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B17 ns03part1

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Lesson on Nervous System

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B17 ns03part1

  1. 1. Nervous System Part 1 Chapter 17
  2. 2. Nervous System Control System
  3. 3. Also aCommunication System3/24/2011 NS 3
  4. 4. Pattern Of Control stimulus - response input - integration - output3/24/2011 NS 4
  5. 5. Pattern Of Control stimulus response input - integration - output3/24/2011 NS 5
  6. 6. 3/24/2011 NS 6
  7. 7. Neurons • the nervous system is made up of two types of cells: • neurons - irritable (responsive), conductive • glial cells - protective, supportive & nourishing3/24/2011 NS 7
  8. 8. Neuron Structure3 main parts:• dendrites - receiving area• cell body - integrating area• axon & terminals - sending area3/24/2011 NS 8
  9. 9. Neuron Structure3/24/2011 NS 9
  10. 10. Neuron Structure• the nerve impulse or action potential is the information sent from one nerve to another• it travels from the dendrites to cell body to axon 3/24/2011 NS 10
  11. 11. Neuron Structure• some neurons are “myelinated” and some are not (unmyelinated)• myelinated neurons have a fatty myelin sheath around the axon3/24/2011 NS 11
  12. 12. Neuron Structure• myelinated axon• myelin sheath• node of Ranvier3/24/2011 NS 12
  13. 13. Myelin Sheath3/24/2011 NS 13
  14. 14. Classes Of Neuronssensory (afferent) -carry informationfrom sense organs(eyes, ears) to CNS 3/24/2011 NS 14
  15. 15. 3/24/2011 NS 15
  16. 16. Classes Of Neuronse.g. optic nerve auditory nerve neurons carrying temperature & pain sensations• short axons• long dendrites 3/24/2011 NS 16
  17. 17. Classes Of Neurons• interneurons (association) carry information between other neurons inside the CNS they often form tracts 3/24/2011 NS 17
  18. 18. Classes Of Neuronse.g. corpus callosum, spinal cord tracts• short dendrites• long or short axons3/24/2011 NS 18
  19. 19. Classes Of Neurons• motor neurons (efferent) carry information from the CNS to the effector organs (muscles & glands)3/24/2011 NS 19
  20. 20. Classes Of Neuronse.g. nerves to skeletal muscles, viscera & glands• short dendrites• long axons3/24/2011 NS 20
  21. 21. Impulse Or Action Potential• neurons carry information• neurons are arranged in pathways• impulses travel along the pathways from one neuron to another neuron 3/24/2011 NS 21
  22. 22. 3/24/2011 NS 22
  23. 23. 3/24/2011 NS 23
  24. 24. Resting Membrane Potential• electrical event• difference in charge across the resting cell axon membrane (- 60 to -70mv inside)3/24/2011 NS 24
  25. 25. Resting Membrane Potential3/24/2011 NS 25
  26. 26. Resting Membrane Potential• +ve sodium ions outside• +ve potassium & -ve proteins inside 3/24/2011 NS 26
  27. 27. Resting Membrane Potential• Na/K pump keeps ion balance 3/24/2011 NS 27
  28. 28. Resting Membrane Potential3/24/2011 NS 28
  29. 29. Ion Movements Across Resting Neuron Membrane3/24/2011 NS 29
  30. 30. Action Potential• stimulus to nerve causes• an electrical change which travels down the axon due to• Na+ moving in then• K+ moving out 3/24/2011 NS 30
  31. 31. Action Potential• Depolarization – change in charge across neuron membrane from –60 mv to + 40 mv inside• Repolarization – restoration of membrane back to resting level of – 60 mv inside• Threshold Potential – level of depolarization that must be reached to trigger an action potential3/24/2011 NS 31
  32. 32. Action Potential 43/24/2011 NS 32
  33. 33. Resting Membrane Potential3/24/2011 NS 33
  34. 34. Depolarization Begins3/24/2011 NS 34
  35. 35. Depolarization Ends Repolarization Begins3/24/2011 NS 35
  36. 36. Repolarization Complete3/24/2011 NS 36
  37. 37. Action Potential• Action Potential3/24/2011 NS 37
  38. 38. Action Potential3/24/2011 NS 38
  39. 39. Action Potential2 parts: upswing down swing depolarization repolarization 3/24/2011 NS 39
  40. 40. Action Potential2 parts: upswing down swing Na+ inflow K+ outflow depolarization repolarization 3/24/2011 NS 40
  41. 41. Action Potential• Na+/K+ pump in membrane• pumps the Na+ out & the• K+ in after the action potential is over 3/24/2011 NS 41
  42. 42. Action Potential• the depolarization at one point of the membrane acts as a• stimulus for the next point on the membrane which then depolarizes and so on down the membrane 3/24/2011 NS 42
  43. 43. Refractory Period• the period following one stimulus when the neuron cannot respond to another stimulus• so each action potential is a separate event3/24/2011 NS 43
  44. 44. Action Potential• the action potential is ALL OR NONE - it either happens fully or not at all- it cannot be partial 3/24/2011 NS 44
  45. 45. Nerve Conduction Speed• larger, myelinated axons conduct faster by• “saltatory conduction” where action potential jumps from node to node3/24/2011 NS 45
