Final answer:
The smallest functional unit of the nervous system is a neuron. Neurons are specialized cells that transmit electrical and chemical signals within the nervous system.
Step-by-step explanation:
The smallest functional unit of the nervous system is a neuron. Neurons are specialized cells that transmit electrical and chemical signals within the nervous system. They have a distinct structure, with dendrites receiving signals, a cell body where the signal is integrated, and an axon that transmits the signal to other neurons or target cells.