PHGY 209 Lecture Notes - Lecture 17: Skeletal Muscle, Myocyte, Myofibril
14 Nov 2016
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3 types of mucle cells: skeletal, cardiac, smooth. Only contracts when nervous system tells it to. Smooth muscle: involuntary contraction in blood vessels, gut, bronchi, uterus. Physiologically, all a muscle cell can do, is contract & relax. Yet, muscle cells action gives rise to all the complicated actions we can perform. When muscle gets shorter (contract), it pulls on the tendon (muscle is attached at each end to tendons, which in turn attach to bone on both sides of a joint). Each individual muscle cell is called muscle fibers (can be quite long -- up to 1 foot!) Stripes are perpendicular to the long axis of muscle fibers. Note that the fibers are all lined up => so when a muscle contracts the efficiency of contraction is maximal. Muscle fibers are long thin cells; multinucleated (black dots shown below) Many many myoblasts fuse together to form a long muscle fiber. Multinucleated so that there could be more protein synthesis.
