ANA300Y1 Lecture Notes - Lecture 5: Skeletal Muscle, Myocyte, Epimysium
Document Summary
Word roots used in reference to muscle tissue: sarcos (gr. Muscle ); e. g. endomysium, perimysium, epimysium. Muscle tissue specialization for contraction voluntary or involuntary striated (see stripes) or smooth (nonstriated) Skeletal muscle: organization and connective tissue coverings. Skeletal muscle fibres are large, multinucleate cells. Multinuclei = formed by the fusion of multiple mesodermal cells. Muscle fibers develop through the fusion of mesodermal cells called myoblasts. Myoblasts come together, and fuse to form multinuclei cells. More fusion = more nuclei end up with large multinuclei cells. One organized bundle of myofilaments = sarcomeres. Contractile unit of striated muscle this is what shortens. Overall the whole cell does shorten, but it only shortens because each individual sarcomere shortens. Consist of regular arrays of thick and thin filaments. Sarcomeres repeat over the length of the entire cell. Thin filaments composed of actin and its associated proteins. G actin: globular protein. F actin: filamentous polymer of 300- 400 g actin molecules.
