autonomic nervous system (ANS) - Further reading

That part of the nervous system which supplies the glands (eg the salivary and sweat glands), heart muscle, and smooth muscle (eg the walls of blood vessels and the bladder). It consists of groups of nerve cells outside the central nervous system, interposed between it and the target organs. The sympathetic (S) system is distributed throughout the whole body, particularly to the blood vessels. The parasympathetic (P) system is distributed to the gastro-intestinal, respiratory, and urogenital systems, and to the eye. Where S and P fibres supply the same structure, their effects are often opposite, to produce a balance with multiple gradations: for example, S nervous activity increases heart rate, P decreases it; S dilates the pupil, P constricts it. In general terms, the S system prepares the body for action, while the P is concerned with the conservation of energy.

The autonomic nervous system (ANS) (or visceral nervous system) is the part of the nervous system that controls homeostasis or the constancy of the « milieu intérieur » (the content of tissues in gasses, ions and nutrients). All these visceral sensory informations constantly and unconsciously modulate the activity of the motor neurons of the ANS

Motor neurons

Motor neurons of the ANS are also located in ganglia of the PNS, called “autonomic ganglia”.

	Sympathetic (adrenergic, with exceptions)	Parasympathetic (muscarinic)
circulatory system
cardiac output	increases	M2: decreases
SA node: heart rate (chronotropic)	β1, β2: increases	M2: decreases
cardiac muscle: contractility (inotropic)	β1, β2: increases	M2: decreases (atria only)
conduction at AV node	β1: increases	M2: decreases
vascular smooth muscle	M3: contracts; β2 = relaxes	---
platelets	α2: aggregates	---
mast cells - histamine	β2: inhibits	---
respiratory system
smooth muscles of bronchioles	β2: relaxes (major contribution); α1: contracts (minor contribution)	M3: contracts
nervous system
pupil of eye	α1: relaxes	M3: contracts
ciliary muscle	β2: relaxes	M3: contracts
digestive system
salivary glands: secretions	β: stimulates viscous, amylase secretions; α1 = stimulates potassium cation	stimulates watery secretions
lacrimal glands (tears)	decreases	M3: increases
kidney (renin)	secretes	---
parietal cells	---	M1: secretion
liver	α1, β2: glycogenolysis, gluconeogenesis	---
adipose cells	β3: stimulates lipolysis	---
GI tract motility	decreases	M1, M3: increases
smooth muscles of GI tract	α, β2: relaxes	M3: contracts
sphincters of GI tract	α1: contracts	M3: relaxes
glands of GI tract	inhibits	M3: secretes
endocrine system
pancreas (islets)	α2: decreases secretion	---
adrenal medulla	N: secretes epinephrine	---
urinary system
bladder wall	β2: relaxes	contracts
ureter	α1: contracts	relaxes
sphincter	α1: contracts; β2 relaxes	relaxes
reproductive system
uterus	α1: contracts; β2: relaxes	---
genitalia	α: contracts	M3: erection
integument
sweat gland secretions	M: stimulates (major contribution); α1: stimulates (minor contribution)	---
arrector pili	α1: stimulates	---

Further reading

The Second Brain, Michael D.