What system consists of the brain and spinal cord, controlling body actions?

The central nervous system (CNS) is comprised of the brain and spinal cord, serving as the primary control center for the body. It processes sensory information, controls motor functions, and is responsible for higher cognitive functions such as reasoning and emotional responses. The brain interprets input from the senses and formulates responses through the spinal cord, which relays messages between the brain and the rest of the body.

Understanding the structure and function of the central nervous system is crucial in many fields, including esthetics, because it helps practitioners comprehend how various treatments can affect clients both physically and emotionally. For example, certain esthetic treatments may influence a client's nervous system responses, which can impact their level of relaxation or stress.

The other systems mentioned play different roles in the body. The autonomic nervous system regulates involuntary functions like heart rate and digestion but does not encompass the brain and spinal cord. The peripheral nervous system extends beyond the central nervous system to transmit signals to and from the limbs and organs. The sympathetic nervous system is a division of the autonomic nervous system that specifically prepares the body for 'fight or flight' responses, but it too does not include the primary structures that define the central nervous system.