ANAT 025 Lecture Notes - Lecture 4: Skeletal Muscle, Myocyte, Myofibril
25 May 2020
School
Department
Course
Professor
Document Summary
Skeletal muscle fibers are long, cylindrical cells that contain multiple nuclei and other organelles. Contains many glycosomes for glycogen storage, as well as myoglobin for o2 storage. Myoglobin stores oxygen and gives the red pigment to muscle. Smallest contractile unit (functional unit) of muscle fiber. Contains a band with half of an i band at each end. Individual sarcomeres align end to end along myofibril, like boxcars of train. Orderly arrangement of actin and myosin myofilaments within sarcomere. Single muscle fiber can contain 1000s of myofibrils. Accounts for ~80% of muscle cell volume. Striations: stripes formed from repeating series of dark and light bands along length of each myofibril. H zone: lighter region in middle of dark a band line of protein (myomesin) that bisects h zone vertically. Z disc (line): coin-shaped sheet of proteins on. Extend across i band and partway in a band. Sarcomere cross section shows hexagonal arrangement of one thick filament surrounded by six thin filaments.
