Histology of Nervous Tissue - PowerPoint

Document Sample
Histology of Nervous Tissue - PowerPoint Powered By Docstoc
					Histology of Nervous
              Tissue




       PROF. DR. FAUZIAH OTHMAN
        DEPT 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
                         CNS
 

    Ependymal cells
    Schwann cells
    Satellite cells    PNS
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 axon
2.   Electrically insulating fibers from one
     another
3.   Increasing the speed of nerve impulse
     transmission
2 types of neuroglia produce
myelin
   CNS= Oligodendrocyte
   PNS= Schwann cells

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:325
posted:9/1/2012
language:Unknown
pages:39