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2017 physiology > Exam 3 (chapter 12 part 3) > Flashcards

Exam 3 (chapter 12 part 3) Flashcards

1
Q

more muscle fibers contracting = ____________ force

A

more

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2
Q

stimulating more muscle fibers to contract

A

recruitment

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3
Q

bundle of muscle fibers

A

muscle

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4
Q

more muscle fibers contracting = _____________ overall muscle ____

A

greater

tension

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5
Q

recruitment occurs at the level of the ___________ ____________

A

motor unit

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6
Q

activation of the motor neuron activates _________ muscle fibers in the motor unit

A

all

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7
Q

increases in tension occur in steps _______________ to the size of the motor unit

A

proportional

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8
Q

muscles for delicate movements

A

small motor units (often inervate type 1)

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9
Q

muscles for stregth

A

large motor units

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10
Q

fiber diameter for weaker movements

A

lower

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11
Q

fiber diameter for stronger movements

A

higher

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12
Q
  • small fibers
  • small motor neuron cell bodies
  • small axon diameters
A

small motor units

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13
Q
  • large fibers
  • large motor neuron cell bodies
  • large axon diameters
A

large motor units

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14
Q

order of motor unit recruitment is related to size of motor units

  • small units recruited first
  • large units recruited second
A

ye

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15
Q

small motor units are recruited _____________ while large motor units are recruited ______________

A

first

last

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16
Q

are larger neurons more or less difficult to depolarize to threshold?

A

more (requires greater synaptic input)

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17
Q

how muscle cells generate ATP

A

muscle metabolism

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18
Q

___________ is required by muscle to generate work (contraction)
- drive cross bridge cycling

A

ATP

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19
Q

what drives cross bridge cycling?

A

ATP

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20
Q

what are a muscle cells 3 sources of ATP?

A

phosphorylation of ADP by creatine phosphate (shortest), oxidative phosphorylation of ADP (in mitochondria), anaerobic glycolysis

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21
Q

what is the role of creatinine/creatine phosphate system?

A

small store of ATP at rest (must quickly increase ATP synthesis) roughly 12 seconds

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22
Q
  • use of ATP drives reaction to the right (need to make more)
  • can only supply up to 5x the quantity of ATP
A

law of mass action

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23
Q

during light to moderate exercise, what supplies glucose initially?

A

glycogen (carb stores)

24
Q

after 30 min of light to moderate exercise, what is in the blood?

A

glucose, fatty acids (broken down for energy)

25
Q

when O2 is needed during light to moderate exercise, ventilation _____________, heart rate and contraction _____________, and vessels to muscle __________________,

A

increases, increases, dilates

26
Q

during light to moderate exercise there is a transient _____________ in GLUT4

A

increase

27
Q

during heavy exercise, what supplies ATP?

A

anaerobic glycolysis (lactate)

28
Q

what is the rate limiting step of the cycle?

A

ATP hydrolysis

29
Q

higher rate of ATP hydrolysis = _______________ cross bridge cycling

A

faster

30
Q

myosin with fast ATPase activity

  • contract 2-3 times more rapidly
  • relax more rapidly
A

fast fibers (2a, 2x)

31
Q

myosin with slow ATPase activity

- last 10x longer

A

Slow fibers (1)

32
Q
  • anaerobic glycolysis
  • fewer mitochondria
  • many glycolytic enzymes
  • high glycogen stores
  • use little oxygen
  • large diameter
  • quick to fatigue
A

glycolytic fibers

33
Q
  • oxidative phosphorylation
  • many mitochondria
  • myoglobin (red)
  • small diameter
  • resistant to fatigue
  • many capillaries
A

oxidative fibers

34
Q

what are the 3 skeletal muscle fiber types?

