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Histology Exam 2 > L14: Muscle Tissue > Flashcards

L14: Muscle Tissue Flashcards

(97 cards)

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1
Q

muscle tissue types

A

skeletal
smooth
cardiac

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2
Q

skeletal muscle characteristics

A
  • multinucleated
  • peripheral nuclei
  • striated
  • each fiber innervated via single motor axon
  • all or none AP
  • myocyte = 50-60 microm
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3
Q

Myofiber types

A

type I
type IIA
type IIB

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4
Q

Myofiber type I

A
  • intense oxidative staining
  • rich in NADH, myoglobin
  • posses many mitochondria
  • primarily uses aerobic metabolism
  • slow contractions
  • dark or red fibers
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5
Q

Myofiber type IIA

A

-intermediate O2 staining
-aerobic and anaerobic
-more rapid than I
resistant to fatigue

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6
Q

Myofiber type IIB

A
  • light staining
  • anaerobic respiration
  • rich in ATPase
  • rapid contraction
  • fatigue quickly
  • white or light fibers
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7
Q

smooth muscle characteristics

A
  • single nucleated cells
  • no sarcomeric arrangement
  • innervated via ANS
  • not all or none
  • cells connect via gap junctions
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8
Q

cardiac muscle characteristics

A
  • single nucleated cells
  • central nuclei
  • cell branching
  • sarcomeric arrangement
  • cells communicate via gap junctions called intercalated discs
  • cells are not directly innervated
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9
Q

hierarchy of skeletal muscle

A 
epimysium
muscle
perimysium
fascicle
endomysium
myofiber
myofibrils
=liner string of sarcomeres
myofilaments
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10
Q

myofilaments

A

thick and thin
or
myosin and actin

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11
Q

epimysium

A

CT covering a muscle

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12
Q

perimysium

A

CT covering a fascicle

consists of fibroblasts and type I collagen

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13
Q

sarcolemma

A

a Myofiber = muscle cell

sarcolemma = muscle cell membrane

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14
Q

endomysium

A

CT covering the Myofiber
also covers sarcolemma

consists of basal lamina and reticular collagen fibers

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15
Q

basal lamina of endomysium

A
  • secreted by muscle cells
  • anchors muscle fibers to each other
  • helps distribute the force of contraction
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16
Q

skeletal muscle fiber structure

A
  • muscle fiber = muscle cell = bundle of fibrils made up of sarcomeres stacked on top of each other
  • each sarcomere consists of Z lines, I bands, A band and H band
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17
Q

sarcomeres are separated from each other by ?

A

transverse discs called Z lines or discs

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18
Q

the A band consists of

A

the length of the myosin filament including the actin cross over section

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19
Q

the length of the A band is equal to ?

A

the length of the bundle of myosin filaments

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20
Q

the I band consists of?

A

the portion of actin filaments not overlapped by myosin at rest

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21
Q

the H band consists of?

