Page 366 - Atlas of Histology with Functional Correlations

and myelinate numerous axons

GRAY AND WHITE MATTER

Gray matter contains neurons, dendrites, and neuroglia

Gray matter is the site of connections or synapses between neurons and
dendrites
Posterior horns of the spinal cord are associated with axons of posterior roots
Anterior horns of the spinal cord are associated with axons of anterior roots

White matter contains only myelinated axons, unmyelinated axons, and
neuroglia

SYNAPSES

Specialized sites for the transmission of chemical/electrical communication
Transmission is unidirectional from presynaptic to postsynaptic neurons

The three main synapses are axodendritic, axosomatic, and axoaxonic
Consist of presynaptic component, synaptic cleft, and postsynaptic
membrane
Transmit nerve impulses from presynaptic to postsynaptic cells

Convert impulses into signals to affect postsynaptic cell activities
Most synapses contain chemical neurotransmitters in presynaptic regions
Neurotransmitters cross synaptic cleft and bind with receptors on the
postsynaptic membrane

Neurotransmitters produce either excitatory or inhibitory responses
Summation of excitatory or inhibitory effects on the target regulates the
effects of stimulus
After release, the neurotransmitters are quickly removed from synaptic clefts

SPINAL CORD

Thoracic region of spinal cord contains anterior, posterior, and lateral gray

horns
Lateral horns contain motor neurons of sympathetic division of autonomic

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