BIOM20002 Lecture Notes - Lecture 14: Rigor Mortis, Myocyte, Myosin
Document Summary
Rigor state: an attached crossbridge with no atp bound. Rigor mortis - muscles no longer able to bind more atp so crossbridges remain. Myosin heads aren"t all doing this in sync. This is one filament in a sarcomere which is in a muscle fibre. Binding of ca2+ to troponin pulls tropomyosin away from g-actin binding site, allowing myosin to bind. Because aceyltcholine binds to receptors, ca channels open but nothing comes in. If we stimulated muscle directly then we would get a muscle contraction since muscle fibre still has sr. Isometric contraction: generating force but no change in length of muscle. Muscle does not shorten because it hasn"t exerted enough force to overcome the load. The stimulus shortens cc pulling up on the elastic component (the spring) All myosin heads move along actin in the same direction. The contractile components contract but the elastic component elongates. Muscle shortens because force of contraction is able to lift load.
