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Muscular System

Muscular System. Muscle tissue is made of…. Myocytes -elongated cells Also called muscle fibers Myotcytes are closely associated with neurons. Myocytes are mutlinucleated. What does striated mean?. Striped or having bands Due to proteins.

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Muscular System

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  1. Muscular System

  2. Muscle tissue is made of… • Myocytes-elongated cells • Also called muscle fibers • Myotcytes are closely associated with neurons

  3. Myocytes are mutlinucleated

  4. What does striated mean? • Striped or having bands • Due to proteins

  5. Identify the type(s) of muscle tissue being described • Involuntary • Striped appearance • Coordinated activity to act as a pump • Moves bones and the facial skin • Referred to as muscular system • voluntary

  6. Skeletal Muscle • General Components: • Skeletal/striated muscle tissue • Nervous tissue • Blood • Connective tissue

  7. Cells of muscle tissue = myocytes • Fascicle=group of myocytes • Perimysium= connective tissue that wraps each fascicle • Endomysium= connective tissue between myocytes

  8. Epimysium = connective tissue that wraps a group of fasicles

  9. Parts of individual fiber/cell

  10. Sarco = flesh; Myo = muscle • Membrane = sarcolema • Cytoplasm = sarcoplasm • Endoplasmic reticulum (full of calcium ions) = sarcoplasmic reticulum • Myofibrils = threadlike structures of actin and myosin

  11. Myofibrils are composed of sarcomeres

  12. Muscle Contraction • http://www.youtube.com/watch?v=0kFmbrRJq4w

  13. Step 1 • Nervous impulse sent from the central nervous system stimulates motor neuron to release acetylcholine into synaptic cleft

  14. Step 2 • Acetylcholine diffuses through synaptic cleft and binds to receptor on muscle fiber sarcolemma (cell membrane)

  15. Step 3 • Signal reaches sarcoplasmic reticulum and makes its membrane more permeable to Ca2+, so Ca2+ moves out into sarcoplasm

  16. Step 4 • Ca2+ will move to sarcomere and bind to thin filaments, exposing myosin-binding sites of actin’s surface

  17. Step 5 • Cross-bridge forms between actin and myosin

  18. Step 6 • Cross-bridge pulls actin filament which requires the release of ADP and phosphate

  19. Step 6 • New ATP binds to myosin, causing linkage release

  20. Step 6 • Hydrolysis of ATP to ADP and phosphate allows myosin to assume position to bind to next site on actin filament

  21. Muscle Relaxation • Acetylcholine does not bind to muscle fiber receptors, but is broken down in synaptic cleft • S.R. moves Ca2+ back inside, causes myosin-binding site to close • Sarcomere lengthens/relaxes • This also requires ATP

  22. Muscles get energy from ATP and creatine phosphate.

  23. The energy is generated through cellular respiration, which requires oxygen

  24. Oxygen is transported through muscle cells by myoglobin.

  25. Muscles will utilize fermentation for energy production when oxygen is not available  lactic acid build up.

  26. Lactic acid is broken down in the liver, but his process requires oxygen

  27. When you are exercising, you can enter oxygen debt

  28. What is muscle fatigue? • Inability to contract muscles after persistent and prolonged use. • Most common cause = lactic acid build-up

  29. http://www.youtube.com/watch?v=LKhkvSRQZYo

  30. Origin and Insertion

  31. Movement usually requires multiple muscles • Prime mover (agonist) = muscle primarily responsible for movement • Synergists = muscles that contract and assist the prime mover • Antagonists = resist the prime mover’s action and cause movement in the opposite direction

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