An injury to the nervous system results in nervousness and hyperactivity. which division of the nervous system was damaged by the injury?
central
sympathetic
sensory somatic
parasympathetic

Central nervous system
Sympathetic nervous system

The neuron, a cell that composes the nervous system. For example a brain, an organ composed of thousands of neural fibers and glial cells that performs many important organismic functions. 
Neurons are specialised cells that have dendrites, axons and terminal buttons that sends and receives stimuli from the environment and transduces it into a meaningful information and understand the complexities which the brain now functions.