ANS Flashcards
Where does the sympathetic divisions of the ANS arrise from?
Thorasic and Lumbar regions
- cell bodies in lateral horn
- synapse with post in paravertable chain
Where does the parasympathetic regions of the ANS arrise from?
Cravinal and Sacral regions of th evertebral column
- Ganglia lie close to target organs
What the the pre-ganglionic neurtransmitters?
Para- ACh
Sympa- ACh
What are the post ganglionic neurotransmitters?
Para- ACh
Sympa- Noradrenaline
What are the post ganglionic receptors for ACh?
Muscarinic receptors;
- M1/2/3
- QIQ
GPCRs
What are the post ganglionic receptors for noradrenaline?
Adrenoreceptors;
- a1/a1/b1/b2
- QISS
What sympathetic postganglions don’t use noradrenaline?
Sweat glands
Piloecector muscles
Use Ach on muscarinic
What is the parasympathetic effects on the heart?
M2 receptors:
SA node- Bradycardia
AV node- reduce conductance volicity
What are the sympathetic affects on the heart?
B1 receptors:
SA node- Tachycardia
Ventricles- Positive inotropy
What is the sympathetic actions on the arteries?
A1 receptors:
Arteriolar contraction/ venous contraction
B2 receptors:
Arteriolar relaxation in some vascular beds
What are the parasympathetic effects on the bronchiolar smooth muscle?
M3 receptors:
Bronchiolar contraction
What are the sympathetic effects on the bronchiolar smooth mucle?
B2 receptors:
Bronchiolar relaxation
What are the basic steps in neurotransmission?
1- uptake precoursers 2- synthesis of transmitter 3-vesicular storage of transmitter 4-degradation of transmitter 5-depolarisation due to apot 6-depolarisation dependant ca influx 7-exocytotic relsease of transmitter 8- diffusion to post memb 9-interaction post memb receptors 10-inactivation of transmitter 11-re-uptake of transmitter 12-interaction with pre receptors
How do Muscarinic cholinoreceptor agonists act?
Vary in selectivity and resistance to degradation by choline esterase
Major clinical use- Glaucoma
How do nicotinic cholinoceptor antagonists act?
May have a preferential ganglion or nm blocking action
How do muscarinc cholinoceptor antagonists act?
Little sensitivity to subtypes
Vary in peripheral vs central actions
Reduce parasympathetic activity
What is ACh synthasied from?
Choline and CoA by choline acetyle transferase
How do drugs intefere with cholinergic transmission?
- Interactions woth Cholinoreceptors
- cholinesterase inhibitors (decreases the rate ACH degrated so prolongs time ACh in cleft)
What is noradrenaline synthasised from?
Tyrosine within nerve terminal
Tyrosine Hydroxylase (rate limiting enzyme)
How is adrenaline synthasised?
Due to phenylethanolamine N-methyltransferase in chromaffin cells of adrenal medulla.
How is adrenergic (noradrenaline) transmission limited?
Uptake 1- high affinity system
-rapildly reducing amount of noradrenaline in cleft
Uptake 2- lower affinity system
- if escapes the cleft
- can be re-vesiculated or metabololised
How do adrenoceptor agonists assert an effect?
Highly selective to receptor subtype
Affect relates to what receptor acting on
Eg A1/2 or B1/2
How do adrenoceptor antagonists cause an effect?
Are normally just A or B selective
Appose the effect binding to the receptor normally causes
How do uptake 1 inhibitors cause an effect?
Centerally exert actions
Noradrenaline remains in cleft longer so adrenic effects produced
