Anatomy Chp 6 Notes Muscular System

Anatomy Chp 6 Notes Muscular System - Anatomy Chp 6 Notes...

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Anatomy Chp 6 Notes Muscular System I. Overview of Muscle Tissue A. The essential function of muscle is contraction B. Muscle Types 1. Skeletal, Cardiac and Smooth muscle have some things in common a. skeletal and smooth muscle cells are elongated and called muscle fibers b. muscle cells can shorten because of two types of myofilaments c. the prefixes myo, mys and sarco refer to muscle 2. Skeletal Muscle a. skeletal muscle fibers are packaged into organs called muscles b. attach to skeleton for movement c. Skeletal muscle fibers are cigar shaped, multinucleate cells, and are the largest fibers of the three types d. Striated muscle: fibers appear to be striped e. Voluntary Muscle: only muscle type subject to conscious control f. Endomysium: connective tissue that encloses each muscle fiber g. Perimysium: connective tissue that wraps several fibers into a bundle called a fascicle h. Epimysium: Many fascicles bound together by a tougher connective tissue covers the entire muscle i. Tendons: epimysium blend into a cordlike structure j. Aponeuroses: sheetlike tendon that attaches muscles indirectly to bones 3. Smooth Muscle
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a. no striations and is involuntary b. found mainly in the walls of visceral organs (Stomach etc) c. help to propel substances along d. have single nucleus, and are often arranged in layers e. smooth muscle contractions are slow and sustained 4. Cardiac Muscle a. found only in the heart b. striated and involuntary c. arranged in spiral or figure 8 shaped bundles d. cells are joined by special junctions called intercalated discs e. muscle fibers contract via a pace maker in the heart f. also can be controlled by the nervous system C. 4 Muscle Functions 1. Producing Movement: important in all functions of the body, also includes smooth muscle and visceral organs 2. Maintaining Posture: continuously make adjustments to keep proper posture 3. Stabilizing Joints: important during movement (shoulder) 4. Generating Heat: 75% of the ATP used to produce movement is lost as heat. a. Vital to maintaining constant body temp II. Microscopic Anatomy of Skeletal Muscle A. Multinucleate B. Sarcolemma: plasma membrane of muscle cells
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D. Myofibrils: long ribbonlike organelles that nearly fill the cytoplasm 1. I Bands: light color in myofibril 2. A Bands: dark color in myofibirl 3. I and A bands alternate giving the striated appearance 4. Z Disc: midline interruption of the I band 5. H Zone: lighter central area of the A Band 6. M Line: center of the H Zone E. Sarcomeres: chains of tiny contractile units aligned end to end along the length of the myofibril 1. the working part of the myofibril F. Myofiliaments: thread like protein structures in the sarcomeres 1. There are 2 types of myofilaments a. Thick Filaments: bundled molecules of a protein called myosin 1. also contain ATPase enzymes that split ATP to provide the power for contraction 2. Extend entire length of A band 3. center of thick filaments is smooth, but ends are studed 4. Cross Bridges:
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This note was uploaded on 11/22/2011 for the course BSC BSC1085 taught by Professor Sharonsimpson during the Fall '10 term at Broward College.

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Anatomy Chp 6 Notes Muscular System - Anatomy Chp 6 Notes...

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