How the nervous system is organized
CNS, PNS, and an interactive protective reflex.
The central nervous system (CNS) is the brain and spinal cord — it receives, processes, and coordinates responses. The peripheral nervous system (PNS) is the nerves throughout the body — it carries information between the CNS and everything else. They work together continuously.
Watch: How the CNS and PNS Work Together
Follow a message as it travels from the body to the brain—and back again.
Central nervous system (CNS)
Brain + spinal cord
Receives and processes information and helps coordinate responses.
Peripheral nervous system (PNS)
Nerves throughout the body
Carries information between the CNS and the rest of the body.
Explore the Nervous System
Choose a view to see how the central and peripheral nervous systems are organized.
Select the brain, spinal cord, or peripheral nerves to read what each part does.
- Lavender
- Lavender = Central nervous system
- Teal
- Teal = Peripheral nervous system
Central and peripheral nervous systems shown together.
Follow the Signal: A Protective Reflex
Watch information travel through the nervous system when the body detects something dangerously hot.
What do you predict happens first?
Current stage
Make a prediction, then start the signal to follow it stage by stage.
This is an on-screen simulation. Never test it using a genuinely hot object.
Three Key Takeaways
- 1The nervous system has two main parts: the central nervous system (brain and spinal cord) and the peripheral nervous system (all other nerves).
- 2Signals travel in both directions — sensory nerves carry messages from the body to the CNS, and motor nerves carry commands back to muscles and organs.
- 3Reflexes are fast, protective responses routed through the spinal cord, so the body can react before the brain even processes what happened.