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Muscle Physiology

Muscle Physiology. Human Anatomy and Physiology I Oklahoma City Community College. Dennis Anderson. Characteristics of Muscle Tissue. Excitability (Irritability) Contractility Extensibility Elasticity. Muscle Tissue. Skeletal Muscle Cardiac Muscle Smooth Muscle. Skeletal Muscle.

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Muscle Physiology

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

  2. Characteristics of Muscle Tissue • Excitability (Irritability) • Contractility • Extensibility • Elasticity

  3. Muscle Tissue • Skeletal Muscle • Cardiac Muscle • Smooth Muscle

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

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

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

  7. Muscle Stimulation Motor Neuron Muscle

  8. vesicle acetylcholine Motor Neuron

  9. Myoneural Junction muscle

  10. Acetylcholine Receptors Muscle membrane

  11. Acetylcholine Stimulates Muscle to Contract

  12. Acetylcholinesterase muscle Breaks Down Acetylcholine

  13. Damaged Neuron Acetylcholine not released Motor Neuron Muscle

  14. Skeletal Muscle

  15. Microanatomy of Skeletal Muscle

  16. Z line Z line

  17. H Band

  18. Sarcomere Relaxed

  19. Sarcomere Partially Contracted

  20. Sarcomere Completely Contracted

  21. Sarcomere I A I H Z Z

  22. Tropomyosin Binding Site Troponin

  23. Myosin

  24. Neuromuscular Junction

  25. Action Potential Voltage change in a neuron or muscle cell

  26. Acetylcholine Opens Na+ Channel

  27. 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

  28. 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

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

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

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

  32. ATP

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

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

  35. Myoglobin • Stores oxygen in muscle cells • Similar to hemoglobin in blood • Has higher affinity for oxygen than hemoglobin

  36. Hemoglobin Oxygen Myoglobin

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

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

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

  40. Steroid Hormones • Stimulate muscle growth and hypertrophy

  41. Anabolic Steroids • Decrease testosterone production • Testicular shrinkage • Infertility • Liver tumors • Prostate cancer • Heart disease • Stroke

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