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Biology II > ch. 50 muscles > Flashcards

ch. 50 muscles Flashcards

1
Q

what does muscle cell contraction rely upon

A

interaction between thick and thin filaments

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2
Q

thin filament composition

A

mostly actin

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3
Q

thick filament composition

A

staggered arrays of myosin

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4
Q

what does vertebrae skeletal muscle move

A

bones and the body

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5
Q

what does a skeletal muscle consist of

A

bundle of long fibers, each a single cell, running along length of muscle

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6
Q

what is each muscle fiber composed of

A

bundle of smaller myofibrils arranged longitudinally

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7
Q

why is skeletal muscle striated

A

regular arrangement of myofilaments creates a pattern of light and dark bands

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8
Q

functional unit of muscle

A

sarcomere

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9
Q

what is a sarcomere bordered by

A

Z lines - where thin filaments attach

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10
Q

sliding filament model

A

thin and thick filaments ratchet past each other longitudinally, powered by myosin molecules

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11
Q

regions of each myosin

A

long tail and globular head

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12
Q

what does the head of the myosin molecule bind to

A

actin filament to form cross-bridge and pull thin filament toward the center of the sarcomere

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13
Q

what generates ATP needed to sustain muscle contraction

A

glycolysis and aerobic respiration

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14
Q

what happens when oxygen becomes limiting during intense muscle activity

A

ATP generated by lactic acid fermentation
- sustains contraction for only about 1 minute

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15
Q

steps of sliding filament model

A
  1. myosin head with low-energy configuration (ATP)
  2. with high-energy configuration (ADP + P) binds to binding sites on actin
  3. forms cross bridge
  4. thin filament moves toward center of sarcomere
  5. ATP back to myosin head
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16
Q

tropomyosin and troponin complex

A

set of additional proteins that bind to actins strands on thin filaments when a muscle fiber is at rest to prevent actin and myosin from interacting

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17
Q

how are myosin-binding sites exposed

A

Ca2+ binds to troponin complex

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18
Q

stimulus leading to contraction of a muscle fiber

A

action potential in motor neuron that makes a synapse with the muscle fiber

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19
Q

what does the synaptic terminal of the motor neuron release

A

neurotransmitter acetylholine

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20
Q

what does acetylcholine do

A

depolarize muscle, causing it to produce an action potential

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21
Q

transverse (T) tubules

A

where action potentials travel to the interior of the muscle

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22
Q

sarcoplasmic reticulum

A

releases Ca2+ from action potential in T tubules

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23
Q

what happens when motor neuron input stops

A
  • muscle cell relaxes
  • transport proteins in SR pump Ca2+ out of cytosol
  • regulatory proteins bound to thin filaments shift back to their starting positions
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24
Q

steps at neuromuscular junction

A
  1. action potential arrives at synaptic terminal
  2. acetylcholine released
  3. binds at motor end plate
  4. sodium ions then rush into postsynaptic cell
  5. action potential appears in sarcolemma
  6. returns to initial state
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25
Q

amyotrophic lateral sclerosis

A

(Lou Gehrig’s disease) interferes with excitation of skeletal muscle fibers
- usually fatal

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26
Q

myasthenia gravis

A

autoimmune disease that attacks acetylcholine receptors on muscle fibers
- treatments exist

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27
Q

what is the contraction of the whole muscle?

A

graded - extent and strength of contraction can be voluntarily altered

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28
Q

2 basic mechanisms by which the nervous system produces graded contractions

A
  1. varying number of fibers that contract
  2. varying rate at which fibers are stimulated
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29
Q

motor unit

A

single motor neuron and all the muscle fibers it controls

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30
Q

recruitment

A

process by which more and more motor neurons are activated

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31
Q

what happens as recruitment proceeds

A

force developed by a muscle increases

32
Q

twitch

A

results from single action potential in a motor neuron

33
Q

what do more rapidly delivered action potentials produce

A

graded contraction through summation

34
Q

tetanus

A

state of smooth/sustained contraction produced when the rate of stimulation is so high that muscle fibers cannot relax between stimuli

35
Q

what are types of skeletal muscle fibers classified by

A
  1. source of ATP powering muscle activity
  2. speed of muscle contraction
36
Q

