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Anatomy and Physiology I > Lesson 20 > Flashcards

Lesson 20 Flashcards

1
Q

muscle means literally…

A

little mouse

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2
Q

muscular system refers only to…

A

skeletal muscle

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3
Q

myology

A

the study of the muscular system

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4
Q

excitability (responsiveness)

A

respond to chemical signals, stetch, and electrical changes across the plasma membrane

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5
Q

conductivity

A

local electrical excitation sets off a wave of excitation that travels along the muscle fiber

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6
Q

contractility

A

shorten when stimulated

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7
Q

extensibility

A

capable of being stretched between contractions

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8
Q

elasticity

A

returns to its original rest length after being stretch

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9
Q

striations

A

alternating light and dark transverse bands; results from arrangement of internal contractile proteins

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10
Q

voluntary

A

usually subject to conscious control

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11
Q

skeletal muscle cells are also called _____ _____ or _____

A

muscle fibers, myofibers

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12
Q

six functions of skeletal muscle

A
  1. produce skeletal movement
  2. maintain posture and body position
  3. support soft tissues
  4. guard entrances and exits
  5. maintain body temperature
  6. store nutrients
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13
Q

endomysium

A

fibrous connective tissues that surrounds each muscle fiber

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14
Q

perimysium

A

bundles muscle fibers into fascicles

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15
Q

epimysium

A

surrounds entire muscle

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16
Q

collagen (4)

A
  • stretches slightly under tension and recoils when released
  • resists excessive stretching to protect muscle from injury
  • returns muscle to original length
  • contributes power output and muscle efficiency
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17
Q

fascicles

A

bundles of muscle fibers wrapped together

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18
Q

fascia

A

sheet of connective tissue between muscles or muscle groups

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19
Q

what does the endomysium allow room for?

A

capillaries and nerve fibers

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20
Q

what type of cells does the endomysium contain?

A

myosatellite cells (stem cells) that repair damage to muscle cells
CANNOT DEVELOP INTO A WHOLE MUSCLE

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21
Q

what does the perimysium contain? (3)

A

nerves, blood vessels, and stretch receptors

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22
Q

tendon

A

when the endomysium, perimysium, and epimysium come together to form a connective tissue attachment to bone

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23
Q

sarcolemma

A

plasma membrane for a muscle fiber (cell)

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24
Q

sarcoplasm

A

cytoplasm of a muscle fiber

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25
Q

myofibrils

A

long protein cords occupying most of the sarcoplasm

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26
Q

glycogen

A

carbohydrate store to provide energy for exercise

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27
Q

myoglobin

A

red pigmented protein that binds oxygen and provides some needed for muscle activity

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28
Q

sarcoplasmic reticulum (SR)

A

smooth ER that forms a network around each myofibril, that stores calcium in the cell

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29
Q

terminal cisterns

A

dilated end-sacs of SR which cross the muscle fiber from one side to the other

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30
Q

transverse (T) tubules (2)

A

tubular infoldings of the sarcolemma which penetrate through the cell and emerge on the other side
- funnels action potentials generated in the muscle cell towards the terminal cisterns of the SR

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31
Q

triad

A

a T tubule and its two associated terminal cisterns

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32
Q

myoblasts

A

stem cells that fuse to form each muscle fiber early in development, each contributing one nucleus

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33
Q

myosatellite cells

A

unspecialized myoblasts remaining between the muscle fiber and endomysium

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34
Q

three kinds of myofilaments

A
  1. thick filaments
  2. thin filaments
  3. elastic filaments (titin)
35
Q

thick filaments

A

made of several hundred myosin molecules

36
Q

myosin structure (3)

A
  • two chains intertwined to form a shaft-like tail and a double globular head
  • heads directed outward in a helical array around the bundle
  • heads on one half angle to the left, while heads on the other half are to the right
37
Q

bare zone

A

middle zone with no heads

38
Q

fibrous (F) actin

A

two intertwined strands of globular (G) actin subunits, each with an active site that can binds myosin

39
Q

F actin is held together by a protein called _____ that runs along the length of the F actin strand

A

nebulin

40
Q

tropomyosin

A

regulatory protein that blocks the active sites of G actin subunits

41
Q

troponin

A

small, calcium-binding protein on each tropomyosin molecule

42
Q

elastic filaments

A

made of a huge, springy protein called titin

43
Q

what do elastic filaments do? (2)

A
  • help stabilize and position the thick filament
  • prevent overstretching and provide recoil
44
Q

where is titin located?

