The NMJ From a Pharmacological Perspective Flashcards Preview

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Flashcards in The NMJ From a Pharmacological Perspective Deck (60)
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1

what to know?

put out notes packet** read it

2

junctional transmission

cholinergic > bc ACh is neurotransmitter

3

4 important steps in junctional transmission

synthesis of ACh
storage
release
degradation

*every neurotransmitter undergoes this process

4

4 steps in NMJ neurotransmission?

axonal conduction
junctional transmission
ACh signaling
muscle contraction

5

when does junctional transmission occur?

when axonal signal reaches terminal

6

what is activated by ACh?

nAChR

nicotinic acetylcholine receptors

7

choline transporter

membrane channel transports choline into cell
choline is precursor to ACh

cotransport of Na+ and choline into cell

8

choline acetyltransferase

ChAT
enzyme that combines acetyl CoA and choline to form ACh

9

hemicholinium

blocks the choline transporter

**don't need to know - bc its used in labs, not clinically

10

patients with alzheimers?

reduced cerebral production of ChAT
-therefore have less formation of ACh

11

therapy for alzheimers?

to increase ACh levels**
-to make up for loss of low levels

12

ACh vesicular transporter

shuttles ACh into storage vesicle
**requires ATP

1-5K ACh per vesicle

motor nerve terminal may have over 300K vesicles

13

voltage-gated Ca2+ channels

open with depolarization and allow Ca2+ entry into cell

promote vesicle membrane fusion

14

VAMP and SNAPs

vesicular and membrane proteins that initiate vesicle-plasma membrane fusion and release of ACh

15

how many vesicles fuse per AP?

approximately 125 vesicles

16

VAMP

vesicle associated membrane protein

17

SNAP

synaptosome associated proteins

18

what are components of SNARE complex

VAMP-SNAP

19

what does botulinum do?

cleaves the SNARE complex so you can't have vesicle fusion and ACh release

paralyzes muscles**

20

how long for fusion?

matter of milliseconds

21

acetylcholinesterase

AChE
enzyme that cleaves ACh
-into acetate and choline

22

choline transporter

recycles choline back into motor neuron

23

endocytosis?

occurs at nerve terminal to replenish the number of available vesicles

24

two sets of receptors for ACh?

nicotinic and muscarinic

25

nAChR

nicotinic ACh receptor
-also activate by nicotine

ligand gated ion channels (FAST)
sodium to flow into cell
-found pre and post junctionally

causes muscle AP and muscle contraction

26

mAChR

muscarinic ACh receptor
-also activated by muscarine
-found pre and post junctionally

G-protein coupled receptors (SLOW)
NOT located at skeletal NMJ**

27

nAChR distribution

skeletal muscle
cause contraction
respond to ACh and nicotine

28

mAChR distribution

smooth muscle
cause contraction
respond to ACh and muscarine

in cardiac muscle (SA and AV node)
-also on atrium and ventricle
-decreased HR, conduction velocity, contraction

29

subtypes of mAChR

5 in mammals M1-M5

activation is metabotropic

30

metabotropic

causes second messenger pathway