Lecture 13: Muscle 7 Flashcards
Three types of skeletal muscle fibers
- Slow oxidative (Type I)
- Fast oxidative (Type IIA)
- Fast glycolytic (Type IIB)
Smallest skeletal muscle fiber
slow oxidative
Slow oxidative fibers are also called
Slow-twitch
Fatigue-resistant
Slow oxidative and fast oxidative contain large amounts of
- Myoglobin
- Mitochondria
- Blood capillaries
Slow oxidative and fast oxidative color
red
Slow oxidative and fast oxidative potential to generate ATP
high
Slow oxidative split ATP at a slow rare and as a result have a slow
contraction velocity
Slow oxidative are resistant to
fatigue
Slow oxidative are found in large numbers where?
- Postural muscles
- Ex. Neck, legs
Fiber with intermediate diameter
fast oxidative
What are some other names for fast oxidative fibers
Fast-twitch A
Fatigue resistant
Fast oxidative split ATP at a fast rate, thus
contraction velocity is fast
Because fast oxidative rate of ATP production by oxidative phosphorylation cannot keep pace with the high rate of ATP splitting, they rely
partially on glycolysis and are more prone to fatigue than slow oxidative fibers
Fast oxidative are well adapted for
jumping and sprinting
What fibers are the largest in diameter?
Fast glycolytic
What are two other names for fast glycolytic fibers
Fast twitch B
Fatigable
Fast glycolytic fibers have low
myoglobin content
few mitochondria
few blood capillaries
Fast glycolytic fibers have large amounts of
glycogen
What color are glycolytic fibers?
white
How do fast glycolytic fibers generate ATP?
By anaerobic processes (glycolysis)
What fibers fatigue easily?
Fast glycolytic fibers
Skeletal muscles are a mix of
all three types of fibers
Can fibers of any one motor unit be different types?
Nope
What are recruited for maximal contraction?
Fast glycolytic
Activation of various motor units is determined by
The CNS
