ANSC 2340 Lecture Notes - Lecture 10: Endoplasmic Reticulum, T-Tubule, Myosin Head
12 Mar 2017
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Document Summary
Theory of muscle contractions: the interaction between actin & myosin for muscle shortening or contraction, natural attraction between actin and myosin versus the regulatory proteins troponin. & tropomyosin (require ca2+ to separate them: conformational change is required on the thin laments. In resting muscles, a regulatory protein, tropomyosin blocks sites on actin where myosin heads attach. Diagram of relaxed and contracted sarcomere muscles: myosin band (a-band) is unaffected, actin band (i-band) shortens upon contraction, and lengthens when relaxed. Theory of muscle contraction: thick laments slide between thin laments. No effect on a band: thin laments are pulled towards the center of the sarcomere, but their length remains constant. Friday, march 10, 2017: muscle contraction involves the action of 4 myo brillar proteins. Troponin & tropomyosin (regulatory proteins: myosin heads grab and swivel along thin laments and move towards the center of the sarcomere, pulling actin with it (image to the right)
