The brain, one of nature's most complex systems, is directly responsible for the mental processes and behaviors examined by psychology. The forebrain, midbrain, and hindbrain are the three main sections of the brain, each with many portions. To keep the body running, every component of the brain must work together. The central nervous system, which includes the brain and spinal cord, is in charge of controlling all body functions with the peripheral nervous system. Psychology studies the relationship between mental processes and behavior on a systemic level in order to explain individual mental processes and behavior. The brain is a complicated organ that regulates every action in our body, including thought, memory, emotion, touch, motor skills, vision, respiration, temperature, and hunger. The central nervous system, or CNS, is made up of the brain and the spinal cord that extends from it.