Transcript Nervous Tissue rawan turky

‫بسم هللا الرحمن الرحيم‬
NERVOUS TISSUE
RAWAN TURKY
 The neuron (nerve cell) is the structural and
functional unit of the nervous system.
 Nerve cell size range: 4µ up to 100µ.
 Cell membrane very thin
 Nucleus vesicular, spherical and central.
 No centrioles.
 Neurofibril of cytoplasm are parallel
 Nissl granules are characteristic to nerve cell
 Golgi complex surround nucleus and well
developed
 Nerve cell inclusion include glycogen, fat
droplets, Melanin pigments in addition to
lipofuscin granules (yellowish lipochrome
granules).
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Rawan turky
Types of Nerve cells
Unipolar nerve cell :
Pseudo-unipolar nerve:
Bipolar nerve cell
Multipolar nerve cell
Pyramidal cell
Types of Nerves Fibers or Axons
The axons may be naked or may be covered
with:
Myelin sheath
Neurolemma
Both
1. Naked nerve fiber:
No myelin sheath and no Neurolemma as
fiber in gray matter
2. Myelinated nerve fiber:
No Neurolemma as fibers in white matter.
3. Myelinated nerve fiber with Neurolemma
as the peripheral somatic nerves outside
the spinal cord.
4. Nerve fiber which are covered with
Neurolemma but no with myelin sheath as
the post ganglionic fibers.
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Rawan turky
Myelin sheath
 Cover the axon and formed by neurolemmal cells
which surround the peripheral nervs.
 In brain is formed by neuroglia or neuroglial
cells.
 Composed of choesterol, fatty acids and
phospholipid
 It is interrupted by:
 1. Non-myelinated Nodes of Ranvir.
 2. Lanterman’s clefts:
 Facilitated the passage of molecules from
Schwann’s cell to myelin.
 To maintain the myelin sheath in a good
condition.
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