KINE 4010 Lecture Notes - Lecture 6: Motor Unit, Oxidative Phosphorylation, Tetanic Contraction
26 Sep 2015
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Lecture 6: skeletal muscle muscle acts as endocrine organ comprises 40% of body mass. 3 types of muscle: skeletal, cardiac, smooth smooth & cardiac: involuntary control skeletal: voluntary control motor cortex spinal cord a-motorneurons w in nerve mu. Mu (motor unit) = nerve + all the bres it innervates all bres in the mu have the same contractile & metabolic properties can have small mu or larger mu. Rate of contraction determined by myosin isoform (i,iia,iix) and rate of ca release. Rate of relaxation determined by ca uptake rate by sr (ca atpase) and [parvalbumin] (protein; absorbs excess ca; higher concentrations in fast-twitch bres) Motor units and their fibre types: di erences depend on: size of bres, # bres, size of cell body. Str: slow twitch red (a lot of mitochondria, a lot of capillary to bre ratio; higher oxidative capacity & less glycolysis; uses oxidative phosphorylation for atp) more fatigue resistant small ber, fewer # bres, small cell body.
