THE AUTONOMIC NERVOUS SYSTEM

Table 3 : Actions of the Autonomic Nervous System
Effector Organ	Autonomic Division	Type of Receptor	Action
Eye : pupil	sympathetic parasympathetic	alpha muscarinic	dilation of the pupil constriction of the pupil
Eye : ciliary muscle	sympathetic parasympathetic	beta muscarinic	allows far vision allows near vision
Lachrymal (tear) glands	sympathetic parasympathetic	beta muscarinic	vasoconstriction secretion of tears
Salivary glands	sympathetic parasympathetic	alpha muscarinic	vasoconstriction and secretion of mucous with a low enzyme count secretion of watery saliva with a high enzyme count
Heart	sympathetic parasympathetic	beta alpha muscarinic	dilation of coronary arteries, increased heart rate, increased force of contraction, increased rate of pacemaker conduction coronary artery constriction slows, heart rate, reduces contraction and conduction, constricts coronary arteries
Bronchii	sympathetic parasympathetic	beta muscarinic	dilation constriction and mucous secretion
Oesophagus	sympathetic parasympathetic	alpha muscarinic	vasoconstriction peristalsis, secretion of mucous
Stomach and Intestines	sympathetic parasympathetic	beta alpha muscarinic	inhibition of peristalsis and secretion vasoconstriction, spinctre contraction peristalsis and secretion
Spleen	sympathetic	alpha	contraction
Adrenal medulla	sympathetic	-	adrenaline and noradrenaline secreted into the bloodstream
Liver	sympathetic	beta	break down of glycogen (glyogenolysis)
Gall Bladder	sympathetic parasympathetic	beta muscarinic	relaxation contraction
Pancreas	sympathetic	alpha beta	inhibition of insulin secretion stimulation of insulin secretion
Descending colon	sympathetic parasympathetic	alpha beta muscarinic	vasoconstriction inhibition of peristalsis and secretion peristalsis and secretion
Sigmoid colon, rectum and anus	sympathetic parasympathetic	alpha beta muscarinic	constriction of sphincter muscles inhibition of peristalsis and secretion peristalsis and secretion
Bladder	sympathetic parasympathetic	alpha beta muscarinic	contraction of sphincter relaxation of detrusor muscle contraction of detrusor muscle
Penis	sympathetic parasympathetic	- muscarinic	ejaculation erection
Clitoris	parasympathetic	muscarinic	erection
Uterus	sympathetic	alpha beta	contraction relaxation
Blood vessels in:
Skin	sympathetic	alpha	constriction
Mucosal linings	sympathetic	alpha	constriction
Muscle	sympathetic	cholinergic	dilation
Kidneys	sympathetic	alpha	constriction
Lungs	sympathetic	alpha	constriction
Intracranial	sympathetic	alpha	slight constriction

sweat glands except palm of hands	sympathetic	muscarinic	sweating
sweat glands on palms of hands	sympathetic	alpha	sweating
Pilomotor muscles at root of body hair	sympathetic	alpha	piloerection (making hair "stand on end") horripilation ("goose pimples")
Adipose tissue	sympathetic	beta	lipolysis (break down of fat to release energy)

The table below shows some of the effects of drugs upon the Autonomic Nervous System.

Table 4 : Drugs and the ANS

Drug How it works Clinical use

Sympathomimetic drugs (also called adrenergic drugs) they mimic the effects of the SyNS

Adrenaline (e.g. Medihaler-Epi, Lignostab, Eppy, Xylocaine) acts directly on both alpha and beta receptors Used in asthma and other allergic diseases it relaxes airways and reduces swelling.

Pseudoephedrine (Dimotane Co) causes release of noradrenaline Used as treatment for rhinitis and colds as a decongestant.

