Drugs and PNS Flashcards
3 components of PNS?
Efferent or afferent
Autonomic (E), somatic (E), sensory (A)
How does sympathetic NS affect
a) pupils
b) respiratory rate
c) heart rate
d) blood flow to visceral organs
e) salivary secretions
a) dilate
b) increase
c) increase
d) increase
e) decrease
How does parasympathetic NS affect
a) pupils
b) respiratory rate
c) heart rate
d) blood flow to visceral organs
e) salivary secretions
a) constrict
b) decrease
c) decrease
d) decrease
e) increase
Describe sympathetic fibres?
Short preganglionic fibre - Ach as NT
Long post-ganglionic fibre - NA as NT
Describe parasympathetic fibres?
Long pre-ganglionic fibre - Ach as NT
short post-ganglionic fibres - Ach as NT
Describe somatic fibres?
Single fibre terminating at NMJ, Ach as NT
How do sweat glands and adrenal glands show exceptions to these rules?
Both sympathetic fibres but
Sweat glands = Ach at synapse to target not NT
Adrenal glands = single fibre using Ach
How is acetyl choline made?
Choline transported into fibre
Choline to Ach via cholineacyetyl transferase (CAT)
How is Ach stored and released?
Vesicles exocytosis
What type of receptor does Ach interact with?
Muscarinic or nicotinic
How is Ach terminated?
Acetylcholinesterase (breaks down into choline and acetate)
Name muscarinic receptor subtypes?
M1 2 3
Where are muscarinic receptors found?
Post-ganglionic parasympathetic synapses
What type of receptors are muscarinic?
G coupled
What are nicotinic receptor subtypes?
Neuronal and muscular
Where are neuronal nicotinic receptors?
Preganglionic sympathetic and parasympathetic synapses
Where are muscular nicotinic receptors found?
NMJ (somatic)
What type of receptor is nicotinic?
Ligand gated ion channel
Action of muscarinic antagonists?
Activate parasympathetic nervous system
2 uses of muscarinic agonist and name the drug?
Pilocarpine
Treat glaucoma - pupil contraction
Treat xerostomia - increase saliva flow
Use of the muscarinic antagonists
a) Atropine
b) Tropicamide
c) Ipratroprium
d) Hyoscine
a) Treats bradycardia by inhibiting decrease in heart rate
b) Pupil dilation in surgery
c) treat asthma
d) decrease gastric motility and motion sickness
Effect of nicotinic agonist at NMJ?
Example
Suxemethonium
Initial depolarisation and muscle fibre contraction (twitch)
Because agonist is not metabolised rapidly by acetylcholinesterase the fibre is constantly depolarised = depolarising block
Paralysis and muscle contraction for surgery
Effect of nicotinic antagonist at NMJ?
Example
Tubocurarine Hyperpolarisation Inhibition of depolarisation Non-depolarising block Paralysis for surgery
What is the main use for nicotinic antagonists and agonists?
Paralysis for surgery
Name 4 muscarinic antagonists and their uses?
Atropine - treat bradycardia
Tropicamide - pupil dilation during surgery
ipratroprium - treat asthma
Hyoscine - treat motion sickness (decrease gastric motility)
Name the type of drug g that inhibits acetylcholinesterase
anticholinesterases
How do anticholinesterases effect autonomic nervous system?
Increased transmission at parasympathetic post-ganglionic synapses = increase parasympathetic effects
How do anticholinesterases effect NMJ?
Increased muscle tension and twitching (depolarising block at large doses)
Name an anti cholinesterase and its use?
Neostigmine
Myastheia gravis
Induce paralysis for surgery
