2. Review: Neural Communication

3. Resting Cell Charges KW 4-10

4. Depolarization KW 4-11 A Graded Potential

5. Hyperpolarization KW 4-11 A Graded Potential

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

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

8. Falling dominos K&W p. 131

9. Ion flow K&W 4-15

10. 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

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

12. Nodes of Ranvier K&W 4-16

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

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

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

16. Firing Line

17. Threshold

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

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

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

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

22. Temporal EPSP KW 4-19 top

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

24. Spatial EPSP KW 4-19

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

26. 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

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

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

29. Temporal IPSP KW 4-19

30. Temporal Combos

31. Spatial Combos

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

33. Emotional Arousal 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

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