Histology of Nervous Tissue
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Transcript of Histology of Nervous Tissue
Histology of Nervous Tissue
PROF. DR. FAUZIAH OTHMANDEPT OF HUMAN ANATOMY
Feature of nerves tissue Type of cell: neuron & neuroglia General feature of neuron Type of neuroglia: astrocyte, oligodendrocyte,
ependymal cell, microglia Synapses Myelin – formation & function General structure of peripheral nerves Ganglia – dorsal root ganglia & autonomic ganglia
Nervous system divided into:
Central nervous system (CNS)Brain and spinal cord
Peripheral nervous system (PNS) Cranial and spinal nerves – locate outside the CNS.
Morphology of typical neuron Neuron functional cell of the nervous tissue.
Cell body or perikaryon - contains the nucleus – regulates the functioning of the neuron.
Numerous dendrites and a single axon. Contains Nissl bodies in the cytoplasm Axon hillock- no Nissl bodies
Axon – cellular process (extension) – carries impulses away from the cell body.
Dendrites – cellular process (extension) – carries impulses
toward the cell body
2 types of cell
i) Neurons (nerve cells)ii) Supporting cells
Functions of neurons
1) specialized to receive stimuli and to conduct electrical impulses to other parts of the system.
2) Arranged as an integrated communications network, with several neurons in a chain-like fashion involved in sending impulses from one part of the system to another.
Neuron Classification Structural:
Multipolar – most common type in CNS. Include all motor neurons and interneurons of brain
and spinal cord.
Bipolar- not as common purely sensory. Retina of eye, inner ear, olfactory epithelium in the
upper region of nose.
Unipolar (formerly known as pseudounipolar)
Sensory neurons found in numerous craniosacral ganglia of the spinal cord.
Comparison of Structural Classes of Neurons
Comparison of Structural Classes of Neurons
Comparison of Structural Classes of Neurons
Unipolar neuron
Nucleus & nucleolus
Cytoplasm
fibrocytes
Satellite cells
Cytoplasm of neuron
Myelinated axons
The supporting cells (neuroglia or glia):
Astrocytes Oligodendrocytes Microglial cells Ependymal cells Schwann cells Satellite cells PNS
CNS
Astrocytes
Largest, most numerous, versatile, and highly branched glial cells
They cling to neurons and cover capillaries Functionally, they:
Support and brace neurons Anchor neurons to their nutrient supplies Guide migration of young neurons Control the chemical environment
Astrocytes
Microglia Microglia – smallest, ovoid cells with spiny
processes- phagocytic cells that migrate through the CNS and remove foreign and degenerated material
Ependymal Cells Ependymal cells – squamous- to
columnar-shaped cells They line the central cavities of the brain and
spinal column
Oligodendrocytes
Oligodendrocytes – branched cells that wrap CNS nerve fibers
- Produce myelin in CNS
Schwann Cells and Satellite Cells Schwann cells (neurolemmocytes) – form myelin
sheaths around peripheral axons
Satellite cells surround neuron cell bodies with ganglia
Synapse The region where the terminals come close to
another cell and transmit the impulse
A junction that mediates information transfer from one neuron: To another neuron To an effector cell
Presynaptic neuron – conducts impulses toward the synapse
Postsynaptic neuron – transmits impulses away from the synapse
Myelin – formation & function Whitish, fatty (protein-lipid), segmented
sheath around most long axons Its function:1. Protection of the axon2. Electrically insulating fibers from one
another3. Increasing the speed of nerve impulse
transmission
2 types of neuroglia produce myelin CNS= Oligodendrocyte PNS= Schwann cells