title: Table of neurotransmitter actions in the ANS
text: # Table of neurotransmitter actions in the ANS
  
  ## Circulatory system
  
  ### Heart
  
  | Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
  | - | - | - |
  | cardiac output | β1, (β2): increases | M2: decreases |
  | SA node: heart rate (chronotropic) | β1, (β2): increases | M2: decreases |
  | Atrial cardiac muscle: contractility (inotropic) | β1, (β2): increases | M2: decreases |
  | at AV node | β1: increases conduction increases cardiac muscle automaticity | M2: decreases conduction Atrioventricular block |
  | Ventricular cardiac muscle | β1, (β2): increases contractility (inotropic) increases cardiac muscle automaticity | --- |
  
  ### Blood vessels
  
  | Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
  | - | - | - |
  | vascular smooth muscle in general | α1: contracts; β2: relaxes | M3: relaxes |
  | renal artery | α1: constricts | --- |
  | larger coronary arteries | α1 and α2: constricts | --- |
  | smaller coronary arteries | β2: dilates | --- |
  | arteries to viscera | α: constricts | --- |
  | arteries to skin | α: constricts | --- |
  | arteries to brain | α1: constricts | --- |
  | arteries to erectile tissue | α1: constricts | M3: dilates |
  | arteries to salivary glands | α: constricts | M3: dilates |
  | hepatic artery | α: constricts | --- |
  | arteries to skeletal muscle | β2: dilates | --- |
  | Veins | α1 and α2: constricts β2: dilates | --- |
  
  ### Other
  
  | Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
  | - | - | - |
  | platelets | α2: aggregates | --- |
  | mast cells - histamine | β2: inhibits | --- |
  
  ## Respiratory system
  
  | Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
  | - | - | - |
  | smooth muscles of bronchioles* | β2: relaxes (major contribution) α1: contracts (minor contribution) | M3: contracts |
  
  $^✱$ The bronchioles have no sympathetic innervation, but are instead affected by circulating adrenaline
  
  ## Visual system
  
  | Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
  | - | - | - |
  | Pupil dilator muscle | α1: Dilates (causes mydriasis) | |
  | Iris sphincter muscle | - | M3: contracts (causes miosis) |
  | Ciliary muscle | β2: relaxes (causes long-range focus) | M3: contracts (causes short-range focus) |
  
  ## Digestive system
  
  | Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
  | - | - | - |
  | salivary glands: secretions | β: stimulates viscous, amylase secretions α1: stimulates potassium secretions | M3: stimulates watery secretions |
  | lacrimal glands (tears) | β: stimulates protein secretion | secretion of tears by stimulating muscarinic receptors (M3) |
  | juxtaglomerular apparatus of kidney | β1: renin secretion | --- |
  | parietal cells | --- | M1: Gastric acid secretion |
  | liver | α1, β2: glycogenolysis, gluconeogenesis | --- |
  | adipose cells | β1, β3: stimulates lipolysis | --- |
  | GI tract (smooth muscle) motility | α1, α2, β2: decreases | M3, (M1): increases |
  | sphincters of GI tract | α1, α2, β2: contracts | M3: relaxes |
  | glands of GI tract | no effect | M3: secretes |
  
  ## Endocrine system
  
  | Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
  | - | - | - |
  | pancreas (islets) | α2: decreases insulin secretion from beta cells, increases glucagon secretion from alpha cells | M3: increases secretion of both insulin and glucagon. |
  | adrenal medulla | N (nicotinic ACh receptor): secretes epinephrine and norepinephrine | --- |
  
  ## Urinary system
  
  | Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
  | - | - | - |
  | Detrusor urinae muscle of bladder wall | β2, β3: relaxes | M3: contracts |
  | internal urethral sphincter | α1: contracts | M3: relaxes |
  
  ## Reproductive system
  
  | Target | Sympathetic (adrenergic) | Parasympathetic (muscarinic) |
  | - | - | - |
  | uterus | α1: contracts (pregnant) β2: relaxes (non-pregnant) | --- |
  | genitalia | α1: contracts (ejaculation) | M3: erection |
  
  ## Integumentary system
  
  | Target | Sympathetic (muscarinic and adrenergic) | Parasympathetic |
  | - | - | - |
  | sweat gland secretions | α1: stimulates (minor contribution) | M: stimulates (major contribution) |
  | arrector pili | α1: stimulates | --- |
  