A

they run through the core of the thick filament and anchor it to Z disc and M line

45
Q

contractile proteins

A

myofilaments, myosin, and actin

46
Q

regulatory proteins

A

tropomyosin and troponin

47
Q

how is contraction activated?

A

by the release of calcium from the SR into the sarcoplasm, binding to troponin

48
Q

A band

A

dark band

49
Q

H band

A

at the middle of the A band, thick filaments only

50
Q

M line

A

dark, transverse protein in the middle of the H band

51
Q

I band

A

light band, only thin filaments

52
Q

Z line

A

protein complex that provides anchorage for thin and elastic filaments

53
Q

sarcomere

A

smallest functional unit of muscles
- segment from Z line to Z line

54
Q

zone of overlap

A

area of the A band minus the H band

55
Q

skeletal muscle cannot contract unless.

A

stimulated by a nerve

56
Q

denervation atrophy

A

shrinkage of paralyzed muscle when nerve remains disconnected; motor neuron no longer stimulating the muscle cell

57
Q

skeletal muscles are served by _____ _____ _____

A

somatic motor neurons

58
Q

somatic motor neurons

A

nerve cells whose cell bodies are in the brainstem and spinal cord that serve skeletal muscles

59
Q

somatic motor fibers

A

axons of somatic motor neurons

60
Q

motor unit

A

one nerve fiber and all the muscle fibers innervated by it; they behave as a functional unit

61
Q

muscle fibers of one motor unit….. (4)

A
  • are dispersed throughout muscle
  • contract in unison
  • produce weak contraction over wide area
  • provide ability to sustain long-term contraction as motor units take turns contracting
62
Q

effective contraction usually requires contraction of …..

A

several motor units at once

63
Q

small motor units

A

provide fine degree of control

64
Q

large motor units

A

provide more strength than control

65
Q

neuromuscular junction (NMJ)

A

aka motor end plate
- when a nerve fiber meets its muscle fiber target at a synapse

66
Q

muscle cell sarcolemma have millions of what kind of receptor?

A

acetylcholine

67
Q

postsynaptic membrane folds (junctional folds)

A

folds of the sarcolemma that increase the surface area, maximizing the number of ACh receptors

68
Q

myasthenia gravis

a lack….

A

a lack of ACh receptors in muscle cells causing weakness

69
Q

acetylcholinesterase

A

enzyme that breaks down ACh, allowing for relaxation

70
Q

muscle fibers and nerve cells are what kind of cell?

A

electrically excitable cells

71
Q

electrophysiology

A

study of the electrical activity of cells

72
Q

electrical activity depends the concentration differences of ions in what two places?

A

intracellular fluid and extracellular fluid

73
Q

polarized

A

contains a net negative charge

74
Q

electrical potential/voltage

A

any difference in charge between two points

75
Q

cholinesterase inhibitors

A

bind acetylcholinesterase and prevents it from degrading ACh

76
Q

spastic paralysis

A

a state of continual contraction of the muscles; possible suffocation

77
Q

tetanus (lockjaw)

A

a form of spastic paralysis caused by toxin Clostridium tetani

78
Q

_____ in the spinal cord normally stops motor neurons from producing unwanted muscle contractions

A

glycine

79
Q

what does tetanus toxin do?

A

blocks glycine release in the spinal cord and causes overstimulation and spastic paralysis of muscles

80
Q

flaccid paralysis

A

a state in which the muscles are limp and cannot contract

81
Q

curare

A

competes with ACh for receptor sites, but does not stimulate muscles

82
Q

botulism

A

type of food poisoning caused by neuromuscular toxin secreted by the bacterium Clostridium botulinum

83
Q

what does botulism toxin do?

A

blocks release of ACh causing flaccid paralysis

84
Q

botox is really just

A

Clostridium botulinum toxin

Anatomy and Physiology I (22 decks)

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