LEC43: Muscle Tissue Flashcards Preview

Structures: Part Deux > LEC43: Muscle Tissue > Flashcards

Flashcards in LEC43: Muscle Tissue Deck (111):
1

3 types of muscle tissue

smooth, skeletal, cardiac

2

general functions of muscle tissue

1) movement
2) maintenance of posture
3) joint stabilization
4) heat generation

3

special functional characteristics of muscle

1) contractility
2) excitability
3) extensibility
4) elasticity

4

contractility means

muscle only has 1 action: to shorten
shortening generates pulling force

5

excitability means

muscle can be excited; nerve fibers cause electrical impulse to travel

6

extensibility means

muscle can stretch w/ contraction of an opposing muscle

7

elasticity means

muscle recoils passively after being stretched

8

skeletal muscle location

attach to, move skeleton

9

how much of body weight does skeletal muscle comprise?

40%

10

are skeletal muscle contractions voluntary or involuntary?

voluntary

11

which muscle types are striated?

skeletal, cardiac

12

where is cardiac muscle found?

only in wall of the heart

13

are cardiac muscle contractions voluntary or involuntary?

involuntary

14

where is smooth muscle found?

walls of hollow organs

15

are smooth muscle contractions voluntary or involuntary?

involuntary
..although some voluntary as well

16

what does each skeletal muscle have associated w/ it?

1 nerve, 1 artery, 1 vein, which branch repeatedly

17

what do skeletal muscles connect

1 bone to another

18

what do skeletal muscles span

at least 1 movable joint, but can span 2 or more joints

19

where is skeletal muscle origin/insertion re: movement?

origin: the less movable attachment
insertion: pulled toward the origin

20

do both bones move when skeletal muscle contracts?

no, usually 1 bone moves other remains fixed

21

where is origin re: insertion (proximal, distal)

origin is proximal to insertion

22

what is biarticular muscle?

multijoint muscle, when muscles span 2 or more joints, cause movements at 2 joints

23

what are "fleshy" attachments?

aka direct attachment
attachment so short muscle appears to attach directly to bone

24

what is indirect attachment?

when connective tissue extends well beyond the muscle
eg: tendon

25

what do most skeletal muscles have attached to them?

tendonous attachment - cordlike

26

characteristics of skeletal muscle

1) moves skeleton
2) voluntary/conscious control
3) limited regeneration

27

muscle cell plasma membrane?

sarcolema / plasmalemma

28

muscle cell ER?

sarcoplasmic reticulum

29

muscle cell cytoplasm?

sarcoplasm

30

what comprises a skeletal muscle's motor unit?

1 motor nerve + all the muscle fibers it innervates

31

how many fibers in a muscle cell?

1

32

how is skeletal muscle nucleus?

multinucleated, nuclei are peripherally located, surrounded by endomysium

33

arrangement of skeletal muscle fiber

fiber surrounded by endomysium

34

how are skeletal muscle fibers bundled?

fibers grouped into fasicles; surrounded by perimysium

35

how are several skeletal muscle fasicles grouped?

bundles of fasicles make up a muscle, surrounded by epimysium

36

what are endomysium, perimysium, epimysium made of?

connective tissue

37

what is a muscle cell made of?

many myofibrils

38

what are myofibrils made of?

bundles of myofilaments (thin-actin, thick-myosin), organized into sarcomeres

39

which tissue types are present in a skeletal muscle

all!
- arteries/veins have endothelial cell lining
- nerves have nervous tissue
- CT surrounds muscle cell fibers

40

what is connective tissue function re: skeletal muscle?

necessary for muscle function, continuous with tendons, muscle attachments distributing force of muscle to bone, skin, etc

41

what surrounds myofibril?

sarcoplasmic reticulum

42

what are A and I bands named for?

how they rotate polarized light
I: isotropic: same in all drxns
A: anisotropic: diff in all drxns

43

sarcomere

basic unit of a muscle/myofiber, what allows us to flex
segment between 2 neighboring Z lines

44

subdivisions of sarcomere?

A band, I band, Z line, H band, M line

45

A band?

dark band
actin, myosin filaments

46

I band?

light band
only actin

47

Z line?

bisects I band
anchors actin, defines border of adjacent sarcomeres

48

H band?

light band, bisects A band
only myosin

49

M line?

dark line, bisects H band
anchors myosin

50

what type of filaments make up myofibrils?

1) thick-myosin
2) thin-actin
3) elastic-titin

51

structure of myosin

2 light chains + ATPase domain + actin-binding domain

52

how does myosin filament assemble? what is rod structure?

self-assembles into a-helical tail, large bipolar aggregate or filament

53

what does troponin connect? what is troponin complex made of?

connects to actin a-helices, to tropomyosin between actin filaments

1) calcium binding part
2) inhibitory part-troponin I
3) troponin T, binds to tropomyosin

54

what covers actin's myosin-binding site?

tropomyosin

55

what is driving force for movement in myosin?

myosin II heads, thru ATPase activity move along actin filament

56

what connects actin to Z disc?

a-actinin

57

what connects myosin to Z disc?

titin

58

where is a-actinin?

incorporated into Z disk
attaches actin to the disk

59

what is sarcoplasmic reticulum made of?

smooth ER

60

sarcoplasmic reticulum function?

store Ca++, release it when muscle stimulated to contract

61

what is continuous with sarcolemma? what is the result?

t-tubules
therefore whole muscle contracts simultaneously (including deep parts)

62

what are terminal cisternae

cross-channels in sarcoplasmic reticulum

63

what makes troponins change conformation?

high [Ca++]

64

what binds to troponin in muscle contraction? what is result?

