Found around the segments of myelin sheath.

They form the myelin sheath by rotating several times around the axon.

Thus forming a series of rings of phospholipid which will be the myelin sheath.

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Act as insulator for nerve impulse. Regeneration of neurones after injury. Formation of myelin sheath in peripheral

nerves .

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The point of contact between the processes of the neurons.

The synapse is composed of three parts: 1. Presynaptic terminal: (End bulb) The terminal part of axon delivers the

impulse to the synaps. It contain many mitochondria and

neurovisicles or neurotransmitter rich in Acetylcholine .

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Synaptic cleft : The distance between 2 synaptic

membrane . Filled with chemical transmitter. It contain enzymes that destroy the

molecules of transmitter. Postsynaptic membrane: The membrane of other dendrite. Type of synapse: Axo-dendritic synapse. Axo-somatic sypase. Axo-axonic synapse.

The nerve trunk is formed of collections of axons arranged in bundle bound together by C.T.

Epineurium: surround the whole N.T. Perineurium: surround the nerve bundle. Endoneurium: surround the nerve fiber.

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Composed of nerve cells and nerve fiber surrounded by C.T. called capsule

There are 2 types : Spinal ganglia . Autonomic ganglia . Sympathatic ganglia . Parasympathatic ganglia

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Spinal ganglia are exist beside the spinal cord at its both side.

Formed of pseudounipolar nervw cell. Each cell is surrounded by small satellite

cell, which are supportive and nutritive in functions to nerve cell .

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Sympathatic ganglia : Exist in several region of the body, formed

of multipolar stellate-shaped nerve cells, surrounded by few satellite cells

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Represent the supporting tissue, instead of C.T. between the neurons of C.N.S.

Neuroglia may be classified into: Neuroglia proper. Macroglia or Astrocyte . Microglia or Mesoglia . Oligodendroglia

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Other types of Neuroglia Ependymal cell Satellite cells Neurolemmal or Schwann cell . Spongioblast cell

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