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Pharmacology of the ANS 3 tutorial

Terms in this set (25)

TRUE/FALSE questions:
...
1. The somatic nervous system has pre-ganglionic and post-ganglionic nerves.
F - Only parasympathetic and sympathetic ANS have ganglia
2. Acetylcholine (ACh) stimulates muscarinic and nicotinic receptors.
T - ACh is an agonist on both types of cholinergic receptors
3. ACh is the transmitter at both parasympathetic and sympathetic ganglia.
True
4. The post-synaptic receptors innervated by parasympathetic post-ganglionic nerves are nicotinic receptors.
F - they are muscarinic receptors
5. Parasympathetic nerve activity causes sweating by releasing ACh at sweat glands.
F - nerves releasing ACh are sympathetic nerves
6. Noradrenaline only activates alpha-adrenoceptors while adrenaline only activates beta-adrenoceptors.
F - noradrenaline and adrenaline can activate alpha-adrenoreceptors and beta-adrenoreceptors
What are muscarinic receptors, where are they found and what is their physiological effect?
- cholinergic G-protein coupled receptors
- found in tissues innervated by the parasympathetic nervous system
- they are widespread and allow precise control of the individual
Before an operation, the drug atropine is sometimes given. Atropine is an antagonist which selectively blocks muscarinic receptors and prevents the neurotransmitter, acetylcholine, from stimulating them and producing an effect on the organ.
Acetylcholine released from the parasympathetic nerves slows down the heart etc. Atropine therefore opposes ACh.
What effect will atropine have on:
Heart rate?
Increase
What effect will atropine have on:
Salivary secretions?
Decrease
What effect will atropine have on:
Bronchial secretions?
Decrease
What effect will atropine have on:
Bronchial smooth muscle contractility?
Decrease
What effect will atropine have on:
Gut secretions and contractility?
Decrease
What effect will atropine have on:
Bladder emptying?
Decrease
What effect will atropine have on:
Pupil diameter?
Dilate so diameter increases
What effect will atropine have on:
Sweating?
Decrease
What effect will atropine have on receptors for acetylcholine in the ganglia and neuromuscular junction?
Atropine blocks muscarinic receptors but receptors fro ACh in the ganglia and the NMJ have nicotinic receptors. Moderate doses of atropine will have no effect on ganglia or NMJ but effects will be see if high doses are used.
Sometimes an individual might be poisoned by drugs like atropine. What effects would you expect?
Hypertension
Dizziness
Nausea
Dry mouth
Loss of balance
Lack of sweating
Blurred vision
Sensitivity to light
Lack of sweating
What could be done to counteract the effects of the poisoning? Give the type of drug used and how it works. If
Because atropine is a competitive muscarinic antagonist, effects can be reversed with a muscarinic agonist
e.g. Pilocarpine - increases availability of ACh

Use acetylcholinesterase inhibitors (AChEI) which inhibits Ache from breaking down ACh
While salmon fishing in Canada you stumble across a brown bear (Ursus arctos) weighing 800 lb and with paws the size of dinner plates. It is taking a nap in the woods. While making your hurried escape, you notice that you are experiencing a classic 'fight or flight' reaction. What are the effects of sympathetic activation on (a) the heart,
(b) the bronchial airways,
(c) the liver,
(d) blood vessels in the skin, gut and skeletal muscle, and (e) the pupil, and what are the adrenergic receptors responsible for each response?
heart - increased heart rate and force...B1 adrenoreceptor

bronchial dilation - B2 adrenoreceptor

increased glycogenolysis - B2 adrenoreceptor

blood vessels in the skin and gut vessels constrict - A1 adrenoreceptor

Dilation in skeletal muscle vessels - B2 adrenoreceptors

Pupils dilate - A1 adrenoreceptors
Clostridium botulinum is an anaerobic bacterium which may contaminate poorly sterilized tinned foods, especially meats. What is its active toxin? What effect does it have in humans? Can it ever be injected into a person for clinical purposes?
Botulinus toxin: - - Prevents the release of acetylcholine from nerves, by blocking conduction in the preterminal portion of the axon.
- Causes death by respiratory paralysis.
- Botulinus toxin may be used in local injections to treat ptosis, squint, profuse sweating, and cosmetic purposes.
The puffer fish (fugu) is a delicacy in Japan. However, it contains a deadly poison and must be prepared only by specially trained chefs. What is this poison? What does it do to nerves?
Tetrodotoxin from the gall bladder and ovary of the puffer fish.
It selectively blocks axonal conduction leading to rapid death.
In 2012, Tesco denied using Black Widow spiders to reduce the need for pesticides in its fruit orchards overseas, but such spiders occasionally turn up in baskets of supermarket fruit in the UK. What would be the effects of being bitten by a Black Widow spider?
Black Widow spiders produce latrotoxin which releases ACh from all cholinergic terminals. Effects therefore similar to poisoning with irreversible AChE inhibitors, including effects on NMJ (flaccid paralysis), PNS (secretions, diarrhoea), SNS post-ganglionic cholinergic (sweating) and SNS ganglionic (hypertension).
If a patient is untreated, what is the common mechanism of death for all three of the above?
Respiratory paralysis (asphyxia).
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