HISTO: Muscle, NMJ Flashcards
(95 cards)
1
Q
what are the types of muscle
A
skeletal, cardial, smooth
2
Q
voluntary stiated muscle
A
skeletal
3
Q
involuntary striated muscle
A
cardiac
4
Q
involuntary nonstriated muscle
A
smooth
5
Q
histological characteristic of skeletal muscle
A
striated, 30-50 nm, peripheral multiple nuclei. syncytium
6
Q
skeletal muscle connective tissues
A
epimysium, perimysium, endomysium
7
Q
the repeating structural unit of skeletal muscle that gives the striated appearance
A
sarcomere
8
Q
what does the sarcomere consist of
A
z bands
i bands
a bands
m bands
h bands
9
Q
myosin containing thick filaments
A
a bands
10
Q
actin containing thin filaments
A
i bands
11
Q
a-actinin crosslinking thin filaments
A
z bands
12
Q
what is myosin composed of
A
rod and two heads
13
Q
m- bands contain
A
myomisium, m protein and obscurin
14
Q
main accessory protein of the skeletal and cardiac thick filaments
A
Myosin Binding Protein C (MyBP-C)
15
Q
myosin characteristic
A
bipolar structure - has bare zone
16
Q
what part os the thick filament interacts with actin
A
the myosin heads
17
Q
able to bind at its amino terminal to either the myosin head or the adjacent actin thin filament
A
MyBP-C
18
Q
thin filament characteristic
A
double helical actin arrangement + Ca2 regulatory proteins - tropomyosin and troponin
19
Q
Ca2+ regulatory proteins
A
tropomysoin and troponin
20
Q
troponin subunits
A
TnT - tropomysoin binding
TnC - calcium binding
TnI - inhibitory
21
Q
extra proteins in sarcomere
A
titin - allows elasticity
tropomodulin - stabilize
nebulin
dystrohpin
desmin
22
Q
associated with mutations affecting the expression of the dystrophin protein
A
Muscular dystrophies: DMD and BMD
23
Q
associated with mutations on the short arm of the X chromosome for the 4 different sarcoglycan membrane proteins
A
Limb girdle LGMD
24
Q
caused by a mutation in the gene encoding the alpha-2 chain of muscular laminin
A
Congenital msucular dystrophy
25
due to a dominate mutation in desmin
desmin-related myopathy
26
what occurs in desmin myopathys
The desmin molecules form aggregates rather than the desmin intermediate filaments. This results in disorganized myofilaments, myofibrils, and disorganized skeletal muscles
27
tubular invaginations of sarcolemma into cytoplasm at the AI junction of the sarcomere
t-tubules
28
sarcoplasmic reticulum function
specialized smooth endoplasmic reticulum able to store, release, and sequester calcium
29
what are triads
specialized regions in which a central t-tubule is flanked by two terminal cisterna sacs of the SR
30
what does the Terminal cisterna of SR contain
calsequestrin
31
what is SERCA short for
Smooth Endoplasmic Reticulum Calcium ATPase (SERCA)
32
SERCA function
pumps calcium from the cytoplasm back into sarcoplasmic reticulum and back to the terminal cisterna
33
what happens when sufficient calcium is removed from the cytoplasm
the contraction of the skeletal muscle will stop until the next cycle of depolarization of the sarcolemma occurs
34
Regulation of contraction is controlled by the _____ concentration in the cytoplasm
calcium
35
calcium regulation of contraction involves:
excitation contraction coupling
steric blocking mechanism of calcium regulation, sliding filament mechanism of contraction
36
which mechanism couples the nerve stimulation at the muscle cell surface to the release of calcium into the cytoplasm
Excitation Contraction Coupling Mechanism
37
which mechanism initiates contraction upon release of high levels of calcium
steric blocking
38
which mechanism is in which thick and thin filaments slide past each other to produce shortening of the sarcomere
sliding filament
39
excitation contraction couplings involves
DHSRs - depolarization sensitive channels activated when plasma mebrane depolarizes
40
conformation changes of DSHRs affect
gated Ca2 release channels RyR1- Ca binds to actin - initiating contraction!!
