Neurons serve as the structural and functional units of the human nervous system. A neuron consists of a cell body and its processes, an axon, and one or more dendrites. Neurons initiate and conduct electrochemical impulses. In addition, brain cells influence other cells by secreting neurotransmitters that alter the affected cell by direct contact; alternatively, neurons may release neurohormones into the bloodstream. Medical nanorobots capable of cell repair can restore function to damaged neurons and errant synaptic junctions. Other classes of nanorobots could monitor or even modify neuroelectric and neurochemical traffic in the brain.