Sympathetic Parasympathetic Action Prepares body for an emergency Conserves ...
Sympathetic
|
Parasympathetic
| |
| Action |
Prepares body for an emergency
|
Conserves & restore energy
|
| Outflow |
T1 – L2 spinal segments (Lateral grey column)
|
Cranial nerves III, VII, IX, X and S2,3,4
|
| Pre – ganglionic fibers |
Myelinated
| |
| Ganglia | Para vertebral (Sympathetic trunks) Pre vertebral (Celiac, Superior & inferior mesenteric) | Small ganglia close to viscera (Ciliary, Otic) Ganglion cells in plexus (Cardiac, pulmonary) |
| Neurotransmitter within the ganglia |
Acetylcholine
| |
| Ganglion blocking agent |
Hexamethonium & Tetraethyl ammonium (Compete with Ach)
| |
| Post – ganglionic fibers | Long Non myelinated | Short Non myelinated |
| Characteristic activity | Widespread due to many post ganglionic fibers Liberation of epinephrine & nor epinephrine from supra renal medulla |
Discrete action with few post ganglionic fibers
|
| Neurotransmitter at post ganglionic endings | Nor epinephrine at most endings Ach in few endings (Sweat glands) |
Ach at all ends
|
| Blocking agents on receptors of effector cells | Alpha adrenergic receptors – Phenoxybenzamine Beta adrenergic receptors – Propranolol | Atropine Scopolamine |
| Agents inhibiting synthesis & storage of neurotransmitter at post ganglionic endings |
Reserpine
| |
| Agents inhibiting hydrolysis of neurotransmitter at sites of effector cells |
Acetylcholine esterase blockers (Neostigmine)
| |
| Drugs which mimic autonomic activity | Sympathomimetic drugs α receptors – Phenylephrine β receptors – Isoproterenol | Parasympathomimetic drugs Pilocarpine Methacholine |
| Higher control |
Hypothalamus
| |
Autonomic innervations
| Organ | Sympathetic action | Parasympathetic action | |
| Eye | Pupil | Dilates | Contracts |
| Ciliary muscles | Relaxes | Contracts | |
| Glands | Lacrimal, Parotid, Submandibular, Sublingual & Nasal | Reduce secretions (By vasoconstriction of blood vessels) | Increase secretions |
| Sweat | Increase secretions | ||
| Heart | Cardiac muscles | Increase force of contraction | Decrease force of contraction |
| Coronary arteries | α receptors – Constricts β receptors – Dilates | ||
| Lungs | Bronchial muscles | Relaxes (Dilates bronchi) | Contracts (Constricts bronchi) |
| Bronchial secretions | Increase secretions | ||
| Bronchial arteries | Constricts | Dilates | |
| GIT | Muscles in walls | Decrease peristalsis | Increase peristalsis |
| Muscles in sphincters | Contracts | Relaxes | |
| Glands | Reduce secretions (By vasoconstriction of blood vessels) | Increase secretions | |
| Liver | Breaks down glycogen into glucose | ||
| Gall bladder | Relaxes | Contracts | |
| GUT | Bladder wall (Detrusor) | Relaxes | Contracts |
| Sphincter vesicae | Contracts | Relaxes | |
| Kidney | Decrease output due to constriction of arteries | ||
| Erectile tissue of penis & clitoris | Causes erection (relaxes erectile tissue) | ||
| Ejaculation | Contracts SM of vas deferens, seminal vesicles & prostate | ||
| Systemic arteries | Skin | Contracts | |
| Abdominal | Contracts | ||
| Muscle | α receptors – Constricts β receptors – Dilates Dilate (Cholinergic) | ||
| Skin | Erector pili muscles | Contracts | |
| Supra renal gland | Cortex | Stimulates | |
| Medulla | Liberate epinephrine & nor epinephrine | ||
