autonomic

autonomic

1. parasympathetic

   • preganglionic
     • cholinergic neurons
       • nicotinic receptors
   • postganglionic
     • cholinergic neurons
       • varicosities
         • synthesize Ach
           • small clear vesicles
         • can synthesize NO
     • muscarinic receptors
       • decrease SA node, heart rate, AV nodal conduction, contractility (atria only), releases EDRF from endothelium, constricts bronchioles, contracts GI walls, relaxes sphincters, increases saliva, gastric acid and pancreatic secretion, contracts detrusor muscle, erection, miosis, contracts ciliary muscle (near vision), lacrimal gland secretion

2. sympathetic

   • preganglionic
     • cholinergic neurons
       • nicotinic receptors
         • open sodium and potassium channels to depolarize
           • antagonized by curare
           • antagonized by hexamethonium in ganglia
     • to adrenal medulla
       • chromaffin cells
         • secrete catecholamines
           • overactive with pheochromocytoma
           • more potent to beta than alpha
   • postganglionic
     • cholinergic
       • muscarinic receptors
         • IP3, increase intracellular calcium, or decrease adenylyl cyclase and cAMP
       • only thermoregulatory sweat glands
     • adrenergic neurons
       • adrenoreceptors
         • alpha 1
           • constricts skin and skeletal muscle, contracts sphincters, mydriasis,
             • IP3, increase intracellular calcium
         • alpha 2
           • relaxes GI walls
             • inhibition of adenylyl cyclase, decrease cAMP
           • autoreceptor
             • negative feedback to conserve norepinephrine
           • heteroreceptor
             • inhibits GI function when activated by norepinephrine
         • beta 1
           • increase SA node, heart rate, AV nodal conduction and contractility; increase saliva excretion, lipolysis and renin secretion
             • stimulation of adenylyl cyclase, increase cAMP
         • beta 2
           • dilates skeletal muscle and bronchioles, relaxes GI walls and detrusor muscle, gluconeogenesis and glycogenolysis
             • stimulation of adenylyl cyclase, increase cAMP
         • both alpha
           • ejaculation, sweat, contracts pilomotor muscle (goose bumps), gluconeogenesis, glycogenolysis
         • both beta
           • dilates ciliary muscle (far vision)
       • varicosities
         • norepinephrine
           • small dense-core vesicles with ATP
         • neuropeptide Y
           • large dense-core vesicles
   • fight or flight