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26 Cards in this Set
- Front
- Back
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In the sympathetic nervous system, where are the ganglia located?
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Paravertebral ganglia
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What type of NT do post- ganglionic neurons use in SNS?
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Adrenergic/ cholinergic (mACHR)
In the adrenal medulla, there are no postganglionic neurons, act at nACHR on chromaffin cells to release adrenalin into the blood stream |
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Where are the ganglia in the PNS?
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Near/ within end organs
Cholinergic (mACHR) |
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What are the 2 different sites of action of drugs in the ANS?
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Direct acting - agonist/ antagonist at receptors
Indirect acting by altering NT levels (Inhibiting ACH synthesis, release, degradation) |
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Give an example of a ganglionic stimulator and what it causes?
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nACHR agonists- Nicotine/ Suxamethonium
Used for depolarising neuromuscular block Increases HR and BP, salivation and contractility of the gut = nausea, diarrhoea and vomiting Prolonged exposure = nACHR desensitisation = inhibition of the ANS |
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Give an example of a ganglionic blocker?
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nACHR antagonist- Mecamylamine
For hypertension but to many AEs! Curare and a- Bungarotoxin act at both ganglia and neuromuscular junction |
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What causes ACH release inhibition?
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Botulinium toxin
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Give 2 examples of ACH degradation inhibitors?
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Carbamates (reversible)
Organophoshpates (irreversible) - nerve gases (sarin, soman, vx), Insecticides (malothion, parathion) |
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What happens in overdose? SLUDGEM
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Salivation
Lacrimation Urination Defectation GI upset Emesis Miosis (Antidote = atropine- muscarinic antagonist) |
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Name 4 disorders helped by cholinesterase inhibitors?
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Glaucoma (causes contraction of ciliary body to increase outflow of aqueous humour)
Myasthenia gravis Ileus/ urinary retention Alzheimers (facilitates memory) E.g Neostigmine/ pyridostigmine (longer acting) |
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What are the effects of a muscarinic agonist?
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Increases emptying of the bladder, GI tract and salivary glands
Decreases sweating, lacrimation, HR, BP, Intraocular pressure |
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Give examples of muscarinic agonists?
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Bethanechol - urinary retention
Pilocarpine - dry mouth/ glaucoma |
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What are the effects of muscarinic antagonists?
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Increased HR
Blurred vision (decreased accommodation) Hot dry skin Decreased GI motility Independent of the ANS - Delirium/ confusion |
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What causes pupil dilation (drug)
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Tropicamide (muscarinic antagonist)
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Why are muscarinic antagonists used in surgery?
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Adjuncts in anaesthesia
Atropine - pre operative and sedation Ipratroprium brominde - Decreases bronchial and pharyngeal secretions |
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How can NA activity be affected?
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Agonists/ NA transport blocers - sympathomimetic
Antagonists - sympatholytic |
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What does stimulation of a1 cause?
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Artery and vein constriction in the heart, pupillary dilator muscle and prostate
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What does stimulation of a2 cause?
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Inhibitory autoreceptor - activation decreases sympathetic activity in the CNS, platelets, nerve terminals, SM, fat cells
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What doe stimulation of B1 cause?
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Increased heart rate and contractile force
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What does stimulation of B2 cause?
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Bronchodilation, vasodilation, also affects the liver and skeletal muscle
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What cells do B3 affect?
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Fat cells
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Name 3 drugs that alter NA release, reuptake and breakdown (SNS)
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Cocaine- inhibits reuptake
Amphetamines - increases release Pargyline - antidepressant/ antihypertensive |
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What does Pargyline do?
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Inhibits MAO B which catabolises NA and DA
This increases dopamine and displaces NA from the nerve terminal Resulting in paradoxial hypertension due to decreased sympathetic activation of NA |
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Name 2 agonists and 1 antagonist for A1
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Agonist= phenylephrine + Midrodrine (hypotension)
Antagonist= Prazosin (hypertension) |
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Name an agonist and antagonist for A2
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Agonist = clonidine (decreased sympathetic activity)
Antagonist = yohimbine (increased sympathetic activity) Generally used for opiate withdrawal/ ADHD/ Tourrettes/ Hypertension |
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Name 2 agonists and 2 antagonists of Beta receptors
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Agonist - Isoproterenol (increases HR and contractile force) (non selective B1/2)
Agonist - Salbutamol (bronchodilation B2) Antagonist - Propranolol (hypertension, decreases sympathetic tone, non selecective B1/2) Antagonist - Atenolol (Hypertension, angina, arrythmias, B1) |
