Page 368 - Atlas of Histology with Functional Correlations

neurotransmitters

Anterograde transport is via microtubules in axons to axon terminals or
synapses
Retrograde transport is via microtubules from axon terminals and dendrites to
neurons
Axonal transport requires microtubule-associated motor proteins kinesin and

dynein

SUPPORTIVE CELLS IN CNS:

NEUROGLIA

Supportive, nonneural cells that surround neurons, axons, and dendrites
Small cells that do not conduct impulses
Ten times more numerous than neurons
Four types: astrocytes, oligodendrocytes, microglia, and ependymal cells

Astrocytes

Are the largest and most numerous in gray matter
Consist of two types: fibrous astrocytes and protoplasmic astrocytes

Both types abut on capillaries and form tight junctions and blood–brain
barrier
Form glial limiting membrane that surrounds the brain and the spinal cord
Support metabolic exchange and contribute to the energy metabolism of the

CNS
Control the chemical environment around neurons by clearing increased
potassium ions and neurotransmitters such as glutamate
Gap junctions form structural syncytia in the CNS and the communication

network in the brain
In response to injury, cells divide and form scar tissue

Oligodendrocytes

Surround and myelinate numerous axons at one time, in contrast to Schwann
cells
Do not surround multiple and unmyelinated axons

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