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MUSCLES

MUSCLES. 3 Types. Skeletal-striated/voluntary Smooth- involuntary Cardiac-heart, involuntary. Skeletal. Smooth. Cardiac. Skeletal Muscle Components. Skeletal muscle - numerous nuclei and mitochondria Fascia - dense CT, surrounds each muscle/separates

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MUSCLES

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  1. MUSCLES

  2. 3 Types • Skeletal-striated/voluntary • Smooth- involuntary • Cardiac-heart, involuntary

  3. Skeletal

  4. Smooth

  5. Cardiac

  6. Skeletal Muscle Components Skeletal muscle - numerous nuclei and mitochondria Fascia- dense CT, surrounds each muscle/separates - Tendon- cordlike, connects to bone - Aponeuroses- CT that connects bone - broad, fibrous sheets

  7. CT • Epimysium – outermost layer, surrounds entire muscle • Perimysium– separated and surrounds the FASCICLES -(bundles) of muscle fibers • Endomysium– surrounds each individual muscle fiber • Many layers= ability to move independently, allows blood vessels and nerves to pass through

  8. Draw

  9. Sarcolemma- muscle fiber membrane • Sarcoplasm- inner fluid, cytoplasm • Myofibrils- indiv muscle fibers made of myofilaments within the sarcoplasm

  10. Draw

  11. MYOFILAMENTS. two types: MYOSIN – thick filaments, two twisted proteins strands, globular parts (cross bridges) ACTIN – thin filaments, double strands in helix

  12. These filaments overlap to form dark and light bands on the muscle fiber • A band = dArk • thick (myosin) • I band = lIght • thIn (actin) • In the middle of each I band are Z lines. A sarcomere is one Z line to the other • arrangement of sarcomeres next to each other produces the STRIATIONS

  13. Sarcoplasmic Reticulum–network of membranous channels surrounding myofibril • Transverse tubules (T tubules) – extend from sacroplasmic reticulum into sacrolemma. • Cristernae- 2 tubes surrounding T tubes

  14. Hierarchy of muscle parts

  15. Muscles and Nervous System • Muscle contraction- movement of myofibrils: actin &myosin slide past one another, shortening sacromeres • Muscle fibers shortens - pulls attachments

  16. Neuron- • Axon- extends / capable of conducting nerve impulse • Motor Neuron- control skeletal muscles

  17. Synapse • Synapse- Space which info passes • Neurotransmitters- chemicals released into synapse • Neuromuscular junction- site where axon and muscle fiber meet- forms motor end plate • Nuceli/mitochondria abundant & sarcolemma is folded

  18. Synaptic cleft- separates neuron membrane and membrane of muscle fiber

  19. Steps for Contraction • Acetylcholine (Ach) –(neurotransmitter) released from end neuron • It diffuses across the gap to the muscle fiber • Muscle fiber is stimulated-impulse travels across fiber & into T tubules

  20. 4. Impulse reaches sarcoplasmic reticulum 5. Calcium ions are released 6. Cause linkages between actin and myosin 7. Actin filaments slide across the myosin 8. Muscle fiber shortens http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter42/animations.html#

  21. Sliding filament Theory The movement of the actin filaments over the myosin causes shortening of fiber

  22. http://entochem.tamu.edu/MuscleStrucContractswf/index.html

  23. Fiber Relaxation 1. Cholinesterase is released 2. Inhibits acetylcholine 3. No muscle stimulation 4. Calcium ions reabsorbed into S.R 5. Actin returns to normal position 6. Muscle fiber relaxes

  24. http://www.blackwellpublishing.com/matthews/myosin.html

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