Q. What do you mean by Nervous System?

Structural Organization:  CNS + PNS

Functional Organization:  only concerned with PNS

Sensory (Afferent) ->  CNS

Motor (Efferent)    <-  CNS

Nervous Tissue: 

Two principal tissues:  Neurons and Supporting Cells (Neuroglia)            

• Neurons: Highly specialized to transmit messages (impulses). Vary greatly in shapes, however share common features. These include Dendrites, Cell Body, Axons, and Axon Terminals
• Glia: Different types of cells that generally support, insulate, and protect the delicate neurons. Note that glia still divide during adult life (Gliomas/brain tumors). Some of these cells form the myelin layer, others make CSF.