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Bree - Structures > Lecture 43: Muscle tissue with HISTO > Flashcards

Lecture 43: Muscle tissue with HISTO Flashcards

1
Q

functions of muscle tissue

A
  1. movement 2. maintenance of posture 3. joint stabilization 4. heat generation
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2
Q

special functional characteristics of muscle

A
  1. contractility 2. excitability 3. extensibility 4. elastictity
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3
Q

contractility

A

only one action, to shorten. shortening generates pulling force

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4
Q

excitability

A

nerve fibers cause electrical impulse to travel

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5
Q

extensibility

A

stretch with contraction of an opposing muscle

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6
Q

elasticity

A

recoils passively after being stretch

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7
Q

what percent of body weight to skeletal muscle make up

A

40%

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8
Q

what kind of fibers in skeletal muscle

A

multinucleate cells (embryonic cells fuse)

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9
Q

type of contractions in skeletal muscle

A

voluntary

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10
Q

where is cardiac muscle found

A

in the wall of the heart

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11
Q

where is smooth muscle found

A

walls of hollow organs

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12
Q

what do skeletal muscles attach

A

one bone to another and cross at least one moveable join

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13
Q

origin and insertion

A

origin is the less moveable attachment, insertion gets pulled towards the origin (usually one bone moves and the other remains fixed)

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14
Q

convention of location of origin and insertion in muscles of the limb

A

origin lies proximal to insertion

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15
Q

biarticular muscles

A

span two or more joints (also called multijoint) and cause movements at two joints

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16
Q

direct attachment

A

attachment is so short that it appears to attach directly to bone

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17
Q

indirect attachment

A

connective tissue extends well beyond the muscle (more common) ex tendons

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18
Q

can skeletal muscle regenerate

A

minimally

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19
Q

sarcolema

A

plasmalemma or muscle plasma membrane

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20
Q

sarcoplasmic reticulum

A

muscle cell ER

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21
Q

sarcoplasm

A

muscle cell cytoplasm

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22
Q

motor unit

A

1 motor nerve and all the muscle fibers it innervates

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23
Q

muscle cells are called

A

fibers

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24
Q

characteristics of muscle cells

A

multinucleated, peripherally located, surrounded by delicate connective tissue (endomysium)

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25
Q

structure of muscle cell

A

fibers surrounded by endomysium and grouped into bundles called fascicles surrounded by perimysium. bundles of fasicles make up a muscle and are separated by epimysium

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26
Q

muscle fibers are made up of

A

many myofibrils whcih are bundles of myofilaments (thin actin, thick myosin) organized into sarcomeres

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27
Q

what are myofibrils surrounded by

A

sarcoplasmic reticulum and composed of sarcomeres (z to z line)

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28
Q

sarcomere is

A

basic contractile unit of myofiber

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29
Q

subdivisions of sarcomere

A

A band: dark band containing actin and myosin I band: light band with only actin Z line: binds the I band, anchors actin, defines borders of sarcomeres H band: light band, bisects the A band, contains only myosin M line: dark line, bisects H band, anchors myosin filaments

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30
Q

three types of filaments in myofibrils

A
  1. thick (myosin) 2. thin (actin) 3. elastic (titin)
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31
Q

what provides the driving force for movement

A

Myosin II head as ATP drives movement of myosin along actin

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32
Q

what is on the actin filaments that allows it to bind myosin

A

troponin (C, , and T) and tropomyosin which have myosin binding sites

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33
Q

what is alpha actinin

A

it is incoporated into the Z disks and attaches actin to the disks

34
Q

SR is comparable to

A

Smooth ER. tubules surround the myofibrils

35
Q

terminal cisternae

A

cross channels that surround myofibrils. store Ca and release when muscle is stimulated to contract by action potentials.

