BIOLOGY 173 Lecture Notes - Lecture 26: Endoplasmic Reticulum, Myosin Head, Atp Hydrolysis
Document Summary
Shorting of the sarcomere by the contraction cycle. Myosin heads swivel and move thin filaments to sarcomere center and shorten sarcomere. Myosin head binds to active site on actin. Adp and p are still bound to the head: cross-bridge rotation (pivoting) Adp and p exit the myosin head: cross-bridge detachment. Review of the steps involves in muscle contraction. Cross-bridges form when myosin heads bind to those active sites: contraction cycle begins: the contraction cycle begins as repeated cycles of cross-bridge binding, pivoting, and detachments occur all powered by atp. All or none principle: after stimulation by a nerve, and individual muscle cell either contracts to its fullest or not at all. Response of entire muscle (organ) to stimulation according to the principle of grated strength: single stimulus. Twitch response of a muscle to a single stimulus. Relaxation sarcomeres lengthen: summation adding individual twitches together. Increased force of contraction caused by an increase in stimulus strength.