Phenylephrine (Decohist, Novahistine) acts directly on alpha receptors constricting small blood vessels in the lining of the nose thus relieving congestion Used as a decongestant in rhinitis and colds

Amphetamines including MDMA (Ecstasy) causes accumulation of noradrenaline at the synapses No longer used clinically except for treatment of narcolepsy and attention deficiency hyperkinesis where two proprietary brands include Dexadrine and Ferndex

Adrenergic Blocking Drugs

Reserpine (Direserpine) blocks the synthesis and storage of noradrenaline Used in the management of some types of hypertension. Sometimes used for treatment of psychosis in individuals who cannot tolerate phenothiazines. Not available in the UK

Propanolol (Inderal) blocks beta receptors Used in hypertension, angina, migraine headaches and mitral valve prolapse.

Cholinomimetic Drugs also called parasympathomimetic drugs they mimic the effects of acetylcholine and the parasympathetic nervous system

Pilocarpine (Isopto- carpine, Sno Pilo) acts directly on muscarinic receptors used as eye drops in ophthalmology to constrict the iris of the eye. Used in the treatment of glaucoma

Cholinergic blocking drugs also called anticholinergic drugs

Atropine (Lomotil, Atrosept) blocks the action of acetylcholine on muscarinic receptors Used in the treatment of diarrhoea (Lomotil) as it can slow down peristalsis. Used as a pre-op as it can prohibit the secretion of mucous and fluids which could block the airways. Use in the treatment of people who have been exposed to nerve gases or pesticides with anti-cholinesterase properties. Used in the relief of pain in urinary tract infections (UTI's) (Atrosept)

Scopolamine (Buscopan, Joy-Rides, Kwells) blocks the action of acetylcholine on muscarinic receptors Used in small doses in the alleviation of the symptoms of motion sickness. Can be used to promote twilight sleep (drowsiness with amnesia) in labour.

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Table 4 : Drugs and the ANS
Drug	How it works	Clinical use
Sympathomimetic drugs (also called adrenergic drugs) they mimic the effects of the SyNS
Adrenaline (e.g. Medihaler-Epi, Lignostab, Eppy, Xylocaine)	acts directly on both alpha and beta receptors	Used in asthma and other allergic diseases it relaxes airways and reduces swelling.
Pseudoephedrine (Dimotane Co)	causes release of noradrenaline	Used as treatment for rhinitis and colds as a decongestant.
Phenylephrine (Decohist, Novahistine)	acts directly on alpha receptors constricting small blood vessels in the lining of the nose thus relieving congestion	Used as a decongestant in rhinitis and colds
Amphetamines including MDMA (Ecstasy)	causes accumulation of noradrenaline at the synapses	No longer used clinically except for treatment of narcolepsy and attention deficiency hyperkinesis where two proprietary brands include Dexadrine and Ferndex
Adrenergic Blocking Drugs
Reserpine (Direserpine)	blocks the synthesis and storage of noradrenaline	Used in the management of some types of hypertension. Sometimes used for treatment of psychosis in individuals who cannot tolerate phenothiazines. Not available in the UK
Propanolol (Inderal)	blocks beta receptors	Used in hypertension, angina, migraine headaches and mitral valve prolapse.
Cholinomimetic Drugs also called parasympathomimetic drugs they mimic the effects of acetylcholine and the parasympathetic nervous system
Pilocarpine (Isopto- carpine, Sno Pilo)	acts directly on muscarinic receptors	used as eye drops in ophthalmology to constrict the iris of the eye. Used in the treatment of glaucoma
Cholinergic blocking drugs also called anticholinergic drugs
Atropine (Lomotil, Atrosept)	blocks the action of acetylcholine on muscarinic receptors	Used in the treatment of diarrhoea (Lomotil) as it can slow down peristalsis. Used as a pre-op as it can prohibit the secretion of mucous and fluids which could block the airways. Use in the treatment of people who have been exposed to nerve gases or pesticides with anti-cholinesterase properties. Used in the relief of pain in urinary tract infections (UTI's) (Atrosept)
Scopolamine (Buscopan, Joy-Rides, Kwells)	blocks the action of acetylcholine on muscarinic receptors	Used in small doses in the alleviation of the symptoms of motion sickness. Can be used to promote twilight sleep (drowsiness with amnesia) in labour.

Last updated on april 5th 1998
Authored by John Ross, Lecturer at the University of Luton, Faculty of Healthcare and Social Studies

e-mail johnross@mcmail.com