Brain
There are dozens of other chemical neurotransmitters that are used in more limited areas of the brain, often areas dedicated to a particular function. Serotonin, for example—the primary target of antidepressant drugs and many dietary aids—comes exclusively from a small brainstem area called the raphe nuclei. Norepinephrine, which is involved in arousal, comes exclusively from a nearby small area called the locus coeruleus. Other neurotransmitters such as acetylcholine and dopamine have multiple sources in the brain, but are not as ubiquitously distributed as glutamate and GABA.
Physiological psychology
The nervous system can be described as a control system that interconnects the other body systems. It consists of the brain, spinal cord, and other nerve tissues throughout the body. The system's primary function is to react to internal and external stimuli in the human body. It uses electrical and chemical signals to send out responses to different parts of the body, and it is made up of the nerve cells also called neurons. Through the system, messages are transmitted to body tissues such as a muscle. There are two major subdivisions in the nervous system known as the central and peripheral nervous system.