Lab Activity 12

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Lab Activity 12

• Histology of Nervous Tissue
• Martini Chapter 12

Portland Community College BI 231
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Neuron
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Myelin

• Multilayered lipid and protein covering formed by
  Schwann cells around axons
• Oligodendrocytes in the CNS
• The covering is the plasma membrane of the
  Schwann Cell
• The Schwann Cell can cover more than one axon
• Insulates axon

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Nodes of Ranvier

• Areas between Schwann Cells that do not contain
  Myelin
• Involved in saltatory conduction

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Dendrite
Neuron Cell Body
Nucleus
Axon Hillock
Axon
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Schwann Cell
Axon
Node of Ranvier
Myelin Sheath
Telodendria
Axon Terminal (Synaptic end bulbs)
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Unipolar Neuron
Dendrite (trigger zone)
Axon
Cell Body

• All are sensory afferent
• Cell bodies are located in the dorsal root ganglia

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Bipolar Neuron
Axon
Dendrite (trigger zone)
Cell Body

• Location special senses (smell, vision, hearing)

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Multipolar Neuron
Cell Body
Axon
Dendrites (trigger zone)

• Most common type of neuron
• Interneurons and motor neurons

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Motor (Efferent) NeuronsEfferent Away from CNS

• These are neurons that carry information from CNS
  to the body
• Groups of axons running together are the Nerves
  when they are outside the CNS and Tracts inside
  the brain and spinal cord
• The cell bodies are clustered in groups in the
  CNS and are called nuclei
• Brain gray matter is made up of millions of
  nuclei.
• It is gray because there is no myelin around the
  cell bodies
• These axons exit the spinal cord on the ventral
  side

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Sensory (Afferent) NeuronsAfferent Toward the
CNS

• These carry sensory information from the body to
  the CNS (brain and spinal cord)
• Their axons run in the same group as the motor
  neurons (nervesgroups of axons)
• Their cell bodies are clustered outside of the
  spinal cord and are called ganglia
• These axons enter the spinal cord on the dorsal
  side

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Association or Interneurons

• Neurons between the afferent and efferent
  neurons.
• Are only in the CNS

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Axon
Myelin Sheath
Neuron
Node of Ranvier
Perineurium
Fascicle
Epineurium
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Glial Cells

• Associated with neurons
• Provide Supportive scaffolding
• Segregate and insulate neurons
• Outnumber neurons by 10 to 1

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Supporting Cells in the CNS Astrocytes

• Star Shaped
• Many functions
• Control the chemical environment around neurons
  by buffering K and NT
• Exchanges between capillaries and neurons
  (blood-brain barrier)
• Nutrient transfer

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Supporting Cells in the CNS Oligodendrocytes

• Oligodendrocytes produce the myelin sheath which
  provides the electrical insulation for some
  neurons in the CNS

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Supporting Cells in the CNSMicroglia

• Small oval cells with long thorny processes
• Monitor the health of neurons
• Specialized immune cells that phagocytize
  microorganisms and debris
• Immune system cells do not have access to CNS

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Supporting Cells in the PNS Schwann Cells

• Form the myelin sheath around axons in the PNS

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Schwann Cell
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The End
The End