Neurons and Glia

Question 1

describe the cytoskeleton and active transport in neurons

Answer 1

• microtubules
  
  • cross-linked by Tau protein
  • coupled with kinesin
    
    • fast anterograde transport
  • coupled with dynein
    
    • fast retrograde transport

Question 2

describe microfilaments and neurofilaments of neurons

Answer 2

• microfilaments
  
  • form network near membrane
    
    • movement of growth cone (development and repair)
    • endocytosis of vesicles
• neurofilaments
  
  • structural

Question 3

describe pseudounipolar neurons

Answer 3

• primary sensory afferents
  
  • cell bodies commonly form peripheral ganglia
    
    • spinal dorsal root ganglia
    • cranial nerve ganglia

Question 4

describe bipolar neurons

Answer 4

central or peripheral special sensory function

Question 5

describe multipolar neurons

Answer 5

• long axons (Golgi type I)
  
  • motor neurons
• short axons (Golgi type II)
  
  • local interneurons

Question 6

describe radial glia

Answer 6

• neuronal astrocytic and oligodendrocytic progenitors
• scaffold for neuronal migration
• become Bergman glia in cerebellum
• become Muller cells of the retina

Question 7

describe astrocytes

Answer 7

form gliotic scars

• regulation:
  
  • ions
  • synaptic transmitters
  • regional cerebral blood flow
• neuroprotection
  
  • BBB
  • limit oxidative damage
  • supply lactate
    
    • additional energy during deficit (injury)

Question 8

describe the role of astrocytes and ions

Answer 8

• calcium currents
  
  • influx and intercellular passage of Ca
    
    • linked to neuronal/vascular dynamics
• potassium buffering
  
  • pumps and transporters

Question 9

describe the role of microglia

Answer 9

• immunocompetent and phagocytic
  
  • protect neurons from micro-organisms and toxic effects of cellular debris
• secrete neurotrophic or neuron survival factors upon activation
• release cytotoxic molecules
  
  • pro-inflammatory cytokines
  • reactive O2 intermediates
  • proteases
• contribute to initiation of pathological neuronal degeneration

Question 10

describe oligodendrocytes

Answer 10

• central myelinating cells
  
  • spped propagation of electrical impulses along axons

Question 11

describe ependymal cells

Answer 11

• line ventricles
• secrete CSF
• scar-forming
• along with astrocytes and tight junctions, form CSF-brain barrier

Question 12

describe Schwann cells

Answer 12

• neural crest-derived
• some myelinate and others support
• guide axonal growth

Question 13

describe the process of regeneration of axons in the PNS

Answer 13

• following axonal transection:
  
  • distal axonal segment degenerates (Wallerian degeneration)
  • prox. axonal segment may form sprouts
  • Schwann cells:
    
    • proliferate, forming a guide tube
    • release nerve growth factors, encouraging axonal regeneration