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| 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. |
Last updated on Wednesday, 07 April 1999 11:16 +0100
