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Histology Exam 2 > L14: Muscle Tissue > Flashcards

L14: Muscle Tissue Flashcards

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
Q

during contraction, forces develop between the actin and myosin filaments, to cause …..

A

sliding/contraction

sliding filament theory

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26
Q

when the concentration of ATP decreases, a back up source of energy

A

hydrolysis of creatine phosphate

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27
Q

thick filaments

A
  • myosin

- myosin is a dimeric protein w/ long tails and 2 heads

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28
Q

myosin heads

A
  • actin binding region
  • ATP binding region
  • light chain binding region
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29
Q

myosin light chains

A
  • lost ability to bind Ca
  • might stabilize heads
  • required to stabilize myosin II: sites for phosphate binding
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30
Q

myosin arrangement in sarcomere

A

arranged tail to tail in center w/ heads attached to actin

results in myosin pulling actin inward from 2 directions

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31
Q

F-actin

A
  • polymer of G-actin
  • consists of 2 polymers in helical arrangement
  • plus end inserts on Z-discs
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32
Q

actin-associated molecules

A
  • troponin

- tropomyosin

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33
Q

actin: tropomyosin

A
  • each one sits in groove between 2 actin strands of a filament
  • each tropomyosin spans 7 actin monomers
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34
Q

troponin: actin

A

complex of 3 molecules

  1. troponin I
  2. troponin C
  3. troponin T
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35
Q

troponin I

A

inhibits binding between actin and myosin

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36
Q

troponin C

A

binds calcium ions

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37
Q

troponin T

A

binds to tropomyosin

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38
Q

location of T-tubules in skeletal muscle

A

located at the A-I junctions

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39
Q

location of mitochondria in skeletal muscle fibers

A

located between myofilaments

40
Q

nebulin

A

-extends from Z disc to end of actin filament

template to regulate length of actin

41
Q

titin

A

large fibrous protein

  • spans Z to mid H
  • connects ends of thick filaments to Z-line
  • gives myosin elasticity
  • centers myosin
42
Q

ab-crystallin

A

heat-shock protein that protects desmin from mechanical stress

43
Q

dystrophin

A
  • links a-actin/desmin complex to cytoplasmic side of sarcolemma
  • links actin to transmembrane proteins
  • anchors actin
  • reinforce sarcolemma
44
Q

dystroglycan complex

A

links dystrophin intracellular to laminin-2 (extracellular)

45
Q

a-actinin

A

attaches thin filaments to z-line

46
Q

desmin intermediate filaments

A
  • framework of desmin filaments which surround the Z-line and extend into each sarcomere
  • link myofibrils laterally to sarcolemma
47
Q

plectin

A

binds desmin filaments

48
Q

myasthenia gravis

A

antibodies bind to ACH ligand receptors inhibiting full muscle contractions

49
Q

muscular dystrophy

A

inherited disease resulting in progressive degeneration of skeletal muscle

dystrophin is absent/abnormal in Duchenne’s or becker’s muscle dystrophy (respectively)

50
Q

satellite cells

A
  • attach to myotubes before basal lamina is laid down
  • function as stem cells
  • become mitotic under stress
  • give rise to myogenic precursor cells
51
Q

myogenic precursor cells

A

replace damaged muscle by proliferating, fusing and differentiating into skeletal muscle fibers

52
Q

satellite cells are involved in ?

A

repair, maintenance and regeneration of skeletal muscle tissue

53
Q

mitotic satellite cells

A

C-Met receptor is binding site for HGF

hepatic growth factor

54
Q

satellite cell staining

A

stain like the nuclei but have a dark band around them

use stain CD56 specifically

55
Q

satellite cells can also play a role in ?

A

hematopoiesis

56
Q

components of the neuromuscular spindle

A
  1. extrafusal fibers
  2. intrafusal fibers
  3. alpha motor neurons
  4. gamma motor neurons
  5. primary and secondary afferent fibers
57
Q

fusal = ?

A

fusiform shape

spindle = fusiform shaped structure

58
Q

intrafusal fibers

A
  1. nuclear bag region
  2. nuclear bag fibers
  3. nuclear chain fibers
59
Q

nuclear bag region

A
  • -intrafusal fibers

- -the sensory region of the neuromuscular spindle

60
Q

what supplies the extrafusal fibers ?

