BIO 3137 Study Guide - Final Guide: Chromatophore, Anterior Pituitary, Nephron
23 Feb 2017
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Document Summary
In muscle cells, myosin and actin serve as motor molecule and structural element, respectively. Actin filament contains myosin head binding sites and myosin has an atpase that breaks down atp to produce energy for movement. Skeletal muscle is composed of repeating units called sarcomeres and this arrangement gives it a striated appearance. An increase in [ca2+]intracellular acts as the trigger for contraction. Skeletal muscles can be fast- or slow-twitch types, with each having a different myosin isoform, providing different rates of atpase activity and crossbridge cycling. Fast-twitch fibres that use glycolysis and oxidative phosphorylation for atp production can produce intermediate contractions but sustain the contraction for a long period. Fast-twitch fibres that use only glycolysis for atp production can produce strong contractions but fatigue quickly due to lactic acid accumulation. Skeletal muscles are activated by motor neurons in an all-or-none fashion.
