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1

2 types of muscle cells can exist outside of "muscle tissue," what are they, what germ layers are they derived from, and where are they found?

-myofibroblasts, from mesenchyme, ct
-myoepithelial cells, from ectoderm, epithelia

2

which free muscle cells come from the mesoderm and which come from the ectoderm?

mesoderm - myofribroblasts
ectoderm - myoepithelial cells

3

RBCs dispersed in connective tissue probably indicates...

a wound

4

myosin expressed in connective tissue =

a myofibroblast

5

myosin expressed in epithelial tissue =

a myoepithelial cell

6

myofibroblast

myosin expressed in connective tissue

7

myosin expressed in epithelial tissue

myoepithelial cell

8

where might you expect to find myoepithelial cells?

basally in glandular epithelium to help squeeze out secretions

9

myofibroblasts are derived from __

mesenchyme

10

myoepithelial cells are derived from __

ectoderm

11

visceral smooth muscle =

smooth muscle surrounding visceral organs

12

appearance of a myofibroblast LM

fusiform, basophilic cytoplasm

13

this cell has ~shape of a fibroblast when relaxed but contracts into a corkscrew shape

smooth muscle cell

14

actin, dense bodies, and intermediate filaments are components of what cell type?

smooth muscle cell

15

what are the intermediate filaments in smooth muscle?

arteries / veins - vimentin
most other places - desmin

16

how are dense bodies attached to one another

intermediate filaments (to transmit force)
arteries / veins - vimentin
most other places - desmin

17

greek root for muscle
latin root for muscle

sarco
myo

18

sarcolemma

muscle plasma membrane

19

muscle plasma membrane

sarcolemma

20

pinocytotic vesicles in smooth muscle plasma membrane

caveoli
-regulate intracellular Ca++ concentrations
-slow regulation but ok because smooth muscle acts slowly / gradually

21

T/F smooth muscle has no sarcoplasmic reticulum

false
does have sarcoplasmic reticulum for Ca++ sequestration, but caveoli are the primary means of regulating intracellular Ca++ concentrations...

22

sarcomeres are associated into __

myofibrils

23

myofiber

membrane bound element of muscle
-syncytium in skeletal muscle
-myocite in smooth and cardiac muscle

24

myocite

individual muscle cells in cardiac and smooth muscle

25

T/F myocites exist in skeletal muscle

false?
no myocites, just syncyctiums of myofibers?

26

how to tell smooth muscle from skeletal muscle

smooth - centra nucleus, no striations
skeletal - peripheral multinucleated, striations

27

T/F striations are parallel to sarcomere arrangement

false
striations = alternating A bans and I bands

28

T/F striations are perpendicular to sarcomere arrangement

true
striations = alternating A bans and I bands

29

how does weight lifting change skeletal muscle?

increased diameter of fibers

30

T/F weight lifting increases the number of myofibers

false
increases diameter of myofibers

31

T/F a skeletal muscle fiber is typically as long as the whole muscle

true

32

dark band in striation

A band

33

light band in striation

I band

34

dark band in center of light band in striation

Z line

35

light band in center of dark band in striation

H zone

36

dark band in center of light band in center of dark band in striation

M line

37

how many myofibrils in a membrane bound myofiber

hundreds

38

T/F from largest to smallest, muscle elements include:
myofiber
myofibril
sarcomere
myofilaments

true

39

3 connective tissue investments surrounding muscle tissue

endomysium - surrounds myofiber
perimysium - surrounds fascicles
epimyseium - surrounds multiple fasicles (muscle as a whole), connects muscle to tendon

40

T/F blood vessels can be found in endo, peri, and epimysium

true?
smaller in endomysium
larger in perimysium
any blood vessels in epimysium?

41

T/F adipose and nervous tissue are possible in perimysium

true

42

how does skeletal muscle tissue arise?

somite
myotome
myoblasts (muscle progenitor cells)
myocites
functional syncytium
myofibrils

43

satellite cells in muscle

within the external lamina outside sarcolemma
-presumably capable of regenerating myofibers in case of damage

44

within the external lamina outside sarcolemma
-presumably capable of regenerating myofibers in case of damage

satellite cells in muscle

45

T/F endomysium contains external lamina

true
external lamina is outside all plasmalemma

46

external lamina of muscle

surrounds all plasmalemma
-yes within endomysium
-yes within perimysium
-yes within epimysium
surround ALL PLASMALEMMA

47

T/F external lamina = external membrane

true
same thing

48

this is ~ the basement membrane of muscle

external lamina

49

what are the components of the external lamina?

same as basement membrane
-lamina lucida
-lamina densa
-lamina reticularis (type IV collagen)

50

striated muscle encompasses...

skeletal muscle
cardiac muscle

51

what muscle types are not striated?

