Histology of the Nervous System

Question 1

Glial cells

Answer 1

• support cells:
  
  • astrocytes
  • oligodendrocytes
  • schwann cells
  • ependymal cells
  • satellite cells of ganglia

Question 2

choroid plexus

Answer 2

specialized epithelial cells on surface of ventricles that produce CSF

Question 3

ependymal cells

Answer 3

• low columnar or cuboidal cells that line the central canal of the SC and ventricle within the brain
• some have cilia on apical surface to aid CSF flow
• differ from epithelial cells - non-basal laminar due to projections down into the SC

Question 4

What are the components of the neuronal cytoskeleton?

Answer 4

• actin
  
  • dynamic assembly/dissasembly that allows shape changes and movement
• intermediate filaments
  
  • in all + other cells, permanent
• microtubules
  
  • dynamic, axon transport of proteins and signalling processes (i.e. NOT APs)

Question 5

Nissl bodies

Answer 5

• RER, ribosomes i.e. sites of protein synthesis stained in neurons

Question 6

Astrocytes

Answer 6

• glial cells
• passive support functions:
  
  • NT uptake and degradation, mainly GABA and glutamate
  • K+ homeostasis to allow repolarization between APs
  • energy supply to neurons via processes that wrap around blood vessels (e.g. for glucose metabolism)
  • BBB maintenance
  • formation of myelin sheath around axons
  • injury response and recovery
• active functions:
  
  • modulation of neural function (eg release NTs like glutamate and ATP)
  • modulation of blood flow (e.g. Ca2+ release)
    
    • in response to NTs, trauma, inflam mediators, or spontaneously

Question 7

Ca2+ excitation of glial cells causes what in neurons?

Answer 7

hyperpolarization and tf inhibition

Question 8

Oligodendrocytes

Answer 8

• predominant glial cell of white matter
• myelinate axons in CNS
  
  • Schwann cells posess this function in the PNS

Question 9

Microglia

Answer 9

• NOT glial cells
• main (innate) immune cells of the CNS
  
  • macrophage origin from bone marrow
• activated in injury and disease
  
  • release chemical mediators, cytokines, growth factors
    
    • can be damaging
• important in CNS development (size and shape of neurons, connections)
• survey normal synaptic functioning
  
  • contact synapses via mobile processes to ‘check’

Question 10

Perineurium

Answer 10

collagenous tissue that envelops individual fasicles/nerve fibres

Question 11

Epineurium

Answer 11

if there is more than one fasicle in a peripheral nerve; collagenous tissue that envelops the fasicles (enclosed in perineurium)

Question 12

Endoneurium

Answer 12

surrounds each Schwann cell and its associated axon (i.e. nerve fibres)

Question 13

Sensory ganglia

Answer 13

• i.e. dorsal root ganglia
• contain cell bodies of sensory nerves
  
  • afferent input into SC

Question 14

Autonomic ganglia

Answer 14

• cell bodies of post-ganglionic neurons
  
  • eg enteric NS of gut

Question 15

Ganglia contain

Answer 15

cell bodies, nerve fibres, and satellite cells (glial cells of ganglia)