Exam 2 SG Overview

Ahangari Exam 2 SG points (all info from class + ppt notes -> generated review by copilot)

Autonomic Nervous System (ANS)

Controls visceral organs, glands, blood vessels; composed of sympathetic and parasympathetic divisions.

Sympathetic Origin

Thoracolumbar outflow: T1–L2/3 lateral horn.

Parasympathetic Origin

Craniosacral outflow: CN III, VII, IX, X and S2–S4.

Preganglionic Neurotransmitter (ANS)

Acetylcholine (ACh) for both sympathetic and parasympathetic.

Postganglionic Neurotransmitter (Sympathetic)

Norepinephrine (NE).

Postganglionic Neurotransmitter (Parasympathetic)

Acetylcholine (ACh).

Function of Sympathetic System

Emergency response: ↑HR, ↑BP, pupil dilation, bronchodilation, sphincter contraction, ↓GI motility.

Function of Parasympathetic System

Rest/digest: ↓HR, pupil constriction, ↑GI motility, ↑gland secretion, bladder contraction.

Adrenergic Receptors

Receptors for NE/Epi: α1, α2, β1, β2.

α1 Receptor Location

Vascular smooth muscle (skin, splanchnic), GI/bladder sphincters, radial iris muscle.

α1 Receptor Function

Contraction: vasoconstriction, pupil dilation.

α1 Receptor Mechanism

Gq → ↑IP3 → ↑Ca²⁺ → contraction.

Clinical: Excess NE on α1

Hypertension, excess sweating.

α2 Receptor Location

Presynaptic terminals, platelets, fat cells, GI walls.

α2 Receptor Function

Inhibition: relaxation, ↓NE release.

α2 Receptor Mechanism

Gi → ↓adenylate cyclase → ↓cAMP.

β1 Receptor Location

SA node, AV node, ventricular myocardium.

β1 Receptor Function

↑HR, ↑conduction velocity, ↑contractility.

β1 Receptor Mechanism

Gs → ↑adenylate cyclase → ↑cAMP.

Clinical: Propranolol

β1 blocker → ↓HR and ↓contractility.

β2 Receptor Location

Bronchial smooth muscle, skeletal muscle vasculature, GI/bladder walls.

β2 Receptor Function

Relaxation: bronchodilation, vasodilation.

β2 Receptor Mechanism

Gs → ↑cAMP.

Clinical: Albuterol

β2 agonist → bronchodilation.

Cholinergic Receptors

Nicotinic and muscarinic receptors.

Nicotinic Receptor Location

Autonomic ganglia, adrenal medulla, neuromuscular junction.

Nicotinic Receptor Function

Excitation via Na⁺/K⁺ channel opening.

Muscarinic Receptor Location

Heart, smooth muscle, glands.

Muscarinic Heart Effect

Inhibitory: ↓HR, ↓AV conduction.

Muscarinic Smooth Muscle/Gland Effect

Excitatory: ↑GI motility, ↑secretion.

Muscarinic Mechanism (Heart)

Gi → open K⁺ channels → ↓phase 4 depolarization.

Muscarinic Mechanism (Smooth Muscle)

Gq → ↑IP3 → ↑Ca²⁺.

Muscarinic Blocker

Atropine.

Autonomic Centers: Medulla

Vasomotor, respiratory, swallowing, coughing, vomiting centers.

Autonomic Centers: Pons

Pneumotaxic respiratory center.

Autonomic Centers: Midbrain

Micturition center.

Autonomic Centers: Hypothalamus

Temperature regulation, endocrine, sleep, thirst, food intake, memory, emotional/sexual behavior.

ANS Effect on Eye (Sympathetic)

α2 dilation, β accommodation, ↓lacrimal secretion.

ANS Effect on Eye (Parasympathetic)

Pupil constriction, ciliary muscle contraction, ↑lacrimal secretion.

ANS Effect on Heart (Sympathetic)

β1: ↑HR, ↑conduction, ↑contractility.

ANS Effect on Heart (Parasympathetic)

↓HR, ↓conduction.

ANS Effect on Lungs (Sympathetic)

β2 bronchodilation, ↓secretion.

ANS Effect on Lungs (Parasympathetic)

Bronchoconstriction, ↑secretion.

ANS Effect on GI (Sympathetic)

β2 relaxation, α1 sphincter contraction, ↓secretion.

ANS Effect on GI (Parasympathetic)

↑peristalsis, sphincter relaxation, ↑secretion.

ANS Effect on Liver (Sympathetic)

β: gluconeogenesis.

ANS Effect on Liver (Parasympathetic)

Glycogenesis.

ANS Effect on Gallbladder (Sympathetic)

β2 relaxation.

ANS Effect on Gallbladder (Parasympathetic)

Contraction.

ANS Effect on Pancreas (Sympathetic)

α inhibits insulin; β activates insulin; α inhibits exocrine secretion.

ANS Effect on Pancreas (Parasympathetic)

Activates secretion.

ANS Effect on Adrenal Medulla

Sympathetic preganglionic ACh → secretion of Epi (80%) & NE (20%).