smooth muscle

52

a myocyte that persists outside the sarcolemma of a muscle fiber, but inside the external membrane

satellite cell

53

alpha-actinin

protein of Z line holding actin

54

protein of Z-line holding actin

alpha-actinin

55

myomesin and C-protein

form M line holding myosin together

56

materials that form M line holding myosin together

myomesin and C-protein

57

myomesin

forms M line with C-protein to hold myosin together

58

C-protein

forms M line with myomesin to hold myosin together

59

nebulin and titin

hold myosin to Z-line

60

materials that hold myosin to Z-line

nebulin and titin

61

nebulin

with titin holds myosin to Z line

62

titin

with nebulin anchors myosin to Z line

63

costamere

where myofibrils are bound to plasmalemma by intermediate filaments and dystrophin

64

where myofibrils are bound to plasmalemma by intermediate filaments and dystrophin

costameres

65

dystrophin

protein that binds myofibrils to plasmalemma with intermediate filaments at costameres

66

protein that binds myofibrils to plasmalemma with intermediate filaments at costameres

dystrophin

67

how are sarcomeres anchored within myofiber?

anchored to plasmalemma at costameres by intermediate filaments and dystrophin

68

types of skeletal muscle

type I - red (slower, non-fatigue, aerobic)
type IIa - intermediate
type IIb - white (faster, fatigue, anaerobic)

69

T/F muscle fibers can change type on spectrum from red to white in response to use

true

70

connective tissue connected to external membrane of muscle

endomysium

71

connective tissue fascia that binds the anatomical form of the muscle to the surrounding tissues

epimysium

72

order skeletal, cardiac, and smooth muscle according to size

skeletal (largest)
cardiac
smooth (smallest)

73

T/F cardiac myocytes are much smaller than skeletal muscle fibers but larger than smooth muscle myocites

true

74

how many nuclei in a cardiac myocite

1-2

75

sarcoplasmic cone

lighter area where myofibers bend around centrally located nucleus in cardiac myocyte

76

T/F like skeletal muscle, cardiac myocyte nuclei are squished to perifery

false
sarcoplasmic cone = lighter area where myofibers bend around centrally located nucleus in cardiac myocyte

77

adjacent myocites are connected electrically through ... and bound physically through ...

gap junctions
fascia adherens

78

fascia adherens in cardiac muscle tissue

binds cardiac myocites together physically
(intercalated disk)

79

modified myocites for conducton of electrical signals through heart

purkinje fibers
-fewer myofilaments

80

these cardiac myocytes will have fewer myofilaments than others

purkinje fibers
-specialized for conduciotn

81

intercalated disk

fascia adherens
-connect cytoskeletal actin of joined cells
-cadherins + actin

82

the intercalatd disk (fascia adherens) in cardiac muscle is most similar to what structure in epithelial tissue?

zonula adherens (adherens junction)
-connect cytoskeletal actin of joined cells
-cadherins + actin

83

T/F desmosomes correspond to zonula adherens

false
-desmosomes correspond to macula adherens (spot weld) junctions - cadherins + keratin intermediate filaments
-zonula adherens = cadherins + actin

84

synonym for desmosome

macula adherens (spot weld) junctions
-cadherins + keratin intermediate filaments

85

evolutionarily oldest form of muscle

smooth muscle

86

dense bodies / dense plaques

anchoring proteins for myofilaments in smooth muscles (homologues of z-lines)
-connected to each other via intermediate filaments

87

involuntary muscle includes...

smooth muscle
cardiac muscle

88

2 classes of smooth muscle

unitary - acts as one mechanical unit
multiunit - ~1:1 axon:cell ratio for finer control

89

will the iris have unitary or multiunit smooth muscle?

multiunit
~1:1 axon:cell ratio for finer control

90

T/F smooth muscle cells in the uterine myometrium are hormonally responsive and grow up to 200 microns in length during pregnancy

true

91

how are smooth muscle cells in the uterine myometrium hormonally responsive?

grow up to 200 microns in length during pregnancy

92

neuromuscular junction

specialized structure joining nerve axon with muscle
(most specialized in skeletal muscle, but present in rudimentary form in smooth muscle too)

93

specialized structure joining nerve axon with muscle
(most specialized in skeletal muscle, but present in rudimentary form in smooth muscle too)

neuromuscular junction

94

junctional folds

local invaginations of the sarcolemma underneath the point of contact with the axon, designed to increase surface area and number of ACh receptors

95

local invaginations of the sarcolemma underneath the point of contact with the axon, designed to increase surface area and number of ACh receptors

junctional folds

96

muscle spindles

-sensory structures in muscle to sense position and stretch-state
-composed of modified muscle fibers (bag and chain fibers) with sensory neurons that sense position and stretch and gamma motor neurons that alter sensitivity
-encapsulated by its own perimysium

97

sensory structures in muscle to sense position and stretch-state

muscle spindles

98

composed of modified muscle fibers (bag and chain fibers) with sensory neurons that sense position and stretch and gamma motor neurons that alter sensitivity

muscle spindle

99

bag and chain fibers

modified muscle fibers in a muscle spindle that includes sensory neurons to sense position and stretch and gamma motor neurons to alter sensitivity