36
Q

what are t tubules continuous with

A

sarcolemma so whole muscle (including deep parts) contract simultaneously

37
Q

chemical cascade causing muscle contraction

A
  1. neutrotransmitters from motor end plate cause depolarization of sarcolemma (including t tubules) 2. depolarization extends to membranes of SR 3. sudden release of Ca in sarcoplasm 4. Ca binds to troponin C which seperates troponin I from actin and exposes myosin binding site *Contraction begins
38
Q

how does calcium get removed from contracting muscle cell

A

actively pumped back into SR

39
Q

what is the triad in muscle cells

A

t tubule and 2 terminal cisternae

40
Q

physical explanation of muscle contraction

A
  1. myosin head (high energy with ADP and Pi) cross bridge attaches to actin myofilament 2. Myosin head pivots and bends as it bends and pulls on actin filament sliding towards M line (ADP and Pi released to ATP) 3. myosin head gets a new ATP attached and it detaches from actin 4. ATP hydrolyzed to ADP and Pi and this cocks the myosin head back to high energy configuration
41
Q

what do satellite cells do

A

help with muscle generation

42
Q

myasthenia gravis

A

autoimmune disease in which antibodies are produced against acetylcholine receptors so acetylcholine cant bind and there isnt normal muscle interaction. get muscle weakness.

43
Q

cardiac muscle characteristics

A
  1. fibers branch 2. central nuclei (1-2) 3. intercalated disks where cells join 4. no satellite cells 5. t tubules at Z lines 6. cross striations
44
Q

what do bundles in cardiac muscle form

A

thick myocardium

45
Q

cardiac muscle cells

A

single cells (NOT fibers)

46
Q

fiber in cardiac muscle refers to

A

long row of joined cardiac muscle cells (fibers form syncitium)

47
Q

inherent rhythmicity

A

each cell beats seperately without any stimulation

48
Q

diad

A

in cardiac muscle cell, terminal cisternae with t tubule

49
Q

where are t tubules found in cardiac vs skeletal muslce

A

cardiac: level of Z disk skeletal: A-I junction

50
Q

6 major locations of smooth muscle

A
  1. inside the eye 2. walls of vessels 3. respiratory tubes 4. digestive tubes 5. urinary organs 6. reproductive organs
51
Q

characteristics of smooth muscle

A
  1. spindle shaped cells 2. one central nucleus (contour can be irregular during contraction) 3. grouped into sheets that often run perpendicular to each other 4. peristalsis 5. no striations because no sarcomeres 6. contractions are slow, sustained, and resistant to fatigue 7. does not require nervous signal, can be stimulated by stretching or hormones
52
Q

what is analogous to z disks in smooth muscle

A

alpha-actinin rich “cytoplasmic densities” associated with cell membranes

53
Q

how do smooth muscles contract

A
  1. in the absence of t tubules, calcium is brought into cells by endocytic vacuoles (calveolae) 2. calcium binds with calmodulin 3. Ca-calmodulin complex – myosin light chain kinase phosphorylates 4. resulting conformational change exposes actin binding site of myosin and you get contraction
54
Q

where are dense bodies found

A

beneath plasma membrane and in the cytoplasm and contain site of insertion of actin filaments

55
Q

is there myosin filaments in smooth muscle

56
Q

regenerative capacity of the three types of muscle

A
  1. cardiac : virtually no regenerative capacity in adults 2. skeletal: nuclei cannot undergo mitosis but tissue can undergo limited regeneration via satellite cells 3. smooth: has regenerative capacity (ex: enlargement of uterus during pregnancy)
57
Q

actin genes

A

at least four 1. cardiac actin 2. skeletal actin 3. vascular smooth muscle actin 4. visceral smooth muscle actin *changes in genes results in myopathies

58
Q

how can we distinguish myopathies from neuropathies

59
Q
A

cardiac muscle

  1. macula adherens
  2. gap junction
  3. fascia adherens
60
Q
A

cardiac muscle

61
Q
A

cardiac muscle

62
Q
A

dense bodies smooth muscle

63
Q
A

skeletal muscle

64
Q
A

cardiac muscle (high mag)

65
Q
A

smooth muscle (low mag)

66
Q
A

neuromuscular junction

67
Q
A

skeletal muscle

green = A bands

black = I bands

68
Q
A

skeletal muscle with tendon attachment, see bony spicules on either side

69
Q
A

skeletal muscle

70
Q
A

muscle sarcomere

black = z line

grey in middle = m line

71
Q
A

skeletal muscle

green is endomysium

black is perimysium

72
Q
A

green is perimysium, red is muscle fibers

73
Q
A

skeletal muscle with RBCs around

74
Q
A

smooth muscle

75
Q
A

smooth muscle surface calveolae, t tubules

76
Q
A

smooth muscle

77
Q
A

neuromuscular junction

78
Q
A

skeletal muscle triad

79
Q
A

skeletal muscle

SR = sarocplasmic reticulum

M = mitochondria

Bree - Structures (34 decks)

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