41
In the absence of calcium the______complex blocks the binding site for myosin on actin
troponin-tropomyosin
42
result of sliding filaments
shortening of sarcomere
43
stage 1 of myosin contractile cycle
myosin bound to thin filament, no atp
44
stage 2 of myosin contractile cycle
atp binds to myosin causing head to detach from thin filament
45
stage 3 of myosin contractile cycle
atp on head is hydrolyzed to adp +pi - provides energy for shape of myosin head
46
stage 4 of myosin contractile cycle
reattachment of head to new actin - weak bindingq
47
stage 5,6 of myosin contractile cycle
pi is released. strong binding producing power stroke that moves thin filament inwards to bare zone - adp release and cycle repeats
48
relaxation conditions
atp present but no Ca2+
49
contraction conditions
both atp and Ca2+ present
50
rigor conditions
no atp present - rigor mortis
51
fiber types in skeletal muscle
fast white glyocolytic
fast oxidative gycolitic
slow oxidative
52
Type IIb (Fast White Fibers)
- largest in size; stain for fast myosin isozyme and can contract rapidly
- are easily fatigued
fast glycolitic fibers
53
Type IIa (Intermediate fibers)
–Intermediate in
diameter; stain for fast myosin isozyme and also allow fast contraction
- less easily fatigued than white fibers
fast oxidative glycolitic fibers
54
Type I (Slow Red
Fibers) –Smallest in diameter; stain for slow myosin isozyme and contract more slowly
- least fatiguable of fibers
- have the greatest number of mitochondria
slow oxidative fibers - dark stain
55
skeletal muscle fiber types are stained for
mitochondria
dark - slow
light - fast
56
is associated with a loss in skeletal muscle mass, muscle strength and force, and power
sarcopenia
57
major loss fiber in sarcopenia
type II with satellite cells
58
Site of innervation of skeletal muscle fibers by motor neurons
NMJ
59
Free nerve endings lie in depressions on skeletal muscle surface known as
motor end plates
60
The skeletal muscle cell surface is highly folded to form
junctional folds
61
ach in synaptic vesicles bind to ___ at NMJ
nicotinic acetylcholine receptor (ach receptor) in sarcolemma
62
ach is broken down by ___ in basal lamina
cholinesterase
63
condition where auto-immune antibodies block, alter or destroy the acetylcholine receptors thus blocking stimulation of the skeletal muscle
Myasthenia gravis
64
Associated with small cell carcinoma of the lung involves antibodies against many of the presynaptic membrane proteins
lambert eaton myasthenic syndrome
65
toxins at nmj
botulinum, tetanus, snake
66
Due to a progressive death of neurons in the spinal cord and brain that innervate the voluntary muscles. No cure.
Amyotrophic Lateral Sclerosis (ALS)
67
characteristic of Myasthenia gravis
ptosis eyes, double vision, weakness, impaired swallowing, chewing, speaking
68
what does botulimun toxin affect
Acidification of the endocytosed vesicle results in the translocation of the toxin into the cytoplasm where it cleaves synaptobrevin (VAMP)
69
what does tetanus toxin affect
transported to the spinal cord where it translocates to the pre- synaptic terminal of inhibitory neurons
70
act as sensory detectors of stretch in the skeletal muscles
intrafusal fibers of muscle spindle
71
what sensory nerve wraps intrafusal fiber
type 1a
72
what sensory nerve monitors stetch in tendon
type 1b
73
cardiac muscle histological characteristics
striated
intermediate diameter fiber
single nuclei conterally
intercalated discs!
large mitochondria
gap junctions
74
intercalated disks are part of which muscle type
cardiac muscle
75
intercellular junctions at cardiac muscle: 3
fascia adherens, desmosomes, gap junctions
76
in what type of muscle is mitochondria large
cardiac muscle - energy requirement
77
where are Diads found
ventricular fiber of cardiac muscle
78
diads composition
Ca2+ channels in T-tubule and 2 Ca channels in 1 flattened sac of SR terminal cisterna
79
true or false:T-tubules are typically found in atrial muscle
false
80
the main sites of calcium release for contraction in the ventricle of cardiac muscle
diads
81
cardiac muscle Ca2+ additional release sites
-junctional contacts
-corbular sarcoplasmic reticulum
82
SERCA2a isoform function
present in cardiac muscle and acts to pump calcium back into the SR between contractions
83
depending on its phosphorylation state can either inhibit or open the SERCA pump channels
phospholamban
84
what fibers bring impulse (depolarization) for contraction into ventricle
purkinje fibers
85
excitation contraction coupling in atria is by
calcium release and ryanodine 2 receptor calcium channels in saccules of corbular SR
86
smooth muscle histologic characteristics
nonstriated
spindle shaped
small fibers
single central nuclei
gap junctions electrically
Membrane attachment plaques & cytoplasmic dense bodies
87
Membrane attachment plaques & cytoplasmic dense bodies containing
alpha actinin
88
thick and thin filament structure in smooth muscle:
side polar structure
89
which tubules are absent in smooth muscle
t-tubules because small diameter of cells
90
Regulation of contraction in smooth muscle involves
Ca2 binding - calmodulin to mysoin and phosphorylation of myosin
not tropomyosin-troponin complex
91
factors that can cause contraction or relaxation of smooth muscle
mechanical stimuli - stretching
electrical depolarization - neu
binding of hormoones
92
Growth of skeletal muscle is primarily by
hypertrophy
93
Some regeneration or repair can take place in muscles by:
satellite cells
94
which muscle can divide and regenerate
smooth muscle hypertrophy in myometrium in pegnancy
95
can cardiac muscle renegerate
can not - limited
