Human Nervous System (simple) — free printable diagram

What a nervous system diagram shows

The nervous system carries information around the body as electrical impulses, and it is divided into two parts. The central nervous system is the brain and the spinal cord, where information is processed; the peripheral nervous system is the network of nerves branching out from the spinal cord to every other part of the body. A full-body diagram is drawn to show that branching reach.

Two main divisions

Central nervous system (CNS) and peripheral nervous system (PNS)

Central nervous system

The brain and the spinal cord

Peripheral nervous system

All the nerves branching to the rest of the body

Brain

Processes information and coordinates the body

Spinal cord

Carries impulses between the brain and the body

Nerves

Bundles of neurones

Neurone

A nerve cell that carries electrical impulses

Receptors

Detect a stimulus — in the eyes, ears, skin and elsewhere

Effectors

Muscles and glands that carry out the response

• The pathway is worth learning as a sequence: stimulus, receptor, sensory neurone, central nervous system, motor neurone, effector, response. Every example in this topic is a version of that chain.
• Sorting the labelled parts into CNS and PNS is the main exercise the diagram supports: brain and spinal cord in one group, every nerve in the other.
• A reflex is fast because it does not wait for the brain. The impulse travels into the spinal cord and straight back out to the muscle, which is why pulling your hand from something hot happens before you feel the pain.
• The central nervous system is the part encased in bone — the brain in the skull, the spinal cord in the vertebrae — which is a useful clue for remembering which parts belong to it.
• Nerves are not single cells. A nerve is a bundle of many neurones, in the same way a cable is a bundle of wires.
• The body has a second coordination system, the hormonal one, and the two are usually contrasted: nervous signals are electrical and very fast but short-lived, hormonal signals are chemical, slower and longer-lasting.