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40 Cards in this Set
- Front
- Back
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what are neuromodulators?
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chemicals released by neurons that have little or no direct effects on their own but that modulate the effect of neurotransmitters
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what are the monoamine neurotransmitters (3 examples)
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ACh
serotonin histamine |
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what are the 3 catecholamine neurotransmitters?
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dopamine
NAd adrenaline |
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what are 3 amino acid neurotransmitters?
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glutamate
GABA glycine |
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what are 3 examples of large molecule neurotransmitters?
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peptides eg
substance P encephalin vasopressin |
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what are the two classes of ACh receptors?
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muscarinic
nicotinic |
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what are the stimulatory actions of ACh on smooth muscle & glands called?
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muscarinic actions
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what blocks muscarinic receptors?
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atropine
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why are nicotinic receptors so called & how do they respond to muscarinic blockers?
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because the actions of ACh at these receptors are mimicked by nicotine
nil effect of atropine at these receptors |
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what affect does small dose ACh have at nicotinic receptors?
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stimulate postganglionic neurons
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what effect does large dose ACh have at nicotinic receptors?
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blocks transmission of impulses from pre to postganglionic neurons
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how do nicotinic & muscarinic receptors differ structurally?
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nicotinic are ligand gated ion channels
muscarinic - g proteins |
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where is serotonin most commonly found? (3)
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platelets
GI tract (enterochromaffin cells & myenteric plexus) brainstem (midline raphe nuclei) |
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how is serotonin formed?
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hydroxylation and decarboxylation of tryptophan
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what is the principal urinary metabolite of serotonin? how is it clinically used?
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5-HIAA
used as an index of rate of serotonin metabolism in the body |
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what happens to serotonin after it's reuptook?
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inactivated by MAO to 5-HIAA which is then excreted in the urine
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how does tryptophan differ from CNS & periphery?
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coded by a different gene so can be a knockout for one and not the other
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what kinds of receptors are serotonin receptors?
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G proteins except 5HT3 which is ligand gated
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how do we measure serotonin in the body?
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5-HIAA in the urine
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at what serotonin receptors do anti emetics work?
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5HT3
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at what serotonin receptors do which migraine agents work?
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5HT1
sumatriptan & other triptans |
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are SSRIs agonists or antagonists?
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agonists because they prevent reuptake
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what is an example of serotonergic antagonists used in clinical practice?
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ondansetron etc are 5HT3 blockers
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what transmitter is present at most sympathetic postganglionic endings?
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Nad
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what characterises vesicles containing Nad?
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they have a dense core
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how are the catecholamines formed?
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hydroxylation & decarboxylation of tyrosine
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which receptors do NAd vs adrenaline have more affinity for?
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alpha receptors - NAd
beta receptors - adrenaline |
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what kind of receptors are alpha and beta adrenergic receptors?
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G protein coupled
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to what other receptors are alpha & beta receptors closely related?
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dopamine
serotonin muscarininic Ach |
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how is ACh released?
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SNAP and VAMP proteins open the vesicle pore to the outside space, releasing stored transmitter
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where does botulinum toxin work?
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enzymatically alters a VAMP or other protein to prevent ACh release
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how is release & termination of action of dopamine & NAd similar/different to ACh?
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both release by Ca++ dependent mechanism
but cholinergics are metabolised wherease adrenergics rely on reuptake |
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what effect do amphetamines have on catecholamine release?
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promote it
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what is the mnemonic for remembering nicotinic effects?
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MTWTF (days of week):
Mydriasis/ Muscle cramps Tachycardia Weakness Twitching Hypertension/ Hyperglycemia Fasiculation |
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what is the mnemonic for remembering muscarinic effects?
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SLUG BAM:
Salivation/ Secretions/ Sweating Lacrimation Urination Gastrointestinal upset Bradycardia/ Bronchoconstriction/ Bowel movement Abdominal cramps/ Anorexia Miosis |
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how many subtypes of GABA receptors are there & where are they found?
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3
GABA A & B in CNS GABA C in retina |
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what kind of receptors are GABA?
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A & C are ion channels admitting Cl- in
B is a G protein that opens K+ channels (ie drives K+ out), inhibits adenylyl cyclase & inhibits Ca++ |
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how do benzodiazepines relate to GABA?
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bind to alpha subunits & potential Cl- conductance
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what is the chief inhibitory neurotransmitter in the CNS?
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GABA
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how does flumazenil relate to GABA?
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GABA antagonist
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