate arterial constriction?
A: α1 > α2

Q: Which receptors cause venous constriction?
A: α2 > α1

Q: What is the effect of dopamine (DA) receptors in renal and mesenteric beds?
A: Vasodilation

Q: Which receptor dilates skeletal muscle and coronary vessels?
A: β2

🌬 Bronchial Tree

Q: Which receptor relaxes the bronchial smooth muscle?
A: β2 (sympathetic)

Q: Which receptor constricts the bronchial tree?
A: M3 (parasympathetic)

🧠 Kidney

Q: Which receptor increases renin release?
A: β1

Q: Which receptor promotes diuresis (via ADH inhibition)?
A: α2

👁 Eye

Q: Which receptor contracts radial muscle (mydriasis)?
A: α1

Q: Which receptor contracts sphincter muscle (miosis)?
A: M2, M3

Q: Which receptor relaxes ciliary muscle for far vision?
A: β2

Q: Which receptor contracts ciliary muscle for near vision?
A: M2, M3

🍽 GI Tract

Q: Which receptor decreases salivary secretion?
A: α2

Q: Which receptor increases salivary secretion?
A: M3

Q: Which receptors decrease GI motility & tone?
A: α1, α2, β1, β2

Q: Which receptors increase GI motility & tone?
A: M2, M3

Q: Which receptor contracts GI sphincters?
A: α1

Q: Which receptor relaxes GI sphincters?
A: M2, M3

Q: Which receptor relaxes gallbladder & ducts?
A: β2

Q: Which receptor contracts gallbladder & ducts?
A: M

🥛 Pancreas & Metabolism

Q: Which receptor increases glucagon secretion (α cells)?
A: α1

Q: Which receptor decreases insulin secretion (β cells)?
A: α2

Q: Which receptor increases insulin secretion?
A: β2

Q: Which receptors mediate lipolysis in adipocytes?
A: α1, β1, β2, β3

Q: Which receptor mediates glycogenolysis & gluconeogenesis in the liver?
A: β2

🩸 Hematologic

Q: Which receptor causes RBC release from the spleen?
A: α1

Q: Which receptor increases thrombocyte aggregation?
A: α2

👶 Uterus

Q: Which receptor causes uterine contraction?
A: α1

Q: Which receptor causes uterine relaxation?
A: β2

🚽 Bladder

Q: Which receptor relaxes the detrusor muscle?
A: β2

Q: Which receptor contracts the detrusor muscle?
A: M2, M3

Q: Which receptor contracts the trigone & sphincter?
A: α1

Q: Which receptor relaxes the trigone & sphincter?
A: M2, M3

💦 Sweat Glands

Q: Which sympathetic receptor increases sweat secretion?
A: α1

Q: Which parasympathetic receptor increases sweat secretion?
A: M

⚡ Sodium-Potassium Pump

Q: Which receptor stimulates the Na⁺/K⁺ pump, lowering plasma K⁺?
A: β2