PRESENTED BY:ORJI JONATHAN ORJI ( DE GENIUS)

GUIDED BY:PhD. TAMRIKO VALISHVILIDOCTOR OF MEDICINELECTURER ATSU.

Nervous system:Central nervous system (CNS): brain and spinal cord

Peripheral nervous system (PNS): cranialnerves and spinal nerves

Two types of cells: neurons( cells of the nervous system that can receive and sends signals)

and supporting (glial) cells

Parts of a neuronCell body- contains the nucleus and other

organelles

Dendrites- transmit electrical impulses TO thecell body

Axon- transmits impulse AWAY from the cell body

axons can be several feet long

“Axon hillock” is located near the cell bodynerve impulses originate there

Myelin is wrapped around the axon of many neurons

In periphery, myelin is produced by Schwann

cells

In CNS, it is produced by oligodendrocytes

SUPPORTING CELLS

Schwann cells, oligodendrocytes- producemyelin

Satellite cells- support neurons in PNSMicroglia-phagocytes in CNSAstrocytes- induces blood-brain barrier.Ependymal cells- special epithelium that linebrain ventricles and central canal of spinal cord

also part of structure that makes CSF

CLASSIFICATION OFNEURON

FUNCTIONAL CLASSIFICATION

Interneuron- located entirely within CNS, (only in CNS) and connect neurons together

integrates functions in CNS

Sensory neuron: ( signals from sensory receptor to CNS)

Motor neuron: ( signals from CNS to effectors organ)

STRUCTURAL CLASSIFICATIONNeurons display great diversity in size and

shape . Structural classification : according to the number of processes extending from the cell body. A- Mutipolar neurons : - have several dendrites and one axon. - Neurons of brain and spinal cord.

B- Bipolar neurons :- have one dendrite and one axon.- found in the retina of the eyes , in the inner ear and in the olfactory area of the brain

c- Unipolar neurons : - have dendrites and one axon - these neurons are more appropriately called: pseudounipolar neurons because they begin in the embryo as bipolar neurons.unipolar neurons are located in dorsal root ganglia of spinal cor & sensory ganglion of cranial nerves.