  46. 46. Saltatory Conduction3/24/2011 NS 46
  47. 47. Synapse • information passes from one neuron to another • across synapses using • chemical transmitters • synapses are one way only3/24/2011 NS 47
  48. 48. Synapse • a synapse can be between • 2 neurons or between a • neuron & its effector organ • it is at synapses that mood altering drugs affect the nervous system3/24/2011 NS 48
  49. 49. Synapse• neuron - neuron synapse• axon terminal 3/24/2011 NS 49
  50. 50. 3/24/2011 NS 50
  51. 51. Summation & Integration• all sensory input to the neuron cell body at any time is added together or “summated”• if there is enough stimulation an action potential will be triggered 3/24/2011 NS 51
  52. 52. Neurotransmitters• acetyl choline (ACh) - destroyed by cholinesterase• nor-adrenaline (nor- epinephrine) - destroyed by monoamine oxidase (MAO) 3/24/2011 NS 52
  53. 53. Neurotransmitters3/24/2011 NS 53
  54. 54. Neurotransmitters• low nor- epinephrine (adrenaline) levels• are linked with 3/24/2011 NS 54
  55. 55. Neurotransmitters • can be excitatory e.g. ACh, norepinephrine, serotonin or inhibitory e.g. GABA & glycine3/24/2011 NS 55
  56. 56. Neurotransmitters• there are also naturally occurring• painkillers or opiates - such as those which give a “runner’s high”3/24/2011 NS 56
  57. 57. Nervous System - Structure2 regions:• central nervous system - brain & spinal cord• peripheral nervous system - everything else….. 3/24/2011 NS 57
  58. 58. Organization Of The Nervous SystemCNS PNSbrain cranial nerves* (12 pairs)spinal spinal nerves*cord (31 pairs) * and associated ganglia3/24/2011 NS 58
  59. 59. Ganglia & NucleiCollections of neuron cell bodies in the:• CNS - nuclei (gray matter) 3/24/2011 NS 59
  60. 60. Ganglia & Nuclei• PNS - ganglia (spinal ganglia & autonomic ganglia) 3/24/2011 NS 60
  61. 61. Spinal Cord• central canal filled with CSF• outer white matter - myelinated tracts• inner gray matter - cell bodies & unmyelinated tracts 3/24/2011 NS 61
  62. 62. Spinal Cord Functions• reflex centre part of the spinal reflex arc• communication between the brain & the peripheral nervous system (many tracts )3/24/2011 NS 62
  63. 63. Spinal Cord • spinal reflex dorsal root ventral root interneuron3/24/2011 NS 63
  64. 64. Brain• ventricles• white matter (tracts)• gray matter ( nuclei & tracts)• different functions in different areas3/24/2011 NS 64
  65. 65. Brain - Cerebrum Prefrontal lobe3/24/2011 NS 65
  66. 66. Brain3/24/2011 NS 66
  67. 67. Brain & Spinal Cord• hollow - filled with cerebrospinal fluid (CSF)• covered with 3 membranes –• meninges• both are protective & supportive 3/24/2011 NS 67
  68. 68. Parts Of The Brain (from highest to lowest)• cerebral hemispheres (4 lobes)• diencephalon (thalamus/hypothalamus)• limbic system• cerebellum 3/24/2011 NS 68
  69. 69. Parts Of The Brain (from highest to lowest)brain stem• midbrain• pons• medulla oblongata• reticular formation (in brain stem) 3/24/2011 NS 69
  70. 70. Structure Of Cerebrum• 2 hemispheres joined by the corpus callosum• basal ganglia help control skeletal muscles 3/24/2011 NS 70
  71. 71. Structure Of Cerebrum4 lobes1) frontal2) parietal3) temporal4) occipital3/24/2011 NS 71
  72. 72. Brain Functions 4 lobes3/24/2011 NS 72
  73. 73. Cerebral Cortex• outer layer of the cerebrum = the cortex• gray matter• motor, sensory and association areas3/24/2011 NS 73
  74. 74. Cerebral Cortex3/24/2011 NS 74
  75. 75. Brain Functions1) frontal - motor control & highest mental functions2) parietal - skin sensese.g. pain, touch, temperature3/24/2011 NS 75
  76. 76. Brain Functions3) temporal - sound & smell, sensory interpretation4) occipital - sight 3/24/2011 NS 76
  77. 77. Brain FunctionsCerebrum (cerebral hemispheres)• highest functionse.g. memory, learning, perception, awareness3/24/2011 NS 77
  78. 78. Brain FunctionsDiencephalon• thalamus - sensory filter• hypothalamus - homeostasis (many functions) e.g. hunger, body temperature 3/24/2011 NS 78
  79. 79. Brain FunctionsCerebellum• balance , posture3/24/2011 NS 79
  80. 80. Brain FunctionsBrain Stem – sensory & motor tracts, reticular formation• midbrain - nuclei e.g. (balance)• pons - respiratory centres• medulla - vital centres 3/24/2011 NS 80
  81. 81. Brain Functions• reticular formation network which contains the• Reticular Activating System which controls alertness/sleep3/24/2011 NS 81
  82. 82. Chapter 17: Part 1 Internet Resources:• http://yucky.kids.discovery.com/noflash/body/ pg000136.html• http://users.tpg.com.au/users/amcgann/body/ nervous.html• http://faculty.washington.edu/chudler/introb.ht ml• http://users.rcn.com/jkimball.ma.ultranet/Biolo gyPages/C/CNS.html• http://www.bartleby.com/107/183.html3/24/2011 NS 82

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