Roles of Nervous System Components

Steps:

• Recall that receptors detect environmental stimuli and transmit impulses to the CNS for processing.
• Identify effectors as muscles or glands that receive impulses from the CNS to produce responses.
• Differentiate CNS (brain and spinal cord) as the processing center from PNS (nerves connecting to body).
• Evaluate each option against these definitions to find the accurate description.

Why D is correct:

• Receptors, by definition, sense changes in the environment (stimuli) and send sensory impulses to the CNS for integration.

Why the others are wrong:

• A: Effectors receive impulses from the CNS to respond, not send them.
• B: The CNS coordinates and transmits impulses to multiple effectors simultaneously via pathways.
• C: The PNS carries impulses from receptors to the CNS and from the CNS to effectors, not "to effectors and receptors from the CNS."

Final answer: D