A

alpha motor neurons

extrafusal fibers = skeletal muscle fibers

61
Q

gamma motor neurons

A

supply the intrafusal fibers

62
Q

afferent fibers are _____ fibers

A

sensory

63
Q

A1-motor fibers

A

supply ends of the nuclear bag or chain fibers

64
Q

characteristics of cardiac muscle tissue

A
  1. single central nuclei
  2. branching of cells
  3. sarcomeric arrangement
  4. intercalated discs
  5. cells not directly innervated
65
Q

cardia T-tubule system

A
  1. not as extensive as skeletal muscle
  2. 1 tubule per 1 cisternae = diad
  3. diads at Z-lines
66
Q

purpose of intercalated discs

A

allow cardiomyocytes to communicate via gap junctions

67
Q

composition of intercalated discs

A
  1. macula adherents = desmosomes
  2. fascia adherents
  3. gap junctions
68
Q

intercalated disc macula adherents

A

=desmosomes

  • -link intermediate filaments of adjoining cardiomyocytes
  • -transverse component
69
Q

intercalated disc fascia adherents

A
  • -anchor actin filaments of sarcomeres

- -transverse component

70
Q

cardiac macula adherents link ?

A

desmin (intermediate filaments) to adjoining cells

71
Q

transverse components

A

hold cardiomyocytes together

72
Q

intercalated discs: longitudinal component

A

gap junctions

73
Q

what secretes ANP?

A

cardiac muscle cells in atria

74
Q

ANP

A

atrial natriuretic peptides

75
Q

function of ANP

A
  1. regulate fluid electrolyte balance

2. relax vascular smooth muscle to reduce blood vol. and press.

76
Q

storage of ANP

A

stored in atrial muscle cells as a prohormone in secretory vesicles

77
Q

release of ANP

A

release is stimulated by atrial stretch—when larger volumes of blood enters atria

resulting in cleavage of the prohormone so ANP is released

78
Q

other names for smooth muscle

A

involuntary

visceral

79
Q

smooth muscle cell characteristics

A
  1. single central nuclei
  2. no banding pattern
  3. innervated via ANS
  4. not “all or none”
  5. cells connected via gap junctions
80
Q

smooth muscle cells can also be innervated by ?

A

the enteric system

GI system

81
Q

smooth muscle actin and myosin bundles are incorporated into a _______ arrangement, found throughout the ______ except in ______ area.

A

meshwork arrangement

throughout cytoplasm

except nuclear area

82
Q

dense bodies are associated with what type of muscle tissue

A

smooth muscle tissue

83
Q

functions of dense bodies

A
  1. anchor actin to each other and cell membrane

2. communicate force of contraction to cytoskeleton and cell membrane

84
Q

structure of dense bodies

A
  1. contain a-actinin

2. interconnected by desmin

85
Q

location of dense bodies

A

cytoplasm
cell membrane

of smooth muscle cells

86
Q

smooth muscle cells do not have ?

A

T-tubule system
or
extensive SR

87
Q

where does smooth muscle get it’s Ca for contraction?

A

all extracellular

88
Q

purpose of pinocytotic vesicles in smooth muscle

A

–transport Ca from extra to SR

89
Q

caveolae of smooth muscle

A

vesicles that appear

not sure of their purpose

probably involved in trafficking of particles

90
Q

initiation of caveolae formation

A

caveolin binds to cholesterol in lipid rafts

stims caveolae formation

91
Q

smooth muscle lipid rafts

A

a depression of cell membrane involved in fluid and electrolyte transport

92
Q

lipid raft composition

A

composed of cholesterol and sphingolipids

93
Q

innervation of smooth muscle cells may either ____ or ______ contraction of muscle cells.

A

facilitate or inhibit

94
Q

most organs have smooth muscle ….. ?

A

smooth muscle sheets that are poorly innervated

excitation is conducted via many gap junctions

95
Q

adrenergic and muscarinic receptors

A

linked to G-proteins

96
Q

nicotinic cholinergic receptors

A

cation channel

97
Q

caveolae start as ….

A

a lipid raft that is taken inward as a pinocytic vesicle

Histology Exam 2 (8 decks)

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