biol 2160-exam 3

biol 2160-exam 3 - Chapter 12. Muscle Physiology Be sure...

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Chapter 12. Muscle Physiology Be sure you know the following: Skeletal Muscle Structure The Mechanism of Force Generation in Muscle The Mechanics of Skeletal Muscle Contraction Types of Skeletal Muscle Fibers Smooth and Cardiac Muscle Classification of Muscle Skeletal muscle; Smooth muscle; Cardiac muscle -effector organ of the SNS is skeletal muscle, where as smooth and cardiac muscle are effector organs of the ANS Structure of a Skeletal Muscle -ex. Biceps: connected to at least 2 bones, except certain skeletal muscles which are connected to skin, cartilage or other muscles - body : “meaty” part of the muscle that generates force; body contains many bundles or fascicles of individual muscle cells as well as connective tissue, blood vessels, and nerves Muscle = group of fascicles (each fascicle contains hundreds or thousands of muscle cells or muscle fibers) Muscle fibers extend length of muscle from tendon to tendon (fig. 12.1)-cords of elastic connective tissue that transmit force from muscle to bone Ex. Eating meat-eating fascicles and muscles fibers Fig. 13.1/13.2: 13.1- structure of a skeletal muscle : representative skeletalmuscles in the arm are shown, as are the tendons that connect them to bones. The enlargement shows the arrangement of muscle fibers within a muscle and some of the structural features of individual muscle fibers. 13.2 - strucutre of a skeletal muscle fiber : major internal components of a muscle fibers are shown. A single myofibril in the muscle fiber has been extended and slightly enlarged to reveal the arrangement of thick and thin filaments within it. The enlarged view shows a magnified image of a neuromuscular junction. Components of a Muscle Fiber Muscle fibers surrounded by connective tissue Sarcolemma = these nuclei lie immediately below the muscle fiber’s plasma membrane, muscle; repeats over and over Multinucleated because each muscle fiber’s formed during embryonic life from the fusion of several cells Sarcoplasm = semifluid cytoplasm, muscle Components of a Muscle Fiber Contains many myofibrils-contains the fibers contractile machinery, made up of orderly repeating structures Sarcoplasmic reticulum = smooth ER-holds calcium (secrestored in SR); sac-like membranous network which surrounds each myofibril; function: store calcium ions and to release them into the cytosol when the muscle cell is stimulated to contract, calcium is released in response to electrical signals that travel from the sarcolemma to the t- tubules and they serve as chemical messangers that carry these signals to the cell’s interior where the myofibrils are located Contains many mitochondria- high energy Transverse tubules = T tubules ; SR closely associated with these structures, connected to the sacrolemma and penetrate into the cell’s interior SR and t-tubules play an important role in the activation of muscle contraction because they help transmit signals from the sarcolemma to the myofibrils enabling a muscle cell to respond to neural input
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This note was uploaded on 06/25/2008 for the course BIOL 2160 taught by Professor Kt during the Spring '08 term at LSU.

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biol 2160-exam 3 - Chapter 12. Muscle Physiology Be sure...

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