What are three functions of the nervous system?

• A. Hormone release, digestion, respiration
• B. Memory, learning, emotion
• C. Sensory input, integration, motor output
• D. Reflex actions only

Answer: (C)

The nervous system’s job can be understood in three broad steps: sensing, processing, and responding. Sensory input means receptors detect changes in the body and environment and send signals to the brain and spinal cord. Integration is where those signals are interpreted, memories and experiences are used, and a plan is formed. Motor output is the command sent to muscles or glands to carry out an action, which can be voluntary or automatic (like a reflex). This framework—detect, interpret, respond—best captures how the nervous system operates.

The other options mix processes that aren’t the general functional categories of the nervous system. Hormone release, digestion, and respiration involve other body systems (or autonomic aspects) beyond the core sensory–processing–response roles. Memory, learning, and emotion are brain functions but aren’t the broad functional triplet describing how the nervous system operates. Refex actions are examples of motor output, but they’re too narrow to define the system’s overall functions.