2.25 Motor SC 2 Flashcards
3 muscle fiber types
- Slow twitch
- Fast twitch oxidative-glycolytic
- Fast twitch glycolytic
slow twitch aka
S or Type I
fast twitch oxidative-glycolytic aka
FOG or Type IIa
fast twitch glycolytic aka
FG or Type IIb
Where are slow twitch fibers found? How do they fire?
- found in postural muscles (support)
- fire tonically
slow twitch: contractile force/ATPase
less contractile force with low myosin ATPase activity
slow twitch: metabolism
oxidative metabolism with low glycolytic capacity
slow twitch: blood flow
- dense capillary networks
- high blood flow
slow twitch: mitochondria, myoglobin
- high mitochondrial density
- high myoglobin content
Fast twitch oxidative-glycolytic: contractile force/ATPase
intermediate contractile force and myosin ATPase activity
Fast twitch oxidative-glycolytic: metabolism
both oxidative and glycolytic activity
Fast twitch oxidative-glycolytic: blood flow
intermediate capillary density and blood flow
Fast twitch oxidative-glycolytic: mitochondria, myoglobin
- intermediate mitochondrial density
- intermediate myoglobin content
Fast twitch glycolytic: contractile force/ATPase
more contractile force with high myosin ATPase activity
Fast twitch glycolytic: metabolism
high glycolytic and low oxidative capacity
Fast twitch glycolytic: blood flow
poor capillary networks and low blood flow
Fast twitch glycolytic: mitochondria, myoglobin
- low mitochondrial density
- low myoglobin content
fast twitch fibers: overall (power, fatigue)
- more powerful muscles
- fatigue a lot faster
- for power movements
fatigability: slow twitch
fatigue resistant
fatigability: fast twitch oxidative-glycolytic (Type IIa)
intermediate fatigue resistant
fatigability: fast twitch glycolytic (Type IIb)
high fatigability
motor unit muscle fibers
Motor units contain all of the same type of muscle fibers
types of motor units
- Slow twitch units: S
- Fast twitch fatigue resitant units: FR
- Fast twitch fatigable units: FF
sizing of motor units with respect to type
Sizing: S
