BIO 3422 Lecture 3: Exam 2.1 Notes
16 Dec 2017
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Document Summary
Muscle fiber also known as skeletal muscle cell. These fibers are multinucleated and one muscle fiber may extend the length of the entire muscle. Myofibrils consist of a regular arrangement of thick and thin filaments. The uniform repetitive arrangement of the thick and thin filaments in myofibrils confers the striated (banded) appearance when viewed under microscope. Sarcomere is the functional contractile unit of skeletal muscle cell. Sarcomere is comprised of a very specific arrangement of actin and myosin filaments. Actin molecules attach to the zline and extend toward the center of the sarcomere. Myosin molecules reside in the center of the sarcomere and extend from the m-line outwards. There is overlap of the actin and myosin molecules allowing for interaction. Sliding filament theory of contraction: during muscle contraction, thin and thick filaments interact in such a way as to slide by one another with the actin being pulled toward the center of the sarcomere.
