Chapter 9 - Chapter 9 I. List the four functions of the...

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Chapter 9 I. List the four functions of the muscular system. II. Describe in detail the appearance of skeletal muscle and related structures. A. Connective Tissue Coverings 1. Fascia – sheet of fibrous connective tissue that encloses a muscle 2. Tendon – cordlike or bandlike mass of white fibrous connective tissue that connects a muscle to a bone a. projection from fascia 3. Aponeuroses – sheet of connective tissue that attaches muscles to fascia of adjacent muscles a. projection from fascia 4. Epimysium – layer of connective tissue that closely surrounds a skeletal muscle 5. Perimysium – extends inward from the epimysium and separates the muscle tissue into small sections 6. Fascicles – bundles of skeletal muscle fibers contained in sections of perimysium 7. Endomysium – sheath of connective tissue surrounding each skeletal muscle fiber B. Skeletal Muscle Fibers 1. Sarcolemma – cell membrane a. Transverse tubules (T - tubules) – membranous channel that extends inward from the sarcolemma and passes through the fiber 2. Sarcoplasm – cytoplasm of a muscle fiber a. Sarcoplasmic reticulum – membranous network of channels and tubules in a muscle fiber, corresponding to the endoplasmic reticulum of other cells i. surrounds each myofibril and runs parallel to it b. Cisternae – enlarged portion of the sarcoplasmic reticulum near the actin and myosin filaments of a muscle fiber i. single T-tubules run between 2 cisternae and form Triad 3. Myofibrils – abundant, parallel, threadlike structures a. contractile fibers in muscle cells b. Consist of 2 types of protein filaments i. Myosin – thick filaments of protein that, with actin, contracts and relaxes muscle fibers consists of two twisted protein strands with globular parts, cross-bridges (heads) , projecting
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Chapter 9 ii. Actin – thin filaments of protein in a muscle fiber that slide between filaments of the protein myosin, contracting muscle fibers thin filaments consist of double stands of actin twisted into a helix Troponin – protein that functions with tropomyosin to block muscle contraction until calcium ions are present three protein subunits attached to actin Tropomyosin – protein that block muscle contraction until calcium ions are present occupy the longitudinal grooves of the actin helix held in place by troponin molecule forming troponin-tropomyosin complex c. Sarcomere – structural and functional unit of a myofibril i. light and dark striations from myosin and actin form a repeating pattern of units extends from one Z line to the next ii. Striation pattern has 2 main parts I bands – light bands, composed of thin actin filaments Z lines – direct attachments that hold I bands together, appear in the center of I bands A bands – dark bands, composed of thick myosin filaments overlapping thin actin filaments H zone – lighter central region in A bands, consists of only thick filaments M line – thickening which consists of proteins that help hold the thick filaments in place Titin – protein that attaches myosin filaments to Z lines in muscle
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This note was uploaded on 01/14/2011 for the course BIO 142 taught by Professor Unknown during the Spring '10 term at Northern Virginia Community College.

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Chapter 9 - Chapter 9 I. List the four functions of the...

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