Page 367 - Atlas of Histology with Functional Correlations

nervous system

Anterior horns of gray matter contain motor neurons
Axons from anterior horns form anterior roots of spinal nerves
White matter contains closely packed ascending and descending axons
Posterior columns of white matter contain fasciculus gracilis and fasciculus
cuneatus

Gray matter inside the spinal cord is H-shaped and contains neurons and
interneurons
Gray commissure connects two sides of the gray matter and contains the

central canal

NEURONS, AXONS, AND DENDRITES

Classified as afferent (sensory), efferent (motor), or interneurons
Somatic afferent fibers conduct impulses from body surface and body organs
to the CNS
Visceral afferent fibers conduct impulses from internal organs, glands, and

blood vessels to the CNS
Efferent fibers conduct from the CNS to the effector organs in the peripheries
Interneurons act as intermediaries between different neuron types
Neuron cell body and dendrites contain Nissl substance (granular

endoplasmic reticulum)
Neurofibrils in the neuron cell body extend into dendrites and axons
Axons arise from a funnel-shaped region called an axon hillock
Axons and axon hillocks are devoid of Nissl substance

Neurons show irritability and conductivity and synthesize various products
Neurons synthesize neurotransmitters and neurohormones in the cell body
Axons transport neurotransmitters in microtubules to synapses
Stimuli cause conduction of nerve impulse (action potential) along the axons

Initial segment of an axon is the site where stimuli are summated and nerve
impulse is generated
Rate of impulse conduction dependent on axon size and myelination
Dendrites are covered with dendritic spines for connections (synapses) with

other neurons
Dendrites receive and integrate information from dendrites, neurons, or
axons
Axons also exhibit bidirectional transport of chemicals, organelles, and

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