100

modified muscle fibers in a muscle spindle that includes sensory neurons to sense position and stretch and gamma motor neurons to alter sensitivity

bag and chain fibers

101

gamma motor neuron

motor neuron specific to muscle spindle to modify sensitivity of sensory neurons to position and stretch

102

motor neuron specific to muscle spindle to modify sensitivity of sensory neurons to position and stretch

gamma motor neurons

103

golgi tendon organ

like a muscle spindle with specialized muscle fibers and sensory and motor neurons
-positioned between muscle fibers and connecting tendon
-primarily associated with reflexive responses of the muscles

104

positioned between muscle fiber and tendon,
~like a muscle spindle with specialized muscle fibers and sensory and motor neurons

golgi tendon organ

105

primarily associated with reflexive response of muscles

golgi tendon organ

106

muscle spindle is homologous in structure and function to...

golgi tendon organ

107

golgi gendon organ is homologous in structure and function to...

muscle spindle

108

difference between muscle spindle and goligi tendon organ?

-muscle spindle: specialized muscle fibers and nerves to sense position and stretch, in muscle itself
-golgi tendon organ: specialized muscle fibers and nerves to sense position and stretch, between muscle and tendon, mostly for reflexive response of muscle

109

T/F unitary and multiunit smooth muscle is on somewhat of a spectrum depending on nerve:myocyte ratio

true

110

3 subclasses of muscle

-striated (I,IIA,IIB skeletal; standard, endocrine, conducting cardiac)
-smooth (unitary, multiunit)
single cell (myofibroblast, myoepithelial)

111

how do you tell unitary from multiunit smooth muscle apart on H&E?

very difficult, need to know anatomy
-perhaps with special nerve stain

112

intracellular actin of neighboring cells meet at ...

zonula adherens
(adherens junctions)
catenin + actin

113

how is actin anchored to dense bodies in smooth muscle?

f-actin tethered to dense bodies by a-actin

114

a-actin

tethers f-actin to dense bodies in smooth muscle

115

T/F there exist smooth muscles that are under voluntary control

false
smooth muscle Never under voluntary control (by definition, as far as we know..., in humans)

116

between unitary and multiunit smooth muscle, which would you call myogenic and which would you call neurogenic?

unitary - myogenic (single axon many gap juncitons)
multiunit - neurogenic (axon:myocite ~1:1)

117

iris, erector pilli, large blood vessels, and small airways of the lung contain unitary or multiunit smooth muscle?

multiunit
fine control

118

do caveoli appear on P or E face in freeze fracture?

both
endocytosing vesicles will appear similarly on both E and P face

119

T/F caveoli can be associated with cardiac muscle

false
smooth muscle only
-Ca++ release from SR in cardiac initiated by action potential, sarcolemma, T-tubules, sarcoplasmic reticulum
-Ca++ release from SR in sooth muscle initiated by caveoli

120

T/F caveoli can be associated with skeletal muscle

false
smooth muscle only
-Ca++ release from SR in skeletal initiated by action potential, sarcolemma, T-tubules, sarcoplasmic reticulum
-Ca++ release from SR in sooth muscle initiated by caveoli

121

T/F caveoli can be associated with smooth muscle

true
smooth muscle only
-Ca++ release from SER in sooth muscle initiated by caveoli

122

dyad

where t-tubule meets a terminal cisterna of SR in cardiac myocites @ Z-lines

123

where t-tubule meets a terminal cisterna of SR in cardiac myocites @ Z-lines

dyad

124

how many feet in a dyad

2
1 terminal cisterna of SR
1 t-tubule

125

where does a dyad rest on a cardiac myocite?

at Z-lines

126

the specific name for the zonula adherens in cardiac muscle

fascia adherens

127

T/F intercalated disks are composed of gap junctions

false
yes, there are gap junctions there, but gap junctions also appear laterally; the intercalated disk is due to the fascia adherens (cadherins + actin)

128

T/F the t-tubule contains extracellular space

true

129

triad

where t-tubule meets 2 terminal cisternae of sarcoplasmic reticulum
-located where I band meets A band (right where it needs to deliver calcium)

130

where t-tubule meets 2 terminal cisternae of sarcoplasmic reticulum

triad
-located where I band meets A band (right where it needs to deliver calcium)

131

located where I band meets A band (right where it needs to deliver calcium)

triad
where t-tubule meets 2 terminal cisternae of sarcoplasmic reticulum

132

T/F cardiac myocytes are usually binucleated

false
binucleaton possible, but usually mononucleated

133

cytoplasmic space devoid of myofibrils but full of organelles in cardiac myocyte

sarcoplasmic cone
-caused because myofibrils spanning entire cardiac myocite must get around nucleus

134

caused because myofibrils spanning entire cardiac myocite must get around nucleus

sarcoplasmic cone
cytoplasmic space devoid of myofibrils but full of organelles

135

T/F actin filaments span the entire length of a cardiac myosite

false
myofibrils (composed of multiple sarcomeres) span the entire length of cardiac myocyte