3 types of skeletal muscle fibers

A
  1. slow oxidative
  2. fast oxidative
  3. fast glycolytic
37
Q

slow oxidative

A
  • slow contraction speed
  • aerobic respiration
  • slow rate of fatigue
  • many mitochondria
  • high myoglobin content
38
Q

fast oxidative

A
  • fast contraction speed
  • aerobic respiration
  • intermediate rate of fatigue
  • many mitochondria
  • high myoglobin
39
Q

fast glycolytic

A
  • fast contraction speed
  • glycolysis
  • fast rate of fatigue
  • few mitochondria
  • low myoglobin
40
Q

oxidative fibers

A
  • rely on aerobic respiration to get ATP
  • have many mitochondria
  • rich blood supply
  • large amount of myoglobin
41
Q

myoglobin

A

protein that binds oxygen more tightly than hemoglobin does

42
Q

glycolytic fibers

A
  • glycolysis as primary source of ATP
  • less myoglobin
  • larger diameter
  • tire more easily
43
Q

what is light meat composed of

A

glycolytic fibers

44
Q

what is dark meat composed of

A

oxidative fibers

45
Q

fast-twitch fibers

A

enable brief, rapid, powerful contractions
- glycolytic or oxidative

46
Q

slow-twitch fibers

A

contract more slowly but sustain longer contractions
- less sarcoplasmic reticulum than fast fibers
- pump Ca2+ more slowly
- all oxidative

47
Q

cardiac muscle

A
  • found only in heart
  • striated cells
  • electrically connected by intercalated disks
48
Q

how does cardiac muscle generate action potentials?

A

without neural input

49
Q

where is smooth muscle foudn

A

walls of hollow organs (circulatory, digestive, reproductive)

50
Q

smooth muscle contractions

A
  • slow and may be initiated in muscles themselves
  • may also be caused by stimulation from neurons in autonomic nervous system
51
Q

why does smooth muscle lack striations

A

actin and myosin not regularly arrayed

52
Q

is smooth muscle regulated by Ca2+?

A

yes but mechanism different

53
Q

how are skeletal muscles attached

A

in antagonistic pairs - actions coordinated by nervous system

54
Q

skeleton function

A

support, protection, and movement

55
Q

3 main types of skeletons

A
  1. hydrostatic (fluid-based support)
  2. exoskeleton (external hard parts)
  3. endoskeletons (internal hard parts)
56
Q

hydrostatic skeleton

A

fluid held under pressure in a closed body compartment

57
Q

main type of skeleton in cnidarians, flatworms, nematodes, and annelids

A

hydrostatic skeleton

58
Q

how to annelids use hydrostatic skeleton

A

for peristalsis - movement produced by rhythmic waves of muscle contractions from front to back

59
Q

exoskeleton

A

hard covering deposited on the surface of an animal

60
Q

skeleton of molluscs and arthorpods

A

exoskeleton

61
Q

cuticle

A

jointed exoskeleton of arthropods which can be both strong and flexible

62
Q

chitin

A

polysaccharide often found in arthropod cuticle

63
Q

endoskeleton

A

hard internal skeleton buried in soft tissue

64
Q

skeleton in organisms from sponges to mammals

A

endoskeleton

65
Q

what do vertebrate endoskeletons consist of

A

cartilage bone, or combination

66
Q

mammalian skeleton

A
  • 200+ bones
  • some fused together
  • other connected at joints by ligaments
67
Q

what is the position of legs relative to the body important for in mammals and birds

A

determining how much weight the legs can bear

68
Q

locomotion

A

active travel from place to place

69
Q

why is energy expended in locomotion

A

to overcome friction and gravity

70
Q

air and locomotion

A

air poses little resistance

71
Q

what is a prerequisite to walking, running, or hopping

A

maintaining balance

72
Q

crawling challenge

A

must exert energy to overcome friction

73
Q

challenge of locomotion in water

A

friction bigger problem than gravity

74
Q

how do animals swim

A
  • paddling with legs as oars
  • jet propulsion
  • undulating body and tail from side/side or up/down
75
Q

what does active flight require

A

wings that develop enough lift to overcome downward force of gravity

Biology II (43 decks)

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