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Psychology 304: Brain and Behaviour

Lecture 9

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The Structure and Cells of the Nervous System

2. What is the structure of the neuron?

1. What is the structure of the spinal cord?

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5. describe the internal structural features of the neuron.

4. describe the external structural features of the neuron.

3. distinguish between dorsal and ventral root nerves.

2. distinguish between grey and white matter in the spinal cord.

1. discuss the neurological correlates of Parkinson’s disease and Huntington’s disease.

By the end of today’s class, you should be able to:

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What is the structure of the spinal cord?

• A horizontal section of the spinal cord reveals an H-shape 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).

5The Spinal Cord

6The 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.

8Dorsal and Ventral Root Nerves

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• The external structure of the neuron is characterized by eight features:

What is the structure of the neuron?

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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

Myelin sheath

Axon

Terminal button

Cell body

Nodes of Ranvier

Cell membraneAxon hillock

External Features of a Typical Neuron

13Image 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.

Mitochondria: Sites of energy production and release.

Cytoplasm: The clear internal fluid of a cell.

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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Golgi complex: A system of membranes that packages molecules in vesicles.

Ribosomes: Located on rough endoplasmic reticulum. Cellular structures on which proteins are synthesized.

Microtubules: Tubules that allow for the rapid transport of material throughout neurons.

17Internal Features of the Cell Body

Endoplasmic reticulum

Ribosomes

Golgi complex

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The Structure and Cells of the Nervous System

2. What is the structure of the neuron?

1. What is the structure of the spinal cord?