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Fig. 7.1

Review:. Fig. 7.1. Functions of Skeletal Muscle:. Support the body (opposes the force of gravity) Make bones and other body parts move Maintain a constant body temperature Assist movement in cardiovascular and lymphatic vessels Protect internal organs and stabilize joints.

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Fig. 7.1

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  1. Review: Fig. 7.1

  2. Functions of Skeletal Muscle: • Support the body (opposes the force of gravity) • Make bones and other body parts move • Maintain a constant body temperature • Assist movement in cardiovascular and lymphatic vessels • Protect internal organs and stabilize joints

  3. Microscopic Anatomy of Skeletal Muscle: • What do we already know from histology? Striations. • Arrangement of myofilaments in a muscle fiber (cell). • Normal cell with some specialized terms for cell parts. (Plasma membrane = sarcolema, endoplasmic reticulum = sarcoplasmic reticulum)

  4. Microscopic Anatomy of Muscle (Sarcoplasmic Reticulum) • Remember this is the ER for muscle cells. • Sarcoplasmic reticulum has specialized pockets to store calcium ions (Ca2+) which is essential for muscle contraction. • The sarcoplasmic reticulum encases hundreds of myofibrils which allow for contraction of the muscle cell.

  5. Microscopic Anatomy of Muscle: • Myofibrils run the length of the muscle fiber. • Striations are formed by the placement of these myofibrils forming sarcomeres. • Sarcomeres contain two types of protein fibers: actin (thin and intertwined) and myosin (thick and shaped like golf club).

  6. Fig. 7.3a

  7. Fig. 7.3b

  8. Microscopic Anatomy of Muscle: • Sliding Filaments – when the muscles are triggered by motor nerve cells, impulses travel down the T-tubule of the sarcomere (see previous picture). Calcium is then released from the sarcoplasmic reticulum. This causes the sarcomere to shorten. The actin slides across the myosin. ATP provides the power for this contraction.

  9. Fig. 7.4

  10. Fig. 7.5

  11. Macroscopic Anatomy of Muscle: • 3 Layers of connective tissue are part of each muscle: Epimysium – surrounds entire muscle, dense layer of collagen fibers. Perimysium – divides muscle into compartments called fascicles. Endomysium – delicate connective tissue that surrounds each muscle cell or fiber. • Where these connective tissues run together at the end of muscles they form tendons or aponeurosis.

  12. Fig. 7.2a

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