Nerves I and II

Question 1

describe the neural cell body

Answer 1

• called soma
  
  • euchromatic nucleus
  • Nissl bodies
    
    • stacks of rER
  • numerous mitochondria
  • large perinuclear Golgi

Question 2

Answer 2

Question 3

describe dendrites

Answer 3

• carry information towards the cell body
• greater diameter than axons
• unmyelinated

Question 4

describe axons

Answer 4

• carry information away from cell body
• 1 axon for each neron
• axon hillock
  
  • conical projection of cell body
  • devoid of Nissl bodies
  • lacks large organelles
• plasma membrane = axolemma
• contents = axoplasm

Question 5

describe Golgi Type I and II neurons

Answer 5

• Golgi Type I neurons
  
  • motor nuclei of CNS
  • axons more than 1 meter long
    
    • skeletal muscle
• Golgi Type II neurons
  
  • short axons
  • Golgi cells in cerebellum
  • interneurons

Question 6

describe the axon transport systems

Answer 6

• Anterograde transport:
  
  • cell body to periphery
  • kinesin
• retrograde transport:
  
  • axon terminal and dendrites to cell body
  • Dynein

Question 7

name the peripheral vs central nueroglial cells

Answer 7

• peripheral neuroglial:
  
  • Schwann cells
  • satellite cells
• central neuroglial:
  
  • microglia
  • ependymal cells
  • astrocytes
  • oligodendrocytes

Question 8

describe Schawnn cells

Answer 8

• originate from neural crest cells
• responsible for myelination in PNS
• only axon hillock and terminal arborizations are free of myelin
• multiple layers of Schwann cell membrane wrapped concentrically around an axon

Question 9

Answer 9

myelinated nerve fiber

Question 10

describe demyelinating diseases

Answer 10

• Guillan-Barre Syndrome
  
  • disease of PNS
  • nerve fibers accumulate lymphoctes, macrophages and plasma cells and leads to loss of muscle coordination and cutaneous sensation
• MS
  
  • preferential damage to myelin – detach from axon and destroyed
  • damage to oligodendrocytes
  • 3 histological stages in the demyelinating process:
    
    • myelin breakdown associated with lymphocyte and macrophage infiltration of affected area - plaque
    • proliferation of astrocytes - gradual infiltration of astrocytes into demyelinating area
    • reduced cellularity, astrocyte reduce in size

Question 11

Answer 11

pathology of MS

• W = white matter
• D = demyelinating region
• L = lymphocytes

Question 12

describe satellite cells

Answer 12

• surround ganglionic neuronal cell bodies
• cuboidal
  
  • form complete layer around cell body
    
    • only nuclei are visible
• originate from neural crest cells
• analogous to Schwann cells
  
  • insulation
  • nutrition

Question 13

Answer 13

• satellite cells

Question 14

describe oligodendrocytes

Answer 14

• derived from the neural tube
• CNS myelin formed by:
  
  • concentric layers of oligodendrocyte plasma membrane

Question 15

Answer 15

myelin sheath of the CNS made by oligodendrocytes

Question 16

describe astrocytes

Answer 16

• largest of glial cells
• derived from the neural tube
• 2 kinds are seen:
  
  • protoplasmic
    
    • prevalent in gray matter
  • fibrous
    
    • prevalent in white matter
• have elaborate processes extending b/t vessels and neurons
• may have a role in regulating tight junctions of BBB

Question 17

Answer 17

astrocytes

Question 18

describe microglia

Answer 18

• part of mononuclear phagocytic system
• derived from monocyte precursor
• present in small numbers
  
  • proliferate during injury/disease
  • actively phagocytic
• secrete immunoregulatory cytokines that dispose of unwanted cellular debris

Question 19

Answer 19

microglia

Question 20

describe ependymal cells

Answer 20

• produce and secrete CSF

Question 21

Answer 21

ependymal cells