Flashcards in The Autonomic Nervous System Deck (37):
What are the 5 regions of the brain stem/spinal cord, starting superiorly?
Which region of the spinal cord do sympathetic nerve fibres stem from?
What part of the spinal cord do parasympathetic nerve fibres stem from?
Where is the vagus nerve found? What does it control?
In the medullary region
Controls heart rate
Where are parasympathetic ganglia located?
In the innervated tissues
Where are sympathetic ganglia located?
In the paravertebral chain, near the spinal cord
What are the structures of the preganglionic and postganglionic parasympathetic nerve fibres?
Preganglionic = long myelinated
Postganglionic = short unmyelinated
What are the structures of the preganglionic and postganglionic nerve fibres in the sympathetic nervous system?
Preganglionic = short myelinated
Postganglionic = long unmyelinated
What are the primary neurotransmitters of the ANS?
All preganglionic neurones in the ANS use which neurotransmitter?
What receptors does ACh work on at preganglionic neurone synapses?
Nicotinic ACh receptors
What types of receptors are nicotinic ACh receptors?
Ligand gated ion channels
What neurotransmitter and receptors are found at postganglionic parasympathetic neurones?
Muscarinic ACh receptors
What are the subtypes of muscarinic ACh receptors? What type of receptor is it?
m1 to m5
What neurotransmitter and receptors are found at postganglionic sympathetic neurones?
What subtypes of adrenoceptors exist? What type of receptor is it?
A1,a2, b1, b2, b3
Are all sympathetic postganglionic neurones adrenergic?
No some are cholinergic
E.g. Those innervating sweat glands, hair follicles
What other neurotransmitters are found in the ANS?
NANC transmitters such as NO and ATP are found in the ANS
Usually correlated with ACh or NA
What do chromaffin cells release?
What results in the release of neurotransmitter at synapses?
Depolarisation dependent influx of calcium ions
How is ACh synthesised? Which enzyme catalyses the reaction?
Acetyl coA + choline ----> Acetycholine + coenzyme A
How is acetylcholine degraded? Which enzyme catalyses this reaction?
Acetylcholine ----> choline + acetate
What is trimethaphan used for?
Used in hypertensive emergencies and in surgery to block nAChRs
What is tolterodine?
A m3 antagonist --> used to treat an overactive bladder
Give an example of an acetylcholinesterase inhibitor?
Donepezil to treat Alzheimer's disease
What is SLUDGE a mnemonic for?
The effects of massive discharge of the parasympathetic nervous system - chronic over stimulation of mAChRs
What does SLUDGE stand for?
What is lacrimation and emesis?
When is SLUDGE encountered?
When there has been;
Magic mushroom ingestion
Exposure to insecticides
What is the treatment for SLUDGE?
Both anti-cholinergic agents
Give an example of mAChR agonists and what they are used to treat?
Pilocarpine - treat glaucoma
Bethanecol - stimulate bladder emptying
Give an example of mAChR antagonists and what they are used to treat?
Ipratropium - asthma and COPD
Tolterodine - overactive bladder
What is the structure of post ganglionic sympathetic neurones?
They are highly branched and consist of bulges called varicosities where NA can be released
How is NA synthesised? Which enzymes are used?
Tyrosine --> DOPA ---> Dopamine---> NA
1) tyrosine hydroxylase
2) dopa decarboxylase
3) dopamine b-hydroxylase
What happens following calcium-dependent release of NA?
NA diffuses across the synaptic cleft
Binds with postsynaptic adrenoceptors initiating the signal
Binds with presynaptic adrenoceptors regulating NA release
How is NA degraded in the synaptic cleft?
Removed by NA transporter proteins
1) removed by high affinity Na+ dependent transporter
2) remaining NA removed by low affinity neuronal mechanism