Chapter 2

1. Chapter 2 Nerve Cells and Nerve Impulses

2. Chapter Overview • Cells of the nervous system • Structure of neurons • Blood brain barrier • Nerve impulse • Resting potential • Action potential • Graded potentials

3. An electron micrograph of parts of a neuron from the cerebellum of a mouse

4. Neuron Membrane

5. The components of a vertebrate motor neuron

6. Stop And Check • Know the parts of a neuron and what they do: • Dendrites • Dendritic spines • Cell body (soma) • Axon • Myelin sheath • Presynaptic terminal

7. Neuron Quiz

8. A vertebrate sensory neuron

9. Haines, 1997 Purkinje Cell Of Cerebellum

10. Allyn & Bacon, 1992 Interneuron

12. Stop And Check • What distinguishes each of the following types of neurons? • Motor • Sensory • Intrinsic • Afferent • Efferent

13. Please select a Team. • Cubs • White Sox • Cardinals • Other

14. The Function of a Neuron is Closely related to its shape • True • False

15. Chemicals than cannot flow freely across a cell membrane enter a neuron through: • gaps in the myelin sheath. • specialized protein channels. • the endoplasmic reticulum. • a Golgi complex.

16. Which of the following is the correct order of transmission of information within a neuron? • cell body, dendrite, axon • dendrite, cell body, axon • axon, cell body, dendrite • dendrite, axon, cell body

17. Which of the following glial cell is important for myelination in the central nervous system? • Radial glia • Microglia • Schwann cell • Oligodendrocyte

18. Team Scores

19. The Blood-Brain Barrier (BBB) • Why a BBB? • How it works

20. O O Blood Brain Bacteria

21. If you were a molecule trying to enter the brain, which of the following would most likely prevent you from getting in? • Being small and positively charged • Being small and fat soluble • Being large and negatively charged • Being large and fat soluble

22. The major disadvantage of the BBB is • It allows alcohol to easily pass • It requires energy to transport nutrients • Bacteria can easily enter the brain • I don’t know

23. The Nerve Impulse • Why a resting potential? (-70 mv)

25. Na+ Na+ Na+ K+ K+ Forces Behind The Resting Potential • Sodium-potassium pump

26. Forces Behind The Resting Potential • Selective permeability* • Large negatively-charged molecules inside axon

27. Forces Behind The Resting Potential • Concentration gradient • Electrical gradient • Voltage-activated channels

29. What is one major cause for the resting potential of a neuron's membrane? • Selective permeability of the membrane • The refractory period of the membrane. • A difference in size between axons and dendrites. • A high permeability of the membrane to water molecules.

30. The resting potential would _____ if the membrane was more permeable to sodium. • Become more positive • Become more negative • Remain the same • I don’t know

31. Resting Potential Depolarization Repolarization Na+ in K+ out Threshold of excitation Hyperpolarized

32. Conductance during action potential

33. I’m A Little Neuron • I’m a little neuron, short and stout. • Here is my dendrite, here is my spout. • When I reach my threshold, hear me shout, • “Let the sodium in, potassium out.”

34. All-or-None Law

35. Stop And Check • What factors contribute to the resting potential? • Know the molecular basis for the action potential including: • Relative concentrations of ions • Opening and closing of their channels • Role of electrical and concentration gradients • Threshold of excitation

36. Please select a Team. • Dendrites • Axons • Somas

37. Making the interior of the cell more negative will tend to keep potassium ions inside the neuron. • True for sure • Maybe true • Maybe false • False for sure

38. The sodium-potassium pump is what normally brings the membrane back to its original state of polarization immediately after the peak of the action potential. • True for sure • Maybe true • Maybe false • False for sure

39. Additional stimulation above the threshold of excitation will result in a greater depolarization of the membrane during an action potential. • True for sure • Maybe true • Maybe false • False for sure

40. If depolarization is less than the cell's threshold: • potassium is prevented from crossing the membrane. • sodium crosses the membrane only slightly more than usual. • sodium is prevented from crossing the membrane. • the cell will still produce an action potential.

41. The presence of an all-or-none law suggests that neurons can only convey different messages by changing their: • sodium-potassium pump activity. • speed of action potentials. • size of action potentials. • rate or pattern of action potentials.

42. Team Scores

43. Participant Scores

44. Resting Potential AbsoluteRefractoryPeriod Depolarization Repolarization Na+ in K+ out Threshold of excitation Hyperpolarized

45. Myelin & Saltatory Conduction Node of Ranvier

46. Signaling Without Action Potentials • Graded potentials • Depolarizations and hyperpolarizations of dendrites and cell bodies

47. Chapter Summary • Cells of the nervous system • Structure of neurons • Blood brain barrier • Nerve impulse • Resting potential • Action potential • Graded potentials