Learning Objectives

1. Learning Objectives • Organization of the Nervous System • Electrical Signaling • Chemical Signaling • Networks of Neurons that Convey Sensation • Networks for Emotions & Behavior or Motor Systems

2. Evaluations: 5 Exams plus a Final Each exam including the final is worth 100 Points. The exams are multiple choice, matching,True/False. BRING TO EACH EXAM A 100 QUESTION SCANTRON. EXTRA CREDIT: Extra credit question (s) will only be available on Exam 5 and will be based on assigned outside reading listed above and will be worth 25 points. Grading: Total Possible Points 500 A= >90% B= >80% C= >70% Students with an “A” grade after 5 exams are exempt from the final. Students taking the final exam can drop the lowest grade on Exams 1-5 or a missed exam.

3. Policy on Grading • If you have a question about an incorrect answer, • Note it on your score sheet • At the end of the course if the points you think were mistakingly deducted would bring your grade up to the next letter grade, come see me then • If a question was universally missed by all I will consider giving you points for it.

4. Week 4 Tues 1-31 Electrical Signalling: Membrane Potential Thurs 2-2 Nernst & Goldman Equations Ch 3 Week 5 Tues 2-7 Action Potential Ch 4 Thurs 2-9 Ion Channels: Voltage Gated Week 6 Tues 2-13 Exam 2 Thurs Chapter 3 and 4 Matthew and ONLINE BEAR’S 3rd Edition Chapters

5. Electrical Properties of Neurons& Excitable Cells Resting Membrane Potential Equilibrium Potential of an Ion Nernst & Goldman Equations

10. Clinical significance of resting membrane potential • Jack Kevorkian kills patients with potassium sulfate • depolarizes cardiac and neuronal membranes • Die from heart failure, hearts stops beating because the resting membrane potential is not sufficiently negative

13. Generation of Vr • Selective permeability of neuron membrane • Unequal distribution of ions across membrane • Action of ion pumps • Largely due to potassium since no open channels for sodium • Slow leak for Na is rectified by the Na/K ATPase that pumps out 3 Na for 2 K

15. Plasma Membrane • Maintains the separation of ions and charges • Lipid bilayer is non polar and does not allow polar or charged molecules to cross • C. Ernest Overton: showed that non-polar molecules crossed PM but polar molecules did not.

16. Selective Permeability • The ability of membrane to select which ions or small particles can move through freely while restricting passage of others • Restriction is due to lipid bilayer • Selective passage is due to membrane proteins, selective ion channels and transporters, exchangers

17. Membrane Potential • The difference in charge across the plasma membrane. • Written as Vm • Generated by movement of ions across the membrane where the ionic concentrations of the intracellular and extracellular fluid are different • Inside the plasma membrane is always negative with respect to outside the plasma membrane at rest

18. Resting Membrane Potential • Membrane potential at which neuron membrane is at rest, ie does not fire action potential • Written as Vr

19. Ion Movement • Concentration gradient • Charge gradient • Together referred to as the electrochemical driving force • Action of ion pump

20. Electrochemical Gradient • Exerts force on ions and determines its movement • Based on concentration of ion inside/outside • Based on charge of the ion and charge of the pm • This determines the driving force on an ion in any instant of time

26. Equilibrium potential • Membrane Potential (potential difference across the plasma membrane) at which the net flow of an ion type = zero • The number of ions moving into the cell = the number of ions moving out of the cell for a particular species of ion

27. Equilibrium Potential of An Ion • The membrane potential at which the net driving force propelling the ion in = the net driving force proplling the ion out. • Written Eion; ENa, ECl, EK

31. Nernst Equation • Eion = 2.303 RT/zF log [ion]o/[ion]in • Eion = ionic equilibrium potential • Z= charge of ion • F= Faraday’s constant • T= absolute temperature at • R= gas constant • Simplifies to 58 mV

32. Nernst Equation Variables • Assumes that membrane is permeable to that ion • As temperature increases the diffusion increases • As charge on the molecule increases, it decreases the potential differences needed to balance diffusion forces.

33. ENa • Ena = 61.54mV log [Na]o/[Na]i • ECa = 30.77mV log [Ca]o/[Ca]i • CCl = -61.54mV log [Cl]o/[Cl]i

34. Resting Membrane Potential • Membrane potential at which neuron membrane is at rest, ie does not fire action potential • Written as Vr

35. Goldman Equation • Em= RT/F ln Pk[K]o+Pna[Na]o+PCl[Cl]i Pk[K]I+Pna[Na]I+PCl[Cl]o Also known as the constant field equation because it assumes that electrical field of the membrane potential is equal across the span of the membrane

36. Membrane Permeability • Membrane is 50 more permeable to K than to Na • b=Pna/Pk =0.02 • c=PCl/Pk • The membrane is so impermeable to Chloride that you drop it from the equation

37. Em= 61.54 mV log [K]o+b[Na]o [K]I+b[Na]I Should equal depending in initial given concentrations: -60 to -100 mV

39. Goldman Equation • Em= RT/F ln Pk[K]o+Pna[Na]o+PCl[Cl]i Pk[K]I+Pna[Na]I+PCl[Cl]o Also known as the constant field equation because it assumes that electrical field of the membrane potential is equal across the span of the membrane