BIOLOGY 2A03 Lecture Notes - Lecture 10: Cardiac Muscle, Protein Isoform, Afferent Nerve Fiber
4 May 2017
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Document Summary
Muscle fibre that has myofibrils that has thick and thin filaments (sarcomere for cross- bridge cycle) Muscle cell innervate by single motor neuron: excitation-contraction coupling. Ach bind to nicotinic receptors, na+ in and k+ leave. Ca+ bind to troponin, expose myosin binding site. Myosin need to bind and unbind from actin (ca+ and atp for cross- bridge cycling to occur) Ca+ removed and returned to sarcoplasmic reticulum (sr) Latent period: occurs stimulate, time for ca+ to bind to troponin (no force build up ~ms) Contraction phase: generate maximum tension/force, when all myosin heads bound to actin, ca+ amount is increased. Relaxation phase: peak contraction to 0 force produced, ca+ taken back to sr (muscle relax, ca+ in sarcoplasm is decreasing) Twitch reproducible all or none response, will reduce same amount of ca+ and cross- bridge cycling for same amount of force. Amount of thick/thin filament decides how much force produced (cross- bridge cycling)
