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Neuromuscular Fundamentals

Neuromuscular Fundamentals. Anatomy and Kinesiology 420:024. Outline. Introduction Structure and Function Fiber Arrangement Muscle Actions Role of Muscles Neural Control Factors that Affect Muscle Tension. Introduction. Responsible for movement of body and all of its joints

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Neuromuscular Fundamentals

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  1. Neuromuscular Fundamentals Anatomy and Kinesiology 420:024

  2. Outline • Introduction • Structure and Function • Fiber Arrangement • Muscle Actions • Role of Muscles • Neural Control • Factors that Affect Muscle Tension

  3. Introduction • Responsible for movement of body and all of its joints • Muscles also provide: • Over 600 skeletal muscles comprise approximately 40 to 50% of body weight • 215 pairs of skeletal muscles usually work in cooperation with each other to perform opposite actions at the joints which they cross • Aggregate muscle action:

  4. Muscle Tissue Properties • Irritability or Excitability • Contractility • Extensibility • Elasticity

  5. Outline • Introduction • Structure and Function • Fiber Arrangement • Muscle Actions • Role of Muscles • Neural Control • Factors that Affect Muscle Tension

  6. Structure and Function • Nervous system structure • Muscular system structure • Neuromuscular function

  7. Figure 14.1, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings.

  8. Nervous System Structure • Integration of information from millions of sensory neurons  action via motor neurons Figure 12.1, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings.

  9. Nervous System Structure • Organization • Brain • Spinal cord • Nerves • Fascicles • Neurons Figure 12.2, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings. Figure 12.7, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings.

  10. Nervous System Structure • Both sensory and motor neurons in nerves Figure 12.11, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings.

  11. Nervous System Structure • The neuron: Functional unit of nervous tissue (brain, spinal cord, nerves) • Dendrites: • Cell body: • Axon: • Myelin sheath: • Nodes of Ranvier: • Terminal branches: • Axon terminals: • Synaptic vescicles: • Neurotransmitter:

  12. Dendrites Cell body Axon Myelin sheath Node of Ranvier Terminal ending Terminal branch Figure 12.4, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings.

  13. Figure 12.8, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings. Terminal ending Synaptic vescicle Neurotransmitter: Acetylcholine (ACh)

  14. Figure 12.19, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings.

  15. Structure and Function • Nervous system structure • Muscular system structure • Neuromuscular function

  16. Classification of Muscle Tissue • Three types: 1. Smooth muscle 2. Cardiac muscle 3. Skeletal muscle

  17. Muscular System Structure • Organization: • Muscle (epimyseum) • Fascicle (perimyseum) • Muscle fiber (endomyseum) • Myofibril • Myofilament • Actin and myosin • Other Significant Structures: • Sarcolemma • Transverse tubule • Sarcoplasmic reticulum • Tropomyosin • Troponin

  18. Figure 10.1, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings.

  19. Figure 10.4, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings.

  20. http://staff.fcps.net/cverdecc/Adv%20A&P/Notes/Muscle%20Unit/sliding%20filament%20theory/slidin16.jpghttp://staff.fcps.net/cverdecc/Adv%20A&P/Notes/Muscle%20Unit/sliding%20filament%20theory/slidin16.jpg

  21. Figure 10.8, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings.

  22. Structure and Function • Nervous system structure • Muscular system structure • Neuromuscular function

  23. Neuromuscular Function • Basic Progression: 1. Nerve impulse 2. Neurotransmitter release 3. Action potential along sarcolemma 4. Calcium release 5. Coupling of actin and myosin 6. Sliding filaments

  24. Nerve Impulse • What is a nerve impulse? -Transmitted electrical charge -Excites or inhibits an action -An impulse that travels along an axon is an ACTION POTENTIAL

  25. Nerve Impulse • How does a neuron send an impulse? -Adequate stimulus from dendrite -Depolarization of the resting membrane potential -Repolarization of the resting membrane potential -Propagation

  26. Nerve Impulse • What is the resting membrane potential? -Difference in charge between inside/outside of the neuron -70 mV Figure 12.9, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings.

  27. Nerve Impulse • What is depolarization? -Reversal of the RMP from –70 mV to +30mV Propagation of the action potential Figure 12.9, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings.

  28. Nerve Impulse • What is repolarization? -Return of the RMP to –70 mV Figure 12.9, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings.

  29. +30 mV -70 mV

  30. Neuromuscular Function • Basic Progression: 1. Nerve impulse 2. Neurotransmitter release 3. Action potential along sarcolemma 4. Calcium release 5. Coupling of actin and myosin 6. Sliding filaments

  31. Release of the Neurotransmitter • Action potential  axon terminals 1. Calcium uptake 2. Release of synaptic vescicles (ACh) 3. Vescicles release ACh 4. ACh binds sarcolemma

  32. Figure 12.8, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings. Ca2+ ACh

  33. Figure 14.5, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings.

  34. Neuromuscular Function 1. Nerve impulse 2. Neurotransmitter release 3. Action potential along sarcolemma 4. Calcium release 5. Coupling of actin and myosin 6. Sliding filaments

  35. Ach

  36. AP Along the Sarcolemma • Action potential  Transverse tubules 1. T-tubules carry AP inside 2. AP activates sarcoplasmic reticulum

  37. Figure 14.5, Marieb & Mallett (2003). Human Anatomy. Benjamin Cummings.

  38. Neuromuscular Function 1. Nerve impulse 2. Neurotransmitter release 3. Action potential along sarcolemma 4. Calcium release 5. Coupling of actin and myosin 6. Sliding Filaments

  39. Calcium Release • AP  T-tubules  Sarcoplasmic reticulum 1. Activation of SR 2. Calcium released into sarcoplasm

  40. CALCIUM RELEASE Sarcolemma

  41. Neuromuscular Function 1. Nerve impulse 2. Neurotransmitter release 3. Action potential along sarcolemma 4. Calcium release 5. Coupling of actin and myosin 6. Sliding filaments

  42. Coupling of Actin and Myosin • Tropomyosin • Troponin

  43. Blocked Coupling of actin and myosin

  44. Neuromuscular Function 1. Nerve impulse 2. Neurotransmitter release 3. Action potential along sarcolemma 4. Calcium release 5. Coupling of actin and myosin 6. Sliding filaments

  45. Sliding Filament Theory • Basic Progression of Events 1. Cross-bridge 2. Power stroke 3. Dissociation 4. Reactivation of myosin

  46. Cross-Bridge • Activation of myosin via ATP -ATP  ADP + Pi + Energy -Activation  “cocked” position

  47. Power Stroke • ADP + Pi are released • Configurational change • Actin and myosin slide

  48. Dissociation • New ATP binds to myosin • Dissociation occurs

  49. Reactivation of Myosin Head • ATP  ADP + Pi + Energy • Reactivates the myosin head • Process starts over • Process continues until: -Nerve impulse stops -AP stops -Calcium pumped back into SR -Tropomyosin/troponin back to original position

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