Molecular Exercise Physiology Skeletal Muscle Hypertrophy Seminar 8 Henning Wackerhage.
Skeletal Muscle Physiology
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Transcript of Skeletal Muscle Physiology
Skeletal Muscle Physiology
Muscle excitation and energy sources.• Describe the roles of ATP in muscle
function.
• Explain the sources of ATP for muscle function.
• Muscle elastic elements recoil, muscle returns to resting length.
End of contraction• ACh destroyed by ACh-esterase in synapse• Muscle repolarizes• Ca2+ returned to SR by Ca2+ active transporter• ATP hydrolysis (+Mg) reextends myosin head
Titin is the largest polypeptide known (34,350 amino acids in length). It spans from the M to Z lines.
Energy for muscle function - uses of ATP
for cross-bridge cycle, myosin detachment from actin for Ca2+ return to SR, by active transport for return of Na+, K+ by sarcolemma ATPase pump
Energy for muscle function - sources of ATP
GlucoseCreatine ~PGlucose, fat or protein
+ creatine
Pyruvic acid
(anaerobic)lactic acid
(aerobic) … next slide
Glucose is supplied by stored glucose (as glycogen) and plasma glucose
glucoseOxygen(plasma or myoglobin)
+ Pyruvic acid
+ 36 ATP
Krebs cycleCitric acid cycle
= Cellular respiration
= Aerobic metabolism
Time Course of Contributions from Different Energy Sources
Oxidative
fast twitch glycolytic (white)
slow twitch oxidative (red)
Skeletal Muscle Fiber Types
• innervating nerve is primary determinant of fiber type during development
• a motor unit is composed of homogenous fibers• all human muscles contain mixture of three general
fiber types– slow twitch (ST, oxidative, red)
– fast twitch (FTa, fast-oxidative, red)
– fast twitch (FTb, glycolytic, white)