Ca++ binds
Ca++ moves tropomyosin out of the way, bonds to troponin
allows myosin to bind to actin, muscle contraction

65

what happens if [Ca++] is low?

troponin returns to standard conformation
tropomyosin blocks myosin
no muscle contraction

66

role of neurotransmitters in muscle contraction, re: calcium?

1) neurotransmitters from motor end plate cause depolarization of sarcollema, including T-tubules
2) depolarization extends to membranes of sarcoplasmic reticulum
3) Ca++ released into sarcoplasm

67

what happens when Ca++ in sarcoplasm?

binds to Tpn C, separates Tpn I from actin, exposes myosin binding site, contraction cycle begins

68

what surrounds T tubule and skeletal muscle?

2 terminal cisternae

69

what makes up the "triad" of the sarcoplasm? where is it?

2 terminal cisternea + T tubule
at the A-I junction

70

what is the nature of the "triad" in cardiac muscle?

it is a diad

71

motor end-plate function?

motor end plate of neuromuscular junction impinges on muscle fiber

72

what happens to A-I band length when muscle contracts?

it shortens

73

what kind of movement when actin-myosin bind?

RATCHET

74

cause of contraction of muscle fiber?

1) Ca++ influx
2) ATP hydrolyzed to ADP + Pi

75

role of satellite cell in skeletal muscle?

lie within basal lamina
migrate up, make filaments to fill in damaged areas when skeletal muscle damaged

76

what is myasthenia gravis?

autoimmune disease

antibodies against Ach receptor bind to receptor, prevent Ach from binding to it, blocks normal nerve-muscle interaction, no muscle firing

clinically, ppl suffer from progressive muscular weakness

77

how are the fibers in cardiac muscle?

fibers branch

78

position of nucleus in cardiac muscle?

1-2 central nuclei

79

do cardiac muscles have satellite cells?

no

80

what are features within cardiac muscles?

1) intercalated disks
2) T-tubules at Z lines
3) cross-striations

81

how many cells make up a cadiac muscle?

many cells/muscle

82

where do cardiac muscle cells join

interalated disc

83

what is a cardiac muscle "fiber"

long row of joined cardiac muscle cells

84

what is myocardium

thick bundles of cardiac muscle

85

what is inherent rhythmicity?

characteristic of cardiac muscle whereby each muscle cell beats separately, without stimulation

86

syncitium

cardiac muscle cells are interconnected by specialized membranes with gap junctions which are synchronized electrically in an action potential

87

how is terminal cisternae arrangement in cardiac muscle?

diad of terminal cisternae join with T tubule at Z line

88

how does intercalated disc join together cardiac muscle cells?

1) macula adherens
2) gap junction
3) fascia adherens

89

6 major locations of smooth muscle

1) inside eye
2) walls of vessels
3) respiratory tubes
4) digestive tubes
5) urinary organs
6) reproductive organs

90

shape of smooth muscle cells?

spindle-shaped

91

how many nuclei in smooth muscle cell?

1

92

how are smooth muscle cells grouped?

into sheets; often run perpendicular to each other

93

how do smooth muscles move?

slow, sustained contractions that're resistant to fatigue

94

which type of muscles do peristalsis?

smooth muscle

95

what stimulates smooth muscle to contract?

can be stretching, hormones; doesn't have to be nervous signal

96

where is myenteric plexus, what kinds of cells found there?

GI
neuronal ganglion cells

97

what feature of smooth muscle takes in calcium?

surface caveolae, endocytotic vesicles

98

what does calcium bind w/ in smooth muscle?

calmodulin

99

how does smooth muscle contraction cascade work?

Ca-calmodulin complexes > phosphorylation of myosin light chain kinase of myosin rod > conformational change exposing actin binding site of myosin > myosin binds actin > contraction

100

what are dense bodies?

analogous to z-disks, but in smooth muscle

101

where are dense bodies?

in smooth muscle
beneath plasma membrane, in cytoplasm's intercytoplasmic surface

102

what do dense bodies contain?

alpha actinin site of insertion of actin filaments - holds actin in place

103

does smooth muscle have myosin filaments?

yes!

104

what must occur for myosin to be able to bind actin?

myosin light chain kinase phosphorylates light chains; tail extends; forms bipolar myosin filaments, myosin heads can now bind actin

105

which muscle tissue type cannot regenerate in adults?

cardiac muscle

106

can skeletal muscle tissue regenerate?

nuclei cannot undergo mitosis; tissue can undergo limited regeneration

107

what in skeletal muscle allows regeneration?

satellite cells

108

can smooth muscle tissue regenerate?

yes!
i.e. uterus enlarges during pregnancy

109

how many known actin genes?

at least 4
1) cardiac actin
2) skeletal muscle actin
3) vascular smooth muscle actin
4) visceral smooth muscle actin

110

what causes myopathies

changes in actin gene structure

111

how to distinguish myopathy from neuropathy?

histology