lecture 12 LOs Flashcards

1
Q

where is ACh a key NT

A

peripheral and central nervous systems

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2
Q

what does ACh do in the peripheral nervous system

A

used at all neuromuscular junctions and parasympathetic nervous systems

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3
Q

what does ACh do in the central nervous system

A

multiple cell body regions enervate cortical/subcortical regions and the ACh interneurons in the striatum

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4
Q

what is ACh made from

A

choline and acetyl coenzyme A

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5
Q

what are the components of ACh catalyzed by

A

choline and acetyl coenzyme A are catalyzed by choline acetyltransferase (ChAT)

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6
Q

where is ChAT found

A

only in neurons that use Ach

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7
Q

what is the rate of ACh synthesis controlled by

A

avaiability of precursors
rate of cell firing

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8
Q

are there selective inhibitors for ChAT

A

none have been found

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9
Q

what packages ACh into vesicles

A

vesicular ACh transporters (VAChT)

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10
Q

what does vesamicol do

A

blocks VAChT (what packages ACh into vesicles) and reduces ACh levels

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11
Q

what does black widow spider venom do

A

causes massive ACh release in the PNS
cholinergic over activity causes muscle pain, tremors, nausea, vomiting, salivation, copius sweating

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12
Q

what does botulinium toxin do to ACh

A

inhibits its release selectively in nueromuscular joints

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13
Q

does ACh undergo direct reuptake

A

no

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14
Q

how are ACh levels controlled

A

by acetylcholinesterase (AChE)

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15
Q

what does AChE do

A

rapidly breaks down to choline and acetic acid

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16
Q

where is AChE found

A

on post synaptic membranes and in presynaptic cells that metabolize excess ACh

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17
Q

what happens to ACh after breakdown

A

most choline is taken back into the cholinergic nerve terminal by a choline transporter

18
Q

what does hemicholinium-3 (HC-3) do

A

blocks choline transporters
reduces rate of ACh production

19
Q

what is physostigmine used for

A

crosses the blood brain barrier
certain types of ACHE-inhibitors are used to offset some of the decline in Alzheimers

20
Q

what is sarin and what does it do

A

very toxic nerve gas
causes ACh accumulation and overstimulation of cholinergic synapses throughout the CNS and PNS which leads to muscle paralysis and death by asphyxiation

21
Q

what are the two ACh receptor subypes

A

nicotinic
muscarinic

22
Q

what does the nicotinic ACh receptor subtype respond to, and what type of recepor is it

A

responds to nicotine agonist
ionotropic

23
Q

what happens in nicotnic ACh receptor when ACh binds

A

cahnnel opens
Na+ and Ca2+ enter the cell and depolarize the membrane
mediates fast excitatory responses in CNS and PNS

24
Q

how many subunits do nicotinic receptors have

A

5

25
Q

what does coninuous activation of nicotinic receptors result in

A

receptors desensitize
channel remains closed even when the agonist is bound
recovers after a short time w no stimulation

26
Q

what does prolonged activation of nicotinic receptors result in

A

depolarization block
persistent depolarization causes resting potential to be lost
cell cant be excited until agonist is removed and membrane repolarizes

27
Q

what is a nicotinic receptor agonist and what does it do

A

succinylcholine
muscle relaxant used in some surgical procedures
causes depolarization block

28
Q

what are two nicotonic receptor antagonists and what do they do

A

mecamylamine: blocks nicotinic receptors both in CNS and autonomic ganglia
d-tubocurarine: blocks muscle nicotinic receptors

29
Q

what do muscarinic receptors respond to

A

muscarine

30
Q

what types of receptors are muscarinic receptors

A

metabotropic
operate via second messenger and/or enhance K+ channel opening

31
Q

where are muscarinic receptors found peripherally

A

caridac and smooth muscle in organs as well as insulin secreting cells of pancreas

32
Q

where are M2 receptors and what do they do

A

cardiac
slows heart rate when activated
also acts as presynaptic autoreceptor in CNS

33
Q

where are M3 receptors and what do they do

A

smooth muscle
activation results in conraction (digestive tract), and mediates other sevretory responses (ex salivation)

34
Q

what is a muscarinic agonist

A

pilocarpine
parasympathomimetic agent
poisioning leads to exaggerated parasympathetic response (SLUDGE): salivation, lacrimation, urination, diarrhea, gastrointestinal distress, and emesis

35
Q

what is a muscarinic antagonist

A

atopine and scopolamine
inhibit parasympathetic effexts
dialate pupils, redue seretions that clog airways, counteract holinergic poisoning
central effects are drowsiness, euphoria, amnesia, fatigue, dreamless sleep
high does make you: blind as a bat, mad as a hatter, red as a beet, hot as hades, dry as a bone, the bowel and bladded lose their tone, and the heart runs alone

36
Q

what does ACh in the striatum do

A

regulation of movement depends on balance between ACh and DA

37
Q

what does ACh in the pons do

A

project to midbrain DA neurons
regulates DA burst firing patterns
mediated by postsynaptic niotinic and muscarinic receptors

38
Q

what does ACh in the basal forebrain cholinergic system (BFCS) do

A

intermixed with othe transmitters (GABA and glu)
plays a key role in regulating memory and cog functions mediated by forebrain regions, also facilitating attention

39
Q

attention assay for ACh in mice

A

light flashes, they press L lever, light does not flash they press R lever
if they press the wrong lever its a miss or a false alarm

40
Q

what happens to ACh in frontal cortex in rats performing the attention assay

A

increased ACh