1. Nervous Tissue

2. Nervous System • CNS (brain and spinal cord) • PNS (peripheral nervous system)

3. Types of Cells • Neurons – structural units • Supporting cells – protect and myelinate neurons

4. Structure of Neurons • Cell body – contains nucleus and cytoplasm

6. Structure of Neuron • Dendrites – receptive regions

8. Structure of Neuron • Axons – nerve impulse generators

10. Structure of Neuron • Axoplasm – cytoplasm of neuron

12. Structure of Neuron • Axolema – plasma membrane

14. Structure of Neuron • Collaterals – axon branches

16. Structure of Neuron • Axon hillock – an enlarged cell body structure, which is the beginning of the axon

18. Structure of Neuron • Axon terminals – The axon and its collaterals end divide into fine processes

20. Structure of Neuron • Synaptic end bulbs – tips of axon terminals that contain the synaptic vessicles

22. Structure of Neuron • Synaptic cleft – gap between two neurons

23. Structure of Neuron • Supporting cells wrap themselves around the axons of some neurons like a jelly role

24. Structure of Neuron • Myelin sheath – A tight core of plasma membrane material around the axon

27. Structure of Neuron • Neurilemma – The peripheral part of the schwann cell and the exposed plasma membrane

29. Structure of Neuron • Nodes of Ranvier – Since the myelin sheath is composed of several schwann cells there are gaps or indentations called nodes of ranier

31. Classification by Structure • Unipolar • Bipolar • Multipolar

32. Unipolar • Have only one process that extends from the cell body

34. Unipolar • Conduct impulses toward the CNS

35. Bipolar • Have two processes that extend from the cell body (one axon and one dendrite)

37. Bipolar • Found in the eye, ear, and olfactory mucosa

38. Multipolar • Have several processes that extend from the cell body (several dendrites and one axon)

40. Multipolar • Most neurons in CNS and neurons that carry impulses away from the CNS

41. Classification by Function • Sensory • Motor

42. Sensory or Afferent Neurons • Carry impulses away from sensory receptors in the skin, skeletal muscle, and internal organs.

43. Sensory or Afferent Neurons • Most are unipolar

44. Sensory or Afferent Neurons • Cell bodies lie outside the CNS

46. Motor or Efferent Neurons • Carry impulses away from the CNS

47. Motor or Efferent Neurons • Most are multipolar

48. Motor or Efferent Neurons • Cell bodies lie within the CNS

50. Neuroglia • Supporting cells