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Muscle Physiology

Muscle Physiology. Human Anatomy and Physiology II Oklahoma City Community College. Dennis Anderson. Muscle Tissue. Skeletal Muscle Cardiac Muscle Smooth Muscle. Skeletal Muscle. Long cylindrical cells Many nuclei per cell Striated Voluntary Rapid contractions. Cardiac Muscle.

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Muscle Physiology

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  1. Muscle Physiology Human Anatomy and Physiology II Oklahoma City Community College Dennis Anderson

  2. Muscle Tissue • Skeletal Muscle • Cardiac Muscle • Smooth Muscle

  3. Skeletal Muscle • Long cylindrical cells • Many nuclei per cell • Striated • Voluntary • Rapid contractions

  4. Cardiac Muscle • Branching cells • One or two nuclei per cell • Striated • Involuntary • Medium speed contractions

  5. Smooth Muscle • Fusiform cells • One nucleus per cell • Nonstriated • Involuntary • Slow, wave-like contractions

  6. Microanatomy of Skeletal Muscle

  7. Z line Z line

  8. H Band

  9. Sarcomere Relaxed

  10. Sarcomere Partially Contracted

  11. Sarcomere Completely Contracted

  12. Tropomyosin Binding Site Troponin

  13. Myosin

  14. Neuromuscular Junction

  15. Acetylcholine Opens Na+ Channel

  16. Muscle Contraction Summary • Nerve impulse reaches myoneural junction • Acetylcholine is released from motor neuron • Ach binds with receptors in the muscle membrane to allow sodium to enter • Sodium influx will generate an action potential in the sarcolemma

  17. Muscle Contraction Continued • Action potential travels down T tubule • Sarcoplamic reticulum releases calcium • Calcium binds with troponin to move the troponin, tropomyosin complex • Binding sites in the actin filament are exposed

  18. Muscle Contraction Continued • Myosin head attach to binding sites and create a power stroke • ATP detaches myosin heads and energizes them for another contaction • When action potentials cease the muscle stop contracting

  19. Motor UnitAll the muscle cells controlled by one nerve cell

  20. Motor Unit Ratios • Back muscles • 1:100 • Finger muscles • 1:10 • Eye muscles • 1:1

  21. ATP

  22. Creatine + ATP Creatine phosphate + ADP Creatine • Molecule capable of storing ATP energy

  23. Creatine + ATP Creatine Phosphate • Molecule with stored ATP energy Creatine phosphate+ ADP

  24. Muscle Fatique • Lack of oxygen causes ATP deficit • Lactic acid builds up from anaerobic respiration

  25. Muscle Atrophy • Weakening and shrinking of a muscle • May be caused • Immobilization • Loss of neural stimulation

  26. Muscle Hypertrophy • Enlargement of a muscle • More capillaries • More mitochondria • Caused by • Strenuous exercise • Steroid hormones

  27. Steroid Hormones • Stimulate muscle growth and hypertrophy

  28. Muscle Tonus • Tightness of a muscle • Some fibers always contracted

  29. Tetany • Sustained contraction of a muscle • Result of a rapid succession of nerve impulses

  30. Tetanus

  31. Refractory Period • Brief period of time in which muscle cells will not respond to a stimulus

  32. Refractory

  33. Refractory Periods Skeletal Muscle Cardiac Muscle

  34. Isometric Contraction • Produces no movement • Used in • Standing • Sitting • Posture

  35. Isotonic Contraction • Produces movement • Used in • Walking • Moving any part of the body

  36. THE END

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