Nervous Tissue

 

Nervous tissue contains little extracellular material.

Derivation

Neurons

Neuraglia

Synapses

• Specialized junctions for communication

• Components:

  • Presynaptic terminal with synaptic vesicles

  • Synaptic cleft

  • Postsynaptic membrane with receptors

• Types: axodendritic, axosomatic, axoaxonic

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4. Neuroglia (Supporting Cells)

CNS Glial Cells:

• Astrocytes: Structural support, blood-brain barrier, ion regulation

• Oligodendrocytes: Myelin formation in CNS

• Microglia: Phagocytic, immune defense

• Ependymal cells: Line ventricles and central canal, produce and circulate CSF

PNS Glial Cells:

• Schwann cells: Myelin formation in PNS; support unmyelinated axons

• Satellite cells: Surround neuronal cell bodies in ganglia, provide metabolic and structural support

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5. Myelin

• Concentric layers of lipid-rich membrane around axons

• Increases conduction velocity (saltatory conduction at nodes of Ranvier)

• Produced by:

  • Oligodendrocytes in CNS

  • Schwann cells in PNS

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6. Gray vs. White Matter

• Gray Matter: Contains neuronal cell bodies, dendrites, unmyelinated axons, glia, synapses

• White Matter: Contains myelinated axons and glia (no neuronal cell bodies)

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7. Ganglia

• Sensory Ganglia (dorsal root, cranial): Pseudounipolar neurons, surrounded by satellite cells

• Autonomic Ganglia: Multipolar neurons, less organized, surrounded by satellite cells

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Study Questions