Histology of the
Nervous Tissue
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nervous system overview
 Nervous system
Monitors and processes sensory information
from the environment and from within the
body
 Principal cell populations
Neuron - transmits impulses
Neuroglia - Support, protects and insulates the
nervous tissue
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Neural tissue location
Central Nervous Tissue
Brain
Spinal cord
Peripheral Nervous Tissue
Nerves
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The Anatomy of a Neuron
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Neuron structure
 Nissl bodies – clusters of RER and ribosomes
 Dendrites
Receptive region
 Axon or nerve fiber
Nerve impulse generator and transmitter
Axon hillock
Axon terminal or synaptic knobs
Collaterals with telodendria
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Neuron structure
 Synaptic terminals
Presynaptic membrane
Synaptic vesicles
neurotransmitter
Synaptic cleft
Postsynaptic membrane
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Neurons
 They make up the gray matter of the nervous
system
 Clusters of cell bodies, dendrites, unmyelinated
axons and neuroglias are called:
Nuclei if they are located in the CNS
Ganglia if they are located in the PNS
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Axons or nerve fibers
 Covered by myelin
Fatty material secreted by Schwann cells in
the PNS
Fatty material secreted by oligodendrocytes
in the CNS
Myelin insulates the axons
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Axons or nerve fibers
In the PNS
The wrapping of the Schwann cell around the
axon is called myelin sheath
Neurilemma
It is the peripheral layer of the Schwann
cell
It contains the nucleus and most of the
organelles
Nodes of Ranvier
Gaps between Schwann cells
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Neuron classification
 Anatomical or structural
Unipolar
Bipolar
Multipolar
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A Structural Classification of Neurons
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Neuron classification
Functional
Sensory neurons or afferent neurons
• deliver information from the body to the
CNS
• Typically unipolar or bipolar
• Body found in a ganglia (PNS)
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Neuron classification
Motor neurons or efferent neurons
• Carry impulse from the CNS to the
body
• Typically multipolar
• Body found in the CNS
Association (interneuron) neuron
• Found between and sensory and a
motor neuron
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Structure of a nerve
 Definition
Bundle of fibers wrapped in myelin and
connective tissue
Located in the PNS
 Classification
Sensory or afferent – going to the CNS
Motor or efferent- going to the body
Mixed – carry sensory and motor fibers
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Structure of a nerve
 The connective tissue that surrounds the fiber is
called
Endoneurium-covers each nerve fiber
Perineurium – covers a bundle of nerve fibers
The whole bundle is called fascicle
Epineurium – covers the whole nerve
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Electroencephalography
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Electroencephalography - EEG
 Measures brain activity
Alpha waves = awake with eyes closed.
Resting.
Alpha block
Beta waves = awake with eyes opened.
Alert.
Delta waves = normal during sleep
Theta waves = normal children, abnormal in
adults
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