Nervous tissue 神经组织

1. Nervous tissue神经组织 Jun Zhou(周俊) School of Medicine, Zhejiang University 20140325

2. Overview ---Components: • nerve cell: neuron • Glial cell: neuroglia ---Function: • Neurons : receive the stimulation, conduct the nerve impulse • Glial cell: support, protect and insulate, nourish neurons

3. Synapse neuron • neuron Nerve fiber neuroglial ending

4. Neuron The structural and functional cellular unit

5. LM: ---cell body: spherical, pyramidal fusiform or stellate in shape, 5um-150um ---dendrite （树突） ---axon （轴突）

6. structure of neuron ①cell body: ---cell membrane: • unit membrane-irritability, receive stimuli, initiate and conduct nerve impulse • membrane proteins - ions channel and receptor

7. cell nucleus: • large and round • centrally- located • less heterochromatin • pale stained, with a clear nucleolus

8. ---cytoplasm: perikaryon a.Nissl body (尼氏体): LM: basophilic granule-liked structure EM: parallelly-arranged RER and free ribosome Function: synthesis proteins • structural protein • enzymes of neurotransmitters

9. b.Neurofibril(神经原纤维): • silver impregnation methods (silver preparation) • thread-liked dark brown color structure to form a network.

10. EM: • neurofilament: 10 nm in diameter • microtubule: 25 nm in diameter Function: • supporting • involving in intracellular transportation

11. c.other organelle • Golgi apparatus • mitochondria • pigment

12. ②     dendrite(树突): • many, short and more branches • structure similar to cell body • dendritic spine (synapse) and spine apparatus (structure formed by 2-3 layers SER) • Function: receive the information

13. ③    axon(轴突): • thin, less branch • axon hillock(轴丘): the beginning without Nissl body • axolemma • axoplasm ---Function: initiate an impulse and conduct the impulse

14. * axonal transports • slow anterograde cytoskeletal protein: microtubule, microfilament and neurofilament (0.1-0.4 mm/d) • fast anterograde synaptic vesicles, enzymes and proteins( 100-400 mm/d) • fast retrograde products of metabolism, intaking materials including protein or neurotropic factors (100-300 mm/d)

15. 3) classification: ---According to the number of processes • multipolar neuron • bipolar neuron • pseudounipolar neuron

16. ---According to length of axon • Golgi type I neuron long axon and large • Golgi type II neuron short axon

17. ---According to function • sensory neuron • motor neuron • interneuron

18. ---According to the neurotransmitter or neuromodulator • cholinergic neuron • aminergic neuron • peptidergic neuron • aminoacidergic neuron

19. Synapse (突触)

20. ---definition: the junctions between neurons or neuron and non-nerve cells ---classification: • chemical synapse: taking neurotransmitter as communicating medium • electrical synapse: gap junction

21. ---structure of chemical synapse: LM • in silver preparation • on the surface of dendrites and cell body • button-liked structures (synaptic button)

22. EM 1)presynaptic element: axonal terminal • presynaptic membrane • synapse vesicle: -round or flattened, 40-60nm -clear or with electron dense core 2)synaptic space:15-30nm 3)postsynaptic element: • postsynaptic membrane • receptors

23. Glial cell (neuroglia)神经胶质细胞

25. Glial cell in CNS • Astrocyte (星形胶质细胞) • fibrous astrocyte • protoplasmic astrocyte • Oligodendrocyte (少突胶质细胞) • Microglia (小胶质细胞) • Ependymal cell (室管膜细胞)

26. fibrous astrocytes -white matter, have long, thin and smooth processes -more glial filament- glial fibrillary acidic protein, GFAP • protoplasmic astrocytes -gray matter, short, thick processes with more branch -less glial filament

27. Oligodendrocyte(少突胶质细胞): • smaller, fewer process • form myelin-sheath of NF in CNS

28. Microglia(小胶质细胞): • smallest, elongate shape or ovoid, with a small dark irregular N • phagocytosis- mononuclear phagocyte system？

29. Ependymal cell (室管膜细胞): • simple cuboidal or columnar epi • apical: microvilli and cilia • basal: long processes ---Distribution: ventricle of brain and central canal of spinal cord

30. Glial cell in PNS a. Schwann cell: form myelin-sheath in PNS b. Satellite cell (capsular cell): surrounding the Neuron in ganglion

31. Nerve fiber and Nerve • formed by axon and glial cell • classification • myelinated nerve fiber (有髓神经纤维) • unmyelinated nerve fiber (无髓神经纤维)

32. Myelinated nerve fiber LM: • Axon • myelin-sheath: • net-liked • OsO4(osmium tetroxide) fixation and stain • Schmidt-Lantermann incisure • neurilemma: cell membrane +basement membrane • Schwann cells (PNS) • Oligodendrocyte (CNS)

33. Ranvier node (郎飞结): narrow part, no myelin-sheath- saltatory conduction • Internode segment (结间体): the segment of NF between two Ranvier nodes

36. MNF in CNS • similar to that of PNS • oligodendrocyte • one oligodendrocyte can envelop many axons • no incisure and basement membrane

37. Unmyelinated nerve fiber • thin axon and Schwann cell connect end to end • no myelin-sheath and Ranvier node • one Schwann cell envelops more axons • naked axon (CNS)

38. Nerve ---Nerve fiber gets together • Epineurium • perineurium • endoneurium

39. Blood brain barrier (血脑屏障) • Endothelial cell of continuous Cap. • basement membrane • Foot processes of astrocytes

40. Nerve Ending

41. Sensory nerve ending 1.Free nerve ending ---function: feel cold, hot, pain and slight touch 2.Encapsulated N ending ---have CT capsule • Meissner’s corpuscle (tactile)触觉小体: touch receptor • Pacinian corpuscle(lamellar)环层小体: pressure receptor • Muscle spindle(肌梭): tension receptor

42. Muscular spindles tactile corpuscle lamellar corpuscle

43. Motor nerve ending • Somatic MNE: motor end plate ( neuromuscular junction) • Visceral MNE

44. THE END