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Chapter 12

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Chapter 12

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  1. Chapter 12 Neural Tissue

  2. deals with information sense information process information respond to information

  3. PNS “nerves” cranial spinal Overview of classification: Anatomical CNS PNS “nerves” cranial spinal brain and spinal cord

  4. somatic autonomic Overview of classificaton: Functional: CNS afferent (carry to) efferent (bring out) sensory motor receptors

  5. cells: neurons processes soma fig. 12-1

  6. fig. 12-3

  7. fig. 12-2

  8. axonal transport material moving anterograde cell body synapse retrograde

  9. neural tissue neurons information neuroglia (glial cells) protection nourishment insulation modulation

  10. neural tissue neuroglia (CNS) ependymal cells astrocytesoligodendrocytes microglia

  11. neural tissue neuroglia (CNS) ependymal cells • line cavities of CNS • produce CSF • (cerebrospinal fluid)

  12. neural tissue neuroglia (CNS) ependymal cells astrocytes blood-brain barrier structural support nourish neurons

  13. neural tissue neuroglia neuroglia (CNS) ependymal cells astrocytesoligodendrocytes • wrap around axons • myelin

  14. neural tissue neuroglia (CNS) ependymal cells astrocytesoligodendrocytes microglia smallest clean up debris

  15. ependymal astrocytes oligodendrocytes microglia fig. 12-4

  16. neural tissue neuroglia (PNS) satellite cells like astrocytes in CNS Schwann cells like oligo’s in CNS

  17. fig. 12-5

  18. PNS fig. 12-6

  19. anatomy physiology how do the cells send information?

  20. cells: neurons processes synapses fig. 12-1

  21. 3 “potentials” fig. 12-7

  22. = / resting potential ICF ECF K+ proteins- Na+ Cl- +++++ -------

  23. chemical gradient ICF ECF K+ Na+

  24. electrical gradient ICF ECF K+ Na+ +++++ -------

  25. when at resting potential… fig 12-9a

  26. if membrane was freely permeable to potassium… fig 12-9b

  27. when at resting potential… fig 12-9c

  28. if membrane was freely permeable to sodium… fig 12-9d

  29. = / resting potential ICF ECF K+ Na+ +++++ -------

  30. membrane proteins and the distribution and movement of ions 1. leak channels 2. Na+/K+ pump 3. gated channels: a. chemically regulated channels b. voltage-regulated channels c. mechanically regulated channels 1. leak channels 2. Na+/K+ pump

  31. membrane proteins and the distribution and movement of ions leak channels K+ Na+ Na+/K+ pump ATP (active transport)

  32. Na+ leaks in K+ leaks out (always open) Na+/K+ pump (ATPase) pumps Na+ back out pumps K+ back in maintains resting potential = -70 mV

  33. oscilloscope

  34. oscilloscope millivolts 0 membrane is polarized resting potential -70 time --->

  35. membrane proteins and the distribution and movement of ions • potentials: • resting potential • graded potentials • action potentials

  36. membrane proteins and the distribution and movement of ions 1. leak channels 2. Na+/K+ pump 3. gated channels: a. chemically regulated channels b. voltage-regulated channels c. mechanically regulated channels

  37. a. chemically regulated channels • signal binds • (stimulus) • channel opens e.g., AChR fig. 12-10a

  38. b. voltage-regulated channels Na+ -70 mV closed -60 mV open 1/1000 sec +30 mV closed inactivated fig. 12-10b

  39. c. mechanically regulated channels closed mechanical stimulus- opens remove stimulus- closed fig. 12-10c

  40. membrane proteins and the distribution and movement of ions 1. leak channels 2. Na+/K+ pump 3. gated channels: a. chemically regulated channels b. voltage-regulated channels c. mechanically regulated channels

  41. membrane proteins and the distribution and movement of ions • potentials: • resting potential • graded potentials • action potentials fig. 12-7

  42. de repolarized Na+ in oscilloscope millivolts 0 polarized -70 time --->

  43. fig. 12-11

  44. fig. 12-11

  45. fig. 12-11

  46. fig 12-12

  47. graded potentials • local potentials • short range • only affect a • small portion of the cell • (may trigger “events” in other cells) action potentials a potential that is propagated along an axon (affects the whole cell)

  48. ? - a stimulus large enough to open • the Na voltage-gated channels “threshold” about -60 mV

  49. Na+ voltage-gated channel • normally closed (activation gate) • at resting potential most abundant in the membrane of the axon

  50. Na+ voltage-gated channel opens at -60mV lets Na+ in membrane depolarizes fig.12-10b