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Review: Neural Communication

Review: Neural Communication. Resting Cell Charges. KW 4-10. Depolarization. A Graded Potential. KW 4-11. Hyperpolarization. KW 4-11. A Graded Potential. Phases of the action potential. K&W 4-14. Cell body end of axon. Direction of neural impulse: toward axon terminals.

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Review: Neural Communication

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  1. Review:Neural Communication

  2. Resting Cell Charges KW 4-10

  3. Depolarization A Graded Potential KW 4-11

  4. Hyperpolarization KW 4-11 A Graded Potential

  5. Phases of the action potential K&W 4-14

  6. Cell body end of axon Direction of neural impulse: toward axon terminals Reversal of Charges

  7. Falling dominos K&W p. 131

  8. Ion flow K&W 4-15

  9. Properties of Action Potentials • All or none: fires completely or not at all • Self-propagates: recreates itself • Does not degrade: doesn’t lose power • Full strength to the end of axon • Axon can be any length

  10. Naked Neurons • Neurons without myelin sheath • Slower • Shorter • Can’t carry messages long distances • What does myelin sheath provide?

  11. Nodes of Ranvier K&W 4-16

  12. Saltatory conduction Saltare = to jump Action potential skips from node to node K&W 4-17

  13. Multiple Sclerosis • Jacqueline Du Pre • 1945-1987 • MS diagnosis in 1971 • Hilary and Jackie (1998 movie)

  14. Neuronal Integration • To fire or not to fire, that is the question • All or none principle: all or nothing at all • Why important?

  15. Firing Line

  16. Threshold

  17. Sherrington • Sir Charles Scott Sherrington • (1857-1952) • Withdrawal reflex • Principle of summation • Nobel prize in medicine 1932

  18. Withdrawal Reflex in Dogs • One mild pinch between toes  no response • Two pinches quickly in same spot  withdraw paw • Temporal Summation • Temporal = over time

  19. Paw reflex: part 2 • One mild pinch in one location  no response • Two pinches in different locations  withdraw paw • Spatial Summation • Spatial = over space

  20. Temporal: one location Postsynaptic cell motor Excitatory Postsynaptic Potential Presynaptic cell sensory KW 4-19 synapse

  21. Temporal EPSP KW 4-19 top

  22. Spatial: more than one location K&W 4-20

  23. Spatial EPSP KW 4-19

  24. Importance of EPSP • Excite cells • Bring about activity • Sensation felt • Muscle moved

  25. Excitation must be balanced • Nervous system can’t run on just excitation • Sometimes better not to respond • Role on inhibition • Calm down the nervous system

  26. Role of Inhibition • Provides break for the nervous system • Lowers activity levels • Keeps the brain from over-excitation, as in epilepsy

  27. EPSP and IPSP Inhibitory Postsynaptic Potential K&W 4-18

  28. Temporal IPSP KW 4-19

  29. TemporalCombos

  30. SpatialCombos

  31. A cell decides to fire Democracy of Cells K&W 4-21

  32. Autonomic nervous system controls physiological arousal Sympathetic division (arousing) Pupils dilate Decreases Perspires Increases Accelerates Inhibits Secrete stress hormones Parasympathetic division (calming) Pupils contract Increases Dries Decreases Slows Activates Decreases secretion of stress hormones EYES SALIVATION SKIN RESPIRATION HEART DIGESTION ADRENAL GLANDS Emotional Arousal

  33. Control over heart • Sympathetic  excites • Parasympathetic  inhibits • Work together to control heart

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