Chapter 3: The Neuronal Membrane at Rest

1. Neuroscience Chapter 3: The Neuronal Membrane at Rest 高毓儒 Institute of Physiology, School of Medicine National Yang-Ming University 2826-7086 yrkou@ym.edu.tw

2. Outline • Introduction • The Cast of Chemicals • The Movement of Ions • The Ionic Basis of the Resting Membrane Potential • Review

3. What we are? Introduction

4. Example-A Simple Reflex Introduction (BF3.1)

5. A Simplified Structure Introduction

6. Structure and Function Introduction Cognition and Behavior The Nervous System Collection, Distribution and Integration The Neuron Excitation

7. A Simplified Function Introduction Encoding by Frequency and Pattern Conduction Action Potential Resting Membrane Potential

8. Analogy Introduction Light or Heat Conduction Electricity Generator Differences

9. Important Elements The Beauty • Ions • Bilayer membrane • Differential permeability to ions • Channels and pumps • Differential responses

10. Water and Ions The Cast of Chemicals • Cations and anions • Monovalient and divalent • Na , K , Ca , Cl + - + 2+

11. Phospholipid Membrane The Cast of Chemicals • Phospholipid bilayer • Hydrophilic and hydrophobic

12. Channel Protein The Cast of Chemicals • Ion channels and ion pumps

13. Protein The Cast of Chemicals • Amino acids and polypeptides

14. Diffusion The Movement of Ions • Concentration gradient

15. Electrical Current The Movement of Ions • Ohm’s law: I = gV • g: conductance • I: currect • V: potential

16. Electrical Current The Movement of Ions • g = 0 • g > 0

17. Measurement Resting Membrane Potential

18. Equilibrium Potential Resting Membrane Potential

19. Equilibrium Potential Resting Membrane Potential Minuscule changes in ionic concentration 100 mM 99.99999 mM Large changes in membrane potential 0 mV 80 mV

20. Equilibrium Potential Resting Membrane Potential • The difference occurs only at the inside and outside surface. • Vm – Eion = ionic driving force

21. Equilibrium Potential Resting Membrane Potential + • Another example: Na

22. Equilibrium Potential Resting Membrane Potential • The Nernst equation

23. Ionic Distributions Resting Membrane Potential

24. Ionic Distributions Resting Membrane Potential + + • Role of Na -K pump – an electrogenic pump

25. Ionic Distributions Resting Membrane Potential 2+ • Role of Ca pump

26. Ionic Permeabilities Resting Membrane Potential + + • Na and K - equilibrium potential • PNa < 40 X PK • The Goldman equation + +

27. Potassium Channels Resting Membrane Potential • Structure

28. Potassium Channels Resting Membrane Potential + • Effect of external K concentration • Deporlarization

29. Potassium Channels Resting Membrane Potential + • Protection by blood-brain barrier • Protection by astrocytes via spatial buffering

30. Sodium Channels Resting Membrane Potential + • Effect of external Na concentration

31. Review Resting Membrane Potential • What two functions do proteins in the neuronal membrane perform to establish and maintain the resting membrane potential? • On which side of the neuronal membrane are Na ions more abundant? • When the membrane is at the K equilibrium potential, in which direction (in or out) is there a net movement of K ? + + +

32. Review Resting Membrane Potential • There is a much greater K concentration inside the cell than outside. Why, then , is the resting membrane potential negative? • When the brain is deprived of oxygen, the mitochondia within neurons cease producing ATP. What effect would this have on the resting membrane potential? +

33. Neuroscience Chapter 4: The Action Potential 高毓儒 Institute of Physiology, School of Medicine National Yang-Ming University 2826-7086 yrkou@ym.edu.tw

34. Outline • Introduction • Properties of the action potential • The action potential – in theory • The action potential – in reality • Action potential conduction • Action potential, axons, and dendrites • Review

35. Action Potential Introduction • Action potential vs. electricity • Electrical charge of ions vs. generator • Non-degraded vs. degraded conduction • All-or-none vs. adjustable characteristic • Encoding by frequency and pattern vs. magnitude of electrical power

36. Measurement AP-Properties

37. The Up and Down AP-Properties

38. Generation AP-Properties

39. Generation AP-Properties • Concept of threshold • Concept of all-or-none

40. Generation AP-Properties • Absolute refractory period • Relative refractory period

41. Current and Conductance AP-in Theory • A simplified model at resting state (0 - 80 mV)

42. Current and Conductance AP-in Theory • A simplified model - upon stimulation (-80 – 62 mV)

43. Current and Conductance AP-in Theory • A simplified model upon stimulation (62 - -80 mV)

44. + Voltage-Gated Na Channel AP-in Reality • Structure – 4 domains

45. + Voltage-Gated Na Channel AP-in Reality • Structure – 6 helices for each domain

46. + Voltage-Gated Na Channel AP-in Reality • Structure – domains for specificities

47. + Voltage-Gated Na Channel AP-in Reality • Depolarization and pore opening

48. + Voltage-Gated Na Channel AP-in Reality • Pore selectivity

49. + Voltage-Gated Na Channel AP-in Reality • Patch-clamp technique

50. + Voltage-Gated Na Channel AP-in Reality • Functional properties