The document provides an overview of the nervous system and brain structures. It discusses the basic unit of the nervous system, the neuron, and how neurons communicate using neurotransmitters. It describes the central nervous system, made up of the brain and spinal cord, and the peripheral nervous system, including the somatic and autonomic divisions. It also outlines structures in the brain stem that control basic functions, as well as limbic system structures involved in emotion, learning, and memory. Imaging techniques used to study the living brain are also summarized.