Transcript What is the structure of the spinal cord?

Psychology 304:
Brain and Behaviour
Lecture 9
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The Structure and Cells of the Nervous System
1. What is the structure of the spinal cord?
2. What is the structure of the neuron?
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By the end of today’s class, you should be able to:
1. discuss the neurological correlates of Parkinson’s
disease and Huntington’s disease.
2. distinguish between grey and white matter in the
spinal cord.
3. distinguish between dorsal and ventral root nerves.
4. describe the external structural features of the neuron.
5. describe the internal structural features of the neuron.
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What is the structure of the spinal cord?
• A horizontal section of the spinal cord reveals an Hshape of gray matter surrounded by white matter.
Gray matter: bodies of nerve cells (i.e., cell bodies)
White matter: projections from cell bodies to other
neurons (i.e., axons).
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The Spinal Cord
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The Spinal Cord
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• All dorsal root nerves are afferent, carrying sensory
information about the external environment and
internal organs to the spinal cord.
• All ventral root nerves are efferent, carrying motor
signals from the spinal cord to the muscles and internal
organs.
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Dorsal and Ventral Root Nerves
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What is the structure of the neuron?
• The external structure of the neuron is characterized by
eight features:
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Cell body: The metabolic center of the neuron. Also
called the soma.
Cell membrane: A semipermeable membrane that encloses
the neuron.
Axon: A long, narrow extension that projects from the cell
body.
Axon hillock: The cone-shaped region at the junction
between the axon and cell body.
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Myelin sheath: Fatty insulation surrounding the axon.
Nodes of Ranvier: Gaps between sections of myelin.
Dendrite: A short extension emanating from the cell body
that receives contacts from other neurons.
Terminal buttons (axon terminals): Button-like endings
on axon branches that contain chemicals for
communication between cells (i.e., neurotransmitters).
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Dendrite
Terminal button
Cell body
Axon
Cell membrane
Nodes of
Ranvier
Myelin sheath
Axon hillock
External Features of a Typical Neuron
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Image of a Neuron Produced by
Light Microscopy
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• The internal structure of the neuron is characterized by
nine features:
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Nucleus: The spherical DNA-containing structure of the
cell body.
Cytoplasm: The clear internal fluid of a cell.
Mitochondria: Sites of energy production and release.
Endoplasmic reticulum: A system of folded membranes;
Rough portions are involved in protein synthesis. Smooth
portions are involved in fat synthesis.
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Ribosomes: Located on rough endoplasmic reticulum.
Cellular structures on which proteins are synthesized.
Golgi complex: A system of membranes that packages
molecules in vesicles.
Microtubules: Tubules that allow for the rapid transport
of material throughout neurons.
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Golgi complex
Endoplasmic
reticulum
Ribosomes
Internal Features of the Cell Body
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The Structure and Cells of the Nervous System
1. What is the structure of the spinal cord?
2. What is the structure of the neuron?
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