Nervous Tissue

Question 1

Glial Cells of the CNS

Answer 1

• Oligodendrocytes (make myelin sheathe)
  
  • small dark staining nucleus in neuropil
• Astrocyte (provide support & help form BBB)
  
  • larger granular nucleus in neuropil
• Microglia (phagocytic cells; adapted macrophage)
• Ependymal cells (make CSF & cilia aid in CSF circulation)

Question 2

Glial cells of the PNS

Answer 2

• Schwann cells (make myelin sheathes)

- Satellite cells

Question 3

Embryologic Origin of the CNS & PNS

Answer 3

• CNS arises from the neural tube

- PNS arises from the neural crest

Question 4

Types of neurons

Answer 4

• unipolar/pseudounipolar
• bipolar
• multipolar
  
  • pyrimidal neurons (special in cerebral cortex)
  • purkinje neurons (special in cerebellum)

Question 5

What is the neuropil?

Answer 5

The “connective” tissue of the CNS

Question 6

Stains used in the nervous system

Answer 6

• Nissl stain
  
  • stains neuron RER (nissl substance) blue and granular
• Myelin stain
  
  • stains myelin lipids black

Question 7

Functions of the Axon

Answer 7

send information via synapse to another nerve cell or organ

Question 8

Features of an axon

Answer 8

• Single
  
  • CAN HAVE COLLATERAL BRANCHES
  • collateral branches arise from nodes of ranvier
• myelinate or un-myelinated
• great variability in length
• terminal branches form telodendria

Question 9

Three Classifications of Axons

Answer 9

A axons: largest in diameter & myelinated
B axons: medium diameter & myelinated
C axons: smallest diameter & unmyelinated

** signals travel speed decreases from A-C**

Question 10

Types of synapses (classified by what structures they are between)

Answer 10

1. Axo-dendritic
2. Axo-somatic
3. Axo-axonal
4. Serial (axo-axo-dendritic)
5. dendrodendritic

Question 11

Peptidergic neurons

Answer 11

The Golgi body of the neuron packs protein into the pre-synaptic vesicles

Question 12

Small-molecule secreting neurons

Answer 12

The golgi makes empty vesicles and the pre-synaptic cleft packages the neurotransmitter

Question 13

Axonal Transport

Answer 13

• Slow component
  
  • only in orthograde direction (body to synapse)
• Fast component
  
  • Orthograde (kinesin)
  • Retrograde (dynein) –> slower than orthograde

Question 14

Neuron Degeneration Types

Answer 14

• Wallerian (Orthograde) Degeneration

- Retrograde Degeneration

Question 15

Wallerian (Orthograde) Degeneration

Answer 15

• occurs peripherally
• schwann cell sheathe & connective tissue layers remai
• Regeneration can occur

Question 16

Retrograde Degeneration

Answer 16

• Degeneration of axon & myelin sheath in direction of cell body
• usually doesn’t degrade all the way to the cell body

Question 17

Nerve Regeneration

Answer 17

• only successful in the PNS
• can result in neuromas
  
  • axon grows out into a ball & causes pain