BIO 11 Lecture Notes - Lecture 13: Multinucleate, Cytoplasm, Aponeurosis
3 Sep 2020
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Document Summary
Threadlike contractile organelles within the sarcoplasm that extend the entire length of the fiber and are composed of filaments. Beneath the endomysium is the plasma membrane of an individual skeletal muscle fiber. Full of contractile proteins arranged in myofibrils. For cardiac and skeletal storage and release area for calcium. Fluid filled system of sacs that encircle each myofibril. T-tubules tiny invaginations of the sarcolemma filled with interstitial fluid. They help propagate the action potentials (electrical signals down the fiber) Terminal cisterns part of the st and align with the t tubules to form a triad. During development, groups of embryonic cells called myoblasts fuse to for individual skeletal muscle fibers. Each muscle fiber contains hundreds of nuclei deep to the sarcolemma. Some myoblasts don"t fuse with developing muscle fibers but remain in tissue as stem cells called myosatellite cells. When injured stem cells differentiate assist in repairing and regenerating muscle. Fibrous network between the skin and underlying muscles and bone.
