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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
structure of muscle cell
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
26
muscle fibers are made up of
many myofibrils whcih are bundles of myofilaments (thin actin, thick myosin) organized into sarcomeres
27
what are myofibrils surrounded by
sarcoplasmic reticulum and composed of sarcomeres (z to z line)
28
sarcomere is
basic contractile unit of myofiber
29
subdivisions of sarcomere
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
30
three types of filaments in myofibrils
1. thick (myosin) 2. thin (actin) 3. elastic (titin)
31
what provides the driving force for movement
Myosin II head as ATP drives movement of myosin along actin
32
what is on the actin filaments that allows it to bind myosin
troponin (C, , and T) and tropomyosin which have myosin binding sites
33
what is alpha actinin
it is incoporated into the Z disks and attaches actin to the disks
34
SR is comparable to
Smooth ER. tubules surround the myofibrils
35
terminal cisternae
cross channels that surround myofibrils. store Ca and release when muscle is stimulated to contract by action potentials.
36
what are t tubules continuous with
sarcolemma so whole muscle (including deep parts) contract simultaneously
37
chemical cascade causing muscle contraction
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
how does calcium get removed from contracting muscle cell
actively pumped back into SR
39
what is the triad in muscle cells
t tubule and 2 terminal cisternae
40
physical explanation of muscle contraction
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
what do satellite cells do
help with muscle generation
42
myasthenia gravis
autoimmune disease in which antibodies are produced against acetylcholine receptors so acetylcholine cant bind and there isnt normal muscle interaction. get muscle weakness.
43
cardiac muscle characteristics
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
what do bundles in cardiac muscle form
thick myocardium
45
cardiac muscle cells
single cells (NOT fibers)
46
fiber in cardiac muscle refers to
long row of joined cardiac muscle cells (fibers form syncitium)
47
inherent rhythmicity
each cell beats seperately without any stimulation
48
diad
in cardiac muscle cell, terminal cisternae with t tubule
49
where are t tubules found in cardiac vs skeletal muslce
cardiac: level of Z disk skeletal: A-I junction
50
6 major locations of smooth muscle
1. inside the eye 2. walls of vessels 3. respiratory tubes 4. digestive tubes 5. urinary organs 6. reproductive organs
51
characteristics of smooth muscle
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
what is analogous to z disks in smooth muscle
alpha-actinin rich "cytoplasmic densities" associated with cell membranes
53
how do smooth muscles contract
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
where are dense bodies found
beneath plasma membrane and in the cytoplasm and contain site of insertion of actin filaments
55
is there myosin filaments in smooth muscle
yes!
56
regenerative capacity of the three types of muscle
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
actin genes
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
how can we distinguish myopathies from neuropathies
histo!!!
59
cardiac muscle 1. macula adherens 2. gap junction 3. fascia adherens
60
cardiac muscle
61
cardiac muscle
62
dense bodies smooth muscle
63
skeletal muscle
64
cardiac muscle (high mag)
65
smooth muscle (low mag)
66
neuromuscular junction
67
skeletal muscle green = A bands black = I bands
68
skeletal muscle with tendon attachment, see bony spicules on either side
69
skeletal muscle
70
muscle sarcomere black = z line grey in middle = m line
71
skeletal muscle green is endomysium black is perimysium
72
green is perimysium, red is muscle fibers
73
skeletal muscle with RBCs around
74
smooth muscle
75
smooth muscle surface calveolae, t tubules
76
smooth muscle
77
neuromuscular junction
78
skeletal muscle triad
79
skeletal muscle SR = sarocplasmic reticulum M = mitochondria
80

Bree - Structures (34 decks)

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