Introduction to autonomic nervous system
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Transcript of Introduction to autonomic nervous system
Introduction to Autonomic Nervous System
1
By Dr. Dipesh R. Panday, Department of Clinical Pharmacology &Therapeutics
28/09/2012
Relay-station
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Ganglion: a mass of nerve cellbodies outside CNS
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Most organs receive dual sympatheticand parasympathetic innervation.
However, some organs only receive sympathetic innervation:SpleenSweat GlandsPiloerector MusclesMost Blood Vessels
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Cholinergic Neuroeffector Junction
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Hemicholinium
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Botulinum toxin
CHOLINOMIMETICS
Nicotinic: NicotineMuscarinic: Bethanechol, PilocarpineAChE inhibitors: reversible-edrophoniumAChE inhibitors: irreversible-OP poison
CHOLINORECPTOR BLOCKERSMuscarinic: Atropine, Benztropine, Tropicamide,Glycopyrrolate, ScopolamineNicotinic (NM): Tubocurarine, Atracurium, SuccinylcholineNicotinic (NN): Hexamethonium, Mecamylamine
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α1 action• Eye-radial (dilator) muscle• Decongestant • Arterioles-contraction(increases BP)• Bladder trigone and sphincter-contraction(anti-diuretic)• Glycogenolysis
• Drugs with selective α1 action: – Oxymethazoline– Phenylephrine– Methoxamine– Dopamine at therapeutic dose.
• α1 selective blocker: Prazosin, Doxazosin, Terazosin, Amsulosin• α nonselective blocker::
Phentolamine(nonselective,irreversible),Phenoxybenzamine(nonselective,irreversible)
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α2 action
• Decrease BP by autoregulation
• Drugs with selective α2 action
– Clonidine
– α -Methyldopa
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β Action• β1 Action: Ionotropic, Dromotropic, Chronotropic action on heart
muscle.
• β2 action((mostly not innervated)– Vasodilation– Bronchioles relaxation– Uterus relaxation
• Preparations:• β agonists:Dobutamine (β1 > β2 ), Isoproterenol (β1 = β2 )
• β2 agonists: Salbutamol, Albuterol, Terbutaline, Ritodrine
• Mixed:Norepinephrine (α1, α2 β1,),Epinephrine (α1, α2, β1, β2)
• β1 (cardioselective) antagonists: Acebutolol, Atenolol, Esmolol• NOTE:Use of Epinephrine: Anaphylaxis, Cardiac Arrest
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Cholinergic Receptor Activators
• Direct activators
• Bethanechol (M), Methacholine, Nicotine (N), Pilocarpine(M)
• Indirect activators
– AChE inhibitors: reversible- Edrophonium, Physostigmine, Neostigmine
– AChE inhibitors: irreversible- Organo-phosphate Poison, Malathion, Parathion
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Cholinergic Receptor Antagonists• Muscarinic blockers: Atropine, Benztropine,
Ipratropium, Glycopyrrolate, Scopolamine
• Ganglionic blockers:Hexamethonium, Mecamylamine
• NMJ blockers:
• Depolarizing: Atracurium, Pancuronium, Tubocurarine
• Nondepolarizing: Succinylcholine2728/09/2012
Adrenergic Receptor Activators
• α1 agonists: Phenylephrine, Methoxamine
• α2 agonists : Clonidine, A-methyldopa
• β agonists: Isoproterenol (β1 = β2 ), Dobutamine (β1 > β2 )
• β2 agonists: Salbutamol,Albuterol, Ritodrine, Terbutaline
• Mixed: Norepinephrine (α1, α2, β1,), Epinephrine (α1, α2 β1, β2)
• Indirect-acting: Amphetamine, Cocaine, Ephedrine2828/09/2012
Adrenergic Receptor Antagonists• α1 antagonists: Doxazosin, Prazosin, Terazosin
• α2 antagonists: Yohimbine
• Mixed α antagonists: Phenoxybenzamine, Phentolamine
• β1 (cardioselective) antagonists: Acebutolol, Atenolol, Esmolol, Metoprolol
• β(nonselective): Pindolol, Propranolol, Timolol
• α & β antagonists: Carvedilol, Labetalol2928/09/2012