This document provides information about the nervous system and neurons. It discusses that the nervous system controls all body functions and detects internal and external changes. It is comprised of neurons and neuroglia. Neurons consist of a cell body, dendrites, and axon. Neurons can be classified based on their structure as unipolar, bipolar, or multipolar. They can also be classified based on function as motor, sensory, or interneurons. The properties of nerve fibers include excitability, conductivity, all-or-none response, refractory period, summation, adaptation, and lack of fatigability.