Bpk 142 > skeletal muscle > Flashcards

skeletal muscle Flashcards

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1
Q

what property makes muscle cells unique

A

contractility - ability to shorten and develop tension

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2
Q

what are the three types of muscle tissue

A
  1. skeletal
  2. smooth
  3. cardiac
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3
Q

skeletal muscle characteristics

A
  • striated
  • voluntary control
  • attaches to skeleton
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4
Q

% body weight skeletal muscle

A

women - 36%
men - 42%

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5
Q

composition of skeletal msuucle

A
  • 75% water
  • 20% protein
    remainder = salts, pigments, fats, carbs
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6
Q

smooth muscle characteristics

A
  • involuntary
  • no striations
  • hollow organs and vessels
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7
Q

cardiac muscle characteristics

A
  • striated
  • involuntary
  • heart wall
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8
Q

primary functions of skeletal muscle

A
  • Movement
  • Maintain posture
  • Breathing (diaphragm)
  • Stabilize joints
  • Support soft tissues
  • Generate heat
  • Guard body openings
  • Chewing/talking
  • Nutrient reserves
  • Endocrine function
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9
Q

how do muscles stabilize joints

A

pull on bones while strengthening

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10
Q

why are muscles impoortant for thermoregulation

A

generate heat during contraction

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11
Q

what are myokines

A

signalling proteins secreted by contracting skeletal muscle

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12
Q

why are myokines important

A

cross-talk with other organs: contribute to exercise benefits

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13
Q

criteria used to name muscles

A
  • Shape
  • Action
  • Location
  • Divisions
  • Size
  • Fiber direction
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14
Q

example of naming by shape

A

deltoid. triangular

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15
Q

example naming by size

A

gluteus maximus/minimus

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16
Q

fiber direction examples

A

transverse (across), rectus (straight)

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17
Q

parallel fascicle characteristics

A

Greater ROM, less strength

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18
Q

pennate architecture characteristics

A

smaller ROM, greater strength

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19
Q

types of pennate muscles

A
  • unipennate - bipennate
  • multipennate
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20
Q

example multipennate muscle

A

deltoid

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21
Q

primer mover definition

A

main muscle responsible for movement

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22
Q

antagonist definition

A

muscle opposing the prime mover

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23
Q

fixator/stabilizer defintion

A

immobilizes joint near origin

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24
Q

origin

A

less moveable, usually proximal end

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25
insertion
more moveable, usually distal end
26
belly
widest portion of muscle
27
endomysium surrounds
individual muscle fibers
28
perimysium surrounds
fasciculi
29
epimysium surrounds
whole muscle
30
function of connective tissue layers
maintain intramuscular pressure and augment force
31
function of tendons
transmit force from muscle to bone
32
muscle fiber contains what
many myofibrils
33
myofibrils composed of
repeating sarcomeres
34
sarcomere contains what proteins
actin (thin), myosin (thick)
35
sliding filament theory
myosin cross-bridges attach to actin, rotate with ATP - sarcomere shortens
36
why large blood supply
muscle metabolic rate can increase 100x
37
capillaries per fiber (sedentary)
3-4
38
capillaries per fiber (trained0
up to 7
39
at what % max force does blow flow restrict
15-20%
40
at what % max force can blood flow halt
50%
41
define motor unit
motor neuron + all fibers it innervates
42
average fibers per motor unit
200
43
fine control muscles motor unit size
2-3 fibers
44
gross movement muscles unit size
up to 2000 fibers
45
all or none law
all fibers in motor unit contract if threshold reached
46
slow twitch name
type I (SO)
47
fast oxidative-glycolytic
type IIa (FOG)
48
fast glycolytic
type IIx (llb)
49
which fiber type has highest fatigue resistance
slow oxidative (type I)
50
which produces highest force
fast glycolytic (IIx)
51
which has highest mitochonria count
slow oxidative
52
which has highest glycolytic enzyme activity
fast glycolytic
53
which fiber type is red
slow oxidative
54
which fiber type is while
fast glycolytic
55
two ways to increase muscle force
- motor unit summation - frequency (wave) summation
56
frequency summation can increase fore by
5x single twitch
57
size principle
small motor units recruited first, larger ones as intensity increases
58
optimal force occurs at what length
slightly stretched resting length
59
why reduced force at very short/long lengths
fewer cross-bridge formations
60
faster shortening
less force
61
velocity = 0 = ?
isometric contraction
62
negative velocity
eccentric contraction
63
eccentric can produce for force than
concentric shortening
64
power formula
power = force x velocity
65
power - velocity relationship shape
inverted U
66
max power occurs at
1/2 max velocity & 1/3 max concentric force
67
max rotational force occurs at what angle
90 degrees
68
at >90 degrees what increases
stabilizing component
69
define sarcopenia
age-related loss of skeletal muscle mass, strength, and function
70
muscle loss per decade after 30
3-8%
71
muscle loss per year after 50
1-2%
72
causes of sarcopenia
- Neural apoptosis - Protein imbalance - Mitochondrial decline - Inactivity - Hormonal decline - Poor nutrition
73
sarcopenia increases risk of
- Disability (4.5× higher risk) - Dependency - Medical costs
74
can exercise reverse sarcopenia
it can slow/reduce it - not stop aging
Bpk 142
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