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WorksheetsNeuro Lec 10-13
Total questions: 22
Worksheet time: 18mins
characteristics of the NMJ:
small size
accessible and relatively simple
synaptic portions of 3 cells: MNs, muscle, Schwann
high concentrations of things that are at low concentrations extrasynaptically
NERVE action potential at the ____ ____ opens voltage-gated ____ ____
Ca2+ influx triggers ____ ____ ____ to presynaptic membrane and Ach ____
(a)
after Ach release, Ach diffuses across the ____ and binds to ____
____ moves in and ____ moves out
this causes postsynaptic membrane ____
(a)
after depol, if the ____ ____ voltage is reached, Na+ channels ____, and muscle AP ensues
(a)
which of the following is false
presyn nerve terminal is filled with synaptic vesicles with ACh
postsynaptic muscle membrane has a high degree of folding
NMJ is covered by terminal Schwann cells
NMJ does not cover terminal
which are true
postsynaptic depol > EPP
EPP > AP threshold triggers opening of voltage-gated Na+ channels
EPP - AP threshold = safety factor (ensures that EPP reliably activates myofibre)
EPP depol myofibre > required for AP threshold
ACh is ____ + ____, catalyzed by ____ (short form)
(a)
choline comes from extracellular fluid (transported by CHT1)
acetyl-CoA comes from mitochondria
true
false
ACh is packed into ____ by VAChT
secretory vesicles
mitochondria
synapses
NMJs
2-10% of ACh vesicles form the ____ ____ pool, which localize at ____ zones and are released upon arrival of ____ ____ and ____ influx
(a)
majority of ACh forms the ____ pool
vesicles recovered by ____ of presynaptic memb, and loaded locally with ____
____ busts ACh into choline and ____
(a)
what is the cytomatrix of the active zone
AZ composed of dense collection of proteins
proteins that tether synaptic vesicles to the presynap memb and mediate vesicular fusion
large proteins at the NMJ AZs
AZs loaded with NMJ synapses
what is the SNARE complex?
release of ACh mediated by vesicular membrane proteins and CAZ proteins
synapsin shuttles ACh vesicles from reserve pool to AZs
ACh vesicle docks at the AZ, undergoes nucleation & zippering
Ca2+ causes fusion of vesicle and presynap memb, exocytosis
positive signal: agrin is released from the ____ ____ and binds to the ____-____ complex
increases the level of ____ (NMJ protein)
(a)
positive signal: neuregulin is released from the ____ ____ and binds ____ receptors.
phosphorylation cascade that results in the phosphorylation of ____, which is a ____ ____
^ this binds to DNA elements in the _-___ to inc trans of NMJ proteins
(a)
positive signals supersede negative signals, resulting in high NMj (AChR)
false
true
negative signal: initiated by ____ release, which triggers ____ influx, turning on the proteins that phosphorylate (inactivate) ____ protein
^that protein usually activates ____ transcription,
thfr less expression of NMJ genes
(a)
the DAPC is:
a mechanical link b/w intraceullar cytoskeleton & extracellular matrix
signal transduction system for cues from the external to reach the internal
comprised of sarcoplasmic, transmemb, and extracellular proteins
located all around the fibre
UAPC vs DAPC
Utrophin is not similar to dystrophin
U is found more along the sarcolemma and D is found more around the NMJ
U is at the crests of the junctional folds, D is at the troughs
the complex itself (aside from U vs D) is identical
testing techniques for dystrophin:
muscle biopsies - plunge lidocaine needle into muscle and suction, take 2 150 mg samples, short recovery,
IF tells us how much of something is expressed and where it is distributed
results between Western blot and IF never conflict each other
Western blot assess how much of something is expressed in the muscle
muscles lacking dystrophin:
have a lot of size variability
go through successive rounds of degeneration/regeneration (almost no mature fibres)
have peripheral nuclei
have thick CT or adipose tissue in the muscle
absence of dystrophin causes:
reduction in the other members of the DAPC
neuromuscular disorders, muscular dystrophies
irregular muscle morphology
musle fibres that are the same size
