BIPN 100 Lecture Notes - Lecture 16: Intermediate Filament, Anaerobic Glycolysis, Oxidative Phosphorylation
13 Jun 2018
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BIPN 100 Lecture 16
5/9/2018
• Slow-twitch fibers (Type I)
o Rely primarily on oxidative phosphorylation (need oxygen)
o Low ATPase activity
o Do’ fatigue as fast as the other usle types
o Tonic muscles that need a lot of tension with good endurance→like postural
muscles
o Have a lot of mitochondria and myoglobin (binds oxygen to muscles)
• Fast-twitch fibers
o Do’t hae as uh yogloi, so they look pale hite usle
o Develop tension faster, ut a’t produe as uh tesio
▪ Split ATP more rapidly (hydrolyze it more efficiently)
o Pump calcium into the SR more rapidly
o Fast-twitch glycolytic fibers (Type IIB or Type IIx)
▪ Rely primarily on anaerobic glycolysis
▪ Fatigue the fastest
o Fast-twitch oxidative-glycolytic fiber (Type IIA)
▪ Use oxidative and glycolytic metabolism
• Different muscles have different proportions of these two muscle fibers
• Smooth muscle
o Walls of hollow organs, blood vessels, eyes, glands, skin
o Involuntary
o Small, spindle-shaped cells
o Single nucleus centrally located
o Not striated, not arranged in sarcomeres
o Less myosin
▪ Myosin filaments are longer
▪ Entire surface of filament covered is myosin heads
• Ee he the usle is strethed, it does’t eoe less
effective and cross-bridges can still form
• Like when you have to hold your pee→your bladder stretches and
expands so the myosin heads spread apart, but are still able to
contract later on
o Lacks troponin
o Actin is more abundant
o Extensive cytoskeleton: intermediate filaments and protein dense bodies
▪ Myosin can form cross-bridges with different actin
o No t-tubules→caveolae
o Smooth muscle must operate over a wide range of lengths (muscles that stretch)
o Layers must run in several directions
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