A

1 (slow oxidative), 2a (fast oxidative), 2x (fast glycolytic)

35
Q
  • low myosin ATPase
  • high oxidative capacity (aerobic)
  • small diameter
  • fatigue slowly (endurance)
A

slow oxidative fibers (type 1)

36
Q
  • high myosin ATPase activity
  • high glycolytic capacity
  • no myoglobin
  • large diameter
  • fatigue rapidly
A

fast glycolytic fibers (2x)

37
Q
  • intermediate myosin ATPase activity
  • high oxidative capacity
  • myoglobin
  • slow to fatigue, but more rapid than slow oxidative fibers
  • intermediate diameter
A

fast oxidative fibers (2a)

38
Q

An oxygen-storing, pigmented protein in muscle cells.

- consists of a backbone and heme-binding domain

A

myoglobin

39
Q

slow oxidative (red, type 1):

  • oxidative capacity?
  • glycolytic capacity?
  • speed of contraction?
  • myosin ATPase activity?
  • mitochondrial density?
  • capillary density?
  • myoglobin content?
  • resistance to fatigue?
  • fiber diameter?
  • motor unit size?
  • force generating capacity?
A

slow oxidative (red, type 1):

  • oxidative capacity: high
  • glycolytic capacity: low
  • speed of contraction: slow
  • myosin ATPase activity: low
  • mitochondrial density: high
  • capillary density:high
  • myoglobin content: high
  • resistance to fatigue: high
  • fiber diameter: small
  • motor unit size: small
  • force generating capacity: low
40
Q

Fast oxidative (pink, type 2a):

  • oxidative capacity?
  • glycolytic capacity?
  • speed of contraction?
  • myosin ATPase activity?
  • mitochondrial density?
  • capillary density?
  • myoglobin content?
  • resistance to fatigue?
  • fiber diameter?
  • motor unit size?
  • force generating capacity?
A

Fast oxidative (red):

  • oxidative capacity: high
  • glycolytic capacity: intermediate
  • speed of contraction: intermediate
  • myosin ATPase activity:intermediate
  • mitochondrial density: high
  • capillary density: high
  • myoglobin contenthigh
  • resistance to fatigue: intermediate
  • fiber diameter: intermediate
  • motor unit size: intermediate
  • force generating capacity: intermediate
41
Q

Fast glycolytic (white):

  • oxidative capacity?
  • glycolytic capacity?
  • speed of contraction?
  • myosin ATPase activity?
  • mitochondrial density?
  • capillary density?
  • myoglobin content?
  • resistance to fatigue?
  • fiber diameter?
  • motor unit size?
  • force generating capacity?
A

Fast glycolytic (white):

  • oxidative capacity: low
  • glycolytic capacity: high
  • speed of contraction: fast
  • myosin ATPase activity: high
  • mitochondrial density: low
  • capillary density: low
  • myoglobin content: low
  • resistance to fatigue: low
  • fiber diameter: large
  • motor unit size: large
  • force generating capacity: high
42
Q

each muscle is a ____________ of fiber types

A

mixture

43
Q

in a single motor unit, do all muscle fibers have to be of the same type?

A

yes

44
Q

can you change myosin ATPase activity?

A

no (born with)

45
Q

what does oxidative capacity mean?

A

oxidative phosphorylation

46
Q

speed of contraction depends on what?

A

ATP hydrolysis (ATPase activity)

47
Q

can you change capillary density?

A

yes

48
Q

can you change myoglobin content?

A

yes

49
Q

can you change resistance to fatigue?

A

yes

50
Q

can you change fiber diameter?

A

yes

51
Q

can you change force generating capacity?

A

yes

52
Q

large diameter = ____________ sarcomeres in parallel

A

more

53
Q

can you change muscle fiberr number

A

no

54
Q

does having a small or large diameter make O2 delivery more efficient?

A

small (type 1 prevalence)

55
Q

what is recruitment order of the skeletal muscle fiber types?

A

1 (slow oxidative), 2a (fast oxidative), 2x (fast glyoclytic)

56
Q

what is an example of a time when fast glycolytic fibers are being used?

A

sprinting

57
Q

what is an example of a time when slow oxidative fibers are being used?

A

long distance running

2017 physiology (20 decks)

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