01:119:116 Lecture Notes - Lecture 21: Rigor Mortis, Collagen, Osteoporosis
Document Summary
Lecture 21 - musculoskeletal system: vertebrate skeletal muscle, introduction to muscle. Muscle tissue generates mechanical force in response to nervous system (what?) T (transverse) tubules connect to impulses to Thin filaments have 3 types of proteins. Sarcomere - basic unit of contraction within myofibril. Z lines - join sarcomeres at ends. Thick filaments anchor at m (center in sarcomere) Thick and thin filaments slide & break old connections. Form new ones - sarcomere gets shorter. Overlap changes - not length of filament: sliding filament model, muscle fiber at rest. Tropomyosin covers myosin binding sites of actin. Fig 50. 29: motor neuron transmit ap. Motor unit - connects with ~ 150 muscle fibers. Plasma membrane down t-tubules sr. Later ca2+ pump returns ca2+ to sr. Fig 50. 28: contraction, ca2+ binds to troponin complex on thick filaments, now it is ready to contract, myosin is an atpase - splits atp. Eventually the bridges will break as actin & myosin break down.