Chapter 2 the systems of the body. The nervous system is a complex network of interconnected nerve fibres that functions to regulate many important bodily functions, including the response to and recovery from stress. Nervous system = central nervous system and peripheral nervous system. Central nervous system = brain and spinal cord. Peripheral nervous system = rest of the nerves in the body, including those that connect to the brain and spinal cord: the peripheral nervous system is made up of the somatic nervous system and the autonomic nervous system. The somatic nervous system (or voluntary nervous system) connects nerve fibres to voluntary muscles and provides the brain with feedback in the form of sensory information about voluntary movement. The autonomic nervous system (or involuntary nervous system) connects the central nervous system with all internal organs over which people do not have control.