01:377:370 Lecture Notes - Lecture 20: Atp Hydrolysis, Endoplasmic Reticulum, Neuromuscular Junction
12 Sep 2019
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Document Summary
Contraction occurs as myosin and actin slide past one another. Energy is provided by atp hydrolysis (at the globular heads of myosin) Myosin cross-bridges cyclically attach, rotate, and detach from actin filaments. Perform repeated, nonsynchronous strokes-allows for continuous, smooth movements. At any one time, only about 50% of the crossbridges make contact with actin (to form actomyosin) Actin and myosin interact and forms actomyosin. Rowing a boat: myosin is the oars. Atp allows myosin to rotate and attach and to pump ca2+ into the sarcoplasmic reticulum. Atp needs to be present for myosin to detach. Neurons innervate each fiber; nerve impulses crossing from the neuron to the sarcolemma (muscle fiber membrane) activate the fiber to make it contract. When you die you are no longer creating atp. Atp will not be available to break the cross-bridge bond contraction will not cease. Ca2+ is still bound to troponin, so tropomyosin will still be out of the way, continuing contraction.
