The Nervous System
Nerves carry electrical signals between the brain and body.
About this topic
The nervous system detects stimuli and coordinates responses rapidly using electrical impulses. The central nervous system (CNS) is the brain and spinal cord, and the peripheral nervous system (PNS) is the nerves linking them to the body, split into sensory and motor neurons.
The somatic system controls voluntary movement; the autonomic system controls involuntary actions like heart rate, with sympathetic ("fight or flight") and parasympathetic ("rest and digest") parts. Signals travel at up to 120 m/s.
When you touch a hot cup, receptors in the skin send impulses along sensory neurons to the spinal cord and brain, which signal motor neurons to muscles that pull away. The system has a voluntary part, which you consciously control, and an autonomic part, which controls heart rate and digestion automatically. The autonomic system has sympathetic fight-or-flight and parasympathetic rest-and-digest branches.
Impulses travel up to about 100 metres per second in fast myelinated nerves. Damage to the spinal cord can cut communication between brain and body, causing paralysis. Compared with hormones, nerves give fast, short, localised responses. Students often think the nerves are single long cells from toe to brain; the path is a chain of neurons linked by synapses.
Key ideas
- CNS: brain and spinal cord
- PNS: nerves
- Sensory, relay and motor neurons
Quick check
Use cases: where The Nervous System helps
- Homework: review the key idea behind The Nervous System before you start a problem set.
- Exam revision: use the quick check to test whether you can recall The Nervous System without notes.
- Visual learning: play with the interactive lab to see how The Nervous System changes when you adjust its inputs.
- Teaching a friend: explain The Nervous System in your own words, then compare your version with the key ideas.
Biology underpins medicine, farming, conservation and biotechnology.
Frequently asked questions
What is The Nervous System?
Nerves carry electrical signals between the brain and body.
What will I learn in The Nervous System?
CNS: brain and spinal cord. PNS: nerves. Sensory, relay and motor neurons.
Is The Nervous System part of Biology?
Yes. It is one of 150 Biology topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the The Nervous System lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study The Nervous System?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.