A

only thick myosin, the portion not overlapped by actin

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22
Q

changes in band width with contraction

A

the I band shortens
H band may disappear
A band does not change

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23
Q

what happens to sarcomere length during contraction

A

it shortens, the Z discs get closer together

which results in the shortening of the muscle fiber during a contraction

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24
Q

3 dimensional shape of the sarcomere

A

hexagonal shaped

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25
during contraction, forces develop between the actin and myosin filaments, to cause …..
sliding/contraction sliding filament theory
26
when the concentration of ATP decreases, a back up source of energy
hydrolysis of creatine phosphate
27
thick filaments
- myosin | - myosin is a dimeric protein w/ long tails and 2 heads
28
myosin heads
- actin binding region - ATP binding region - light chain binding region
29
myosin light chains
- lost ability to bind Ca - might stabilize heads - required to stabilize myosin II: sites for phosphate binding
30
myosin arrangement in sarcomere
arranged tail to tail in center w/ heads attached to actin results in myosin pulling actin inward from 2 directions
31
F-actin
- polymer of G-actin - consists of 2 polymers in helical arrangement - plus end inserts on Z-discs
32
actin-associated molecules
- troponin | - tropomyosin
33
actin: tropomyosin
- each one sits in groove between 2 actin strands of a filament - each tropomyosin spans 7 actin monomers
34
troponin: actin
complex of 3 molecules 1. troponin I 2. troponin C 3. troponin T
35
troponin I
inhibits binding between actin and myosin
36
troponin C
binds calcium ions
37
troponin T
binds to tropomyosin
38
location of T-tubules in skeletal muscle
located at the A-I junctions
39
location of mitochondria in skeletal muscle fibers
located between myofilaments
40
nebulin
-extends from Z disc to end of actin filament template to regulate length of actin
41
titin
large fibrous protein - spans Z to mid H - connects ends of thick filaments to Z-line - gives myosin elasticity - centers myosin
42
ab-crystallin
heat-shock protein that protects desmin from mechanical stress
43
dystrophin
- links a-actin/desmin complex to cytoplasmic side of sarcolemma - links actin to transmembrane proteins - anchors actin - reinforce sarcolemma
44
dystroglycan complex
links dystrophin intracellular to laminin-2 (extracellular)
45
a-actinin
attaches thin filaments to z-line
46
desmin intermediate filaments
- framework of desmin filaments which surround the Z-line and extend into each sarcomere - link myofibrils laterally to sarcolemma
47
plectin
binds desmin filaments
48
myasthenia gravis
antibodies bind to ACH ligand receptors inhibiting full muscle contractions
49
muscular dystrophy
inherited disease resulting in progressive degeneration of skeletal muscle dystrophin is absent/abnormal in Duchenne's or becker's muscle dystrophy (respectively)
50
satellite cells
- attach to myotubes before basal lamina is laid down - function as stem cells - become mitotic under stress - give rise to myogenic precursor cells
51
myogenic precursor cells
replace damaged muscle by proliferating, fusing and differentiating into skeletal muscle fibers
52
satellite cells are involved in ?
repair, maintenance and regeneration of skeletal muscle tissue
53
mitotic satellite cells
C-Met receptor is binding site for HGF hepatic growth factor
54
satellite cell staining
stain like the nuclei but have a dark band around them use stain CD56 specifically
55
satellite cells can also play a role in ?
hematopoiesis
56
components of the neuromuscular spindle
1. extrafusal fibers 2. intrafusal fibers 3. alpha motor neurons 4. gamma motor neurons 5. primary and secondary afferent fibers
57
fusal = ?
fusiform shape spindle = fusiform shaped structure
58
intrafusal fibers
1. nuclear bag region 2. nuclear bag fibers 3. nuclear chain fibers
59
nuclear bag region
- -intrafusal fibers | - -the sensory region of the neuromuscular spindle
60
what supplies the extrafusal fibers ?
alpha motor neurons extrafusal fibers = skeletal muscle fibers
61
gamma motor neurons
supply the intrafusal fibers
62
afferent fibers are _____ fibers
sensory
63
A1-motor fibers
supply ends of the nuclear bag or chain fibers
64
characteristics of cardiac muscle tissue
1. single central nuclei 2. branching of cells 3. sarcomeric arrangement 4. intercalated discs 5. cells not directly innervated
65
cardia T-tubule system
1. not as extensive as skeletal muscle 2. 1 tubule per 1 cisternae = diad 3. diads at Z-lines
66
purpose of intercalated discs
allow cardiomyocytes to communicate via gap junctions
67
composition of intercalated discs
1. macula adherents = desmosomes 2. fascia adherents 3. gap junctions
68
intercalated disc macula adherents
=desmosomes - -link intermediate filaments of adjoining cardiomyocytes - -transverse component
69
intercalated disc fascia adherents
- -anchor actin filaments of sarcomeres | - -transverse component
70
cardiac macula adherents link ?
desmin (intermediate filaments) to adjoining cells
71
transverse components
hold cardiomyocytes together
72
intercalated discs: longitudinal component
gap junctions
73
what secretes ANP?
cardiac muscle cells in atria
74
ANP
atrial natriuretic peptides
75
function of ANP
1. regulate fluid electrolyte balance | 2. relax vascular smooth muscle to reduce blood vol. and press.
76
storage of ANP
stored in atrial muscle cells as a prohormone in secretory vesicles
77
release of ANP
release is stimulated by atrial stretch---when larger volumes of blood enters atria resulting in cleavage of the prohormone so ANP is released
78
other names for smooth muscle
involuntary visceral
79
smooth muscle cell characteristics
1. single central nuclei 2. no banding pattern 3. innervated via ANS 4. not "all or none" 5. cells connected via gap junctions
80
smooth muscle cells can also be innervated by ?
the enteric system GI system
81
smooth muscle actin and myosin bundles are incorporated into a _______ arrangement, found throughout the ______ except in ______ area.
meshwork arrangement throughout cytoplasm except nuclear area
82
dense bodies are associated with what type of muscle tissue
smooth muscle tissue
83
functions of dense bodies
1. anchor actin to each other and cell membrane | 2. communicate force of contraction to cytoskeleton and cell membrane
84
structure of dense bodies
1. contain a-actinin | 2. interconnected by desmin
85
location of dense bodies
cytoplasm cell membrane of smooth muscle cells
86
smooth muscle cells do not have ?
T-tubule system or extensive SR
87
where does smooth muscle get it's Ca for contraction?
all extracellular
88
purpose of pinocytotic vesicles in smooth muscle
--transport Ca from extra to SR
89
caveolae of smooth muscle
vesicles that appear not sure of their purpose probably involved in trafficking of particles
90
initiation of caveolae formation
caveolin binds to cholesterol in lipid rafts stims caveolae formation
91
smooth muscle lipid rafts
a depression of cell membrane involved in fluid and electrolyte transport
92
lipid raft composition
composed of cholesterol and sphingolipids
93
innervation of smooth muscle cells may either ____ or ______ contraction of muscle cells.
facilitate or inhibit
94
most organs have smooth muscle ….. ?
smooth muscle sheets that are poorly innervated excitation is conducted via many gap junctions
95
adrenergic and muscarinic receptors
linked to G-proteins
96
nicotinic cholinergic receptors
cation channel
97
caveolae start as ….
a lipid raft that is taken inward as a pinocytic vesicle

Histology Exam 2 (8 decks)

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