1. Chapter 8 The Nervous System

2. Organization of nervous system Central Nervous System Central Nervous System Peripheral Nervous System Peripheral Nervous System

3. Integration of CNS and PNS

4. The Neuron is the Functional unit of the nervous system Functional unit of the nervous system

5. The “model” neuron

7. Peripheral Nervous System

8. Afferent Neurons Sensory Receptors send information to CNS Sensory Receptors send information to CNS

9. Efferent Neurons Carry information to effector cells of the body Carry information to effector cells of the body

10. PNS is divided into 1. Autonomic Division 1. Autonomic Division –Sympathetic branch –Parasysmpathetic branch

11. PNS is divided into 2. Somatic Motor division 2. Somatic Motor division –Controls skeletal muscle

12. PNS divided into 3. Enteric division 3. Enteric division

13. Glial cells of the PNS Schwann Cells Schwann Cells Satellite Cells Satellite Cells

14. The PNS and Schwann Cell

15. Nodes of Ranvier: Are not covered by myelin

16. Central Nervous System

17. Glial cells of CNS Astrocytes Astrocytes –Nutrition Ependymal Ependymal –barrier Microgilia Microgilia –Immune Oligodendrocytes Oligodendrocytes –Myelin

18. An overview of glial cells

19. Remember the neuron… Communicates information throughout the body, but how? Communicates information throughout the body, but how?

20. Another picture of vertebrate neuron

21. By Action Potentials!

22. Action Potentials are our nerve impulses. It’s all to do with communication.

23. We can look at an action potential as an electrical event.

24. First we remember how ions influence the membrane potential (Em) of a cell.

25. K+ Large non-diffusible anionic proteins Is the charge across this cell zero? K+ Chemical gradient Electrical Force Permeable only to K+ Volt meter

26. No! It is –90 mV! Why?

27. Now let’s try to think about a living excitable cell…

28. Resting Neuron Membrane Potential Volt meter

29. Now what does the volt meter read?

30. -70 mV at rest but the Em can change when a nerve is “excited”.

31. But why do we care about these values?

32. A change in Em results in NT release!

33. But how does this change in charge occur so that the neurotransmitter can be released?

34. A simple flow chart of electrical events Graded potentials Graded potentials Action potentials Action potentials Neurotransmitter release Neurotransmitter release

35. Graded potentials decrease in strength as they spread out from the point of origin but may bring about an action potential.

37. The end of Part 1