BIOL 3402 Lecture Notes - Lecture 2: Sarcomere, Troponin, Dystrophin
Document Summary
Thick filaments (myosin molecules) golf club shape: heads directed outward (bi-headed) Tropomyosin body guard : blocks myosin from actin, moved by ca, using troponin. Troponin: calcium binding on tropomyosin molecule. Elastic filaments: ends of sarcomere, anchor thin filament to z disc and m line, helps position thick filaments, prevents overstretching/provides recoil. Dystrophin: link actin to membrane protein, unified muscle action. H-bands middle of a-bands: thick filaments only. Z disc anchor for thin filaments & elastic filaments: bisects i-bands. Sarcomere = z disc to z disc. Contraction stimulated by nerve: nerve damage/severed = paralysis, denervation = atrophy. Shrinkage of paralyzed muscle when nerve remains disconnected. Somatic motor neurons: motor fibers (axons) lead to skeletal muscle. Each fiber supplied by one motor neuron. Motor unit = 1 nerve fiber & all muscle fibers innervated by it: muscle fibers of 1 motor unit. Average motor unit = 200 muscle fibers.
