Int 3: Autonomic Nervous System Flashcards
What subset of neurons does the a)PSNS and b)SNS use?
a) Cholinergic
b) Noradrenergic
There are 2 exceptions to the SNS adrenergic neuron rule. One is in the sweat glands and one is in the Adrenal medulla. What are the receptors at each location?
a) Sweat glands: Muscarinic ACh receptors
b) Adrenal medulla (+ between sweat glands and spinal chord): Nicotinic ACh receptors
What are the physical characteristics / differences of a) PSNS ganglionic neurons and b) SNS ganglionic neurons (think length)
a) PSNS pre-ganglionic neurons are LONG, synapsing close to target organs, releasing ACh to act on muscarinic receptors
b) SNS pre-ganglionic neurons are SHORT, synapsing close to spinal column, releasing noradrenaline to act on adrenergic receptors (2 exceptions)
ACh receptors can be divided into 2 classes, what are they?
Muscarinic (7 domain G-protein coupled)
Nicotinic (ligand-gated ion channels): subtypes = skeletal NMJ, ganglionic and neuronal
There are 5 main subtypes of muscarinic receptor (M1-M5) of which 3 have distinct functions / loci - M1, M2 and M3. What are their functions?
M1 - Neural (slow EPSP)
M2 - Cardiac
M3 - Glandular secretion, contraction of visceral smooth muscle, vascular relaxation
Which of the below enzymes synthesises / degrades acetylcholine?
a) Acetylcholinesterase
b) Choline acetyltransferase
a) degrades
b) synthesises
This is hard but what 4 things can muscarinic receptors do?
Clues:
a) activate…
b) inhibit…
c) open….
d) inhibit…
- adenylate cyclase
- Ca++ channels
- Phospholipase C
- K+ channels
a) Activate phospholipase C leading to production of IP3 (releases intracellular Ca++) and diacyl glycerol - M1, M3, M5
b) Inhibit adenylate cyclase - decreasing levels of cAMP - M2, M4
c) Open K+ channels - M2
d) Inhibit Ca++ channels - M2
What parasympathomimetics or cholinomimetics?
Drugs that activate muscarinic acetylcholine receptors. They can be direct or indirect (reversible/irreversible)
Which of the following are REVERSIBLE inhibitors of ACh-esterase and which are IRREVERSIBLE inhibitors of ACh-esterase?
a) Organophosphates
b) Physostigmine
c) Neostigmine
a) Irreversible
b) Reversible
c) Reversible
Categorise the following effects of Cholinomimetic drugs into either Direct or Indirect acting:
a) Have CNS effects if permeable to blood-brain barrier
b) Have mainly muscarinic effects at end effectors
c) Have muscarinic, ganglionic and skeletal muscle effects
d) Plank alkaloids can enter CNS
e) Most synthetic drugs of this kind do not have CNS effects
f) Potentiate transmission at all cholinergic junctions
a) Indirect
b) Direct
c) Indirect
d) Direct
e) Direct
f) Indirect
What are the two therapeutic uses for cholinomimetics and what are their treatments?
- Glaucoma: Pilocarpine, Ecothiophate (indirect)
- Intestinal/urinal bladder atony: Bethanecol, Neostigmine (indirect)
What is atropine?
Muscarinic antagonist.
All functions mediated by muscarinic receptors are blocked by these drugs.
Little effect on ganglion and skeletal muscle nicotinic receptors
What are some therapeutic uses of atropine?
- Pre-anaesthetic medication
- Ophthalmological uses
- Gastrointestinal antispasmodic agents
- Treatment of poisoning by cholinomimetics
Below is the order of synthesis of noradrenaline. Match the enzymes to the stages:
- L-tyrosine uptake into synapse
1) - L-DOPA
2) - Dopamine
3)
Noradrenaline stored in vesicles - DOPA decarboxylase
- Tyrosine hydroxylase
- Dopamine beta-hydroxylase
upon writing that is gonna be really easy
1) Tyrosine
2) DOPA
3) Dopamine
There are 2 CLASSES of adrenoreceptors: Alpha and Beta.
These are divides into 2 and 3 subclasses respectively. What are their functions?
alpha-1: Smooth muscle contraction
alpha-2: Inhibition of transmitter release
beta-1-3: Heart muscle contraction, smooth muscle relaxation, glycogenesis
