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The function of the nervous system is detecting changes in the environment and coordinating responses. Free GCSE Biology notes and 14 FAQs.
How the Nervous System Works is part of The human nervous system in GCSE Edexcel Higher Biology.
4 min
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14
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GCSE Edexcel Higher
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The function of the nervous system is detecting changes in the environment and coordinating responses. Free GCSE Biology notes and 14 FAQs.
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Use this lesson to stay inside The human nervous system while connecting the detail back to the wider Topic 2: Cells and control topic.
Read the core explanations from How the Nervous System Works before testing yourself from memory.
Right now, your nervous system is working overtime. It's processing these words, controlling your breathing, and keeping you balanced in your chair. Without it, you'd be unable to react to anything — no pulling your hand away from a hot surface, no catching a falling object.
The nervous system is your body's electrical wiring and control centre. It detects changes in your environment and coordinates responses faster than you can think. This coordination keeps you alive and helps you interact with the world around you.
Picture the nervous system as a motorway network. Information travels along nerve cells called neurones like cars on roads. These electrical impulses carry messages at incredible speeds — up to 120 metres per second.
Neurones are perfectly adapted for their job. They're long and thin to carry impulses over large distances. They have branched endings to connect with other neurones, creating a network that reaches every part of your body.
Trap: Many students think nerve impulses are like water flowing through pipes. Actually, they're electrical signals that jump from one neurone to the next, maintaining their strength throughout the journey.
At the heart of your nervous system sits the Central Nervous System (CNS). This is your body's mission control — the brain and spinal cord working together to process information and coordinate responses.
The brain is the ultimate processor, handling complex decisions and storing memories. The spinal cord acts like a superhighway, carrying messages between the brain and the rest of your body. Together, they make sense of incoming information and decide what to do about it.
Think of the CNS as air traffic control at a busy airport. It receives information from multiple sources, processes it quickly, and sends out clear instructions to keep everything running smoothly.
Every response your body makes follows the same pathway. It's like a relay race where information passes from runner to runner. This pathway ensures you respond appropriately to changes in your environment.
Let's break this down with a real example. You touch a hot pan: the heat (stimulus) is detected by temperature receptors in your skin. These send electrical impulses to your spinal cord and brain (coordinator). Your CNS processes this as 'danger' and sends impulses to arm muscles (effector). Your muscles contract, pulling your hand away (response).
Worked example: Tracing a Response Pathway
A student hears a fire alarm and runs towards the exit. Trace the complete pathway from stimulus to response.
Answer: Sound → ears → CNS → leg muscles → running
The nervous system is a masterpiece of biological engineering. Every part is perfectly designed for its job, like a Formula 1 car where every component serves a specific purpose.
Receptors are specialised for detection — your eyes have light-sensitive cells, your ears have sound-sensitive cells. The CNS is protected by bone (skull and spine) because it's so important. Neurones are insulated to prevent electrical impulses from 'leaking' to the wrong place.
Effectors are built for action. Muscles have protein fibres that can contract rapidly. Glands have cells packed with the machinery to make and release hormones quickly when needed.
Nervous system questions follow predictable patterns. Examiners love testing the stimulus-response pathway and asking you to identify each component. Here's how to guarantee full marks.
Common Exam Trap: Students often write 'nerves' instead of 'neurones'. Nerves are bundles of neurones — like cables containing many wires. Use the precise term for full marks.
Master this pathway and you'll handle any nervous system question with confidence. The key is understanding that every response follows the same logical sequence, whether it's pulling your hand from a flame or your mouth watering at the smell of food.
Published by Revise Right. Use the official specification reference to check the requirements for your course. Content updated: 2026-03-23.
Move to the related lessons or back to the topic page when you need the wider sequence before exam-style practice.
A stimulus is a change in the environment that triggers a response. Stimuli are detected by receptors, such as temperature receptors in the skin detecting the heat of a hot pan.
The function of the nervous system is detecting changes in the environment and coordinating responses. It acts as the body's electrical wiring and control centre, allowing responses such as pulling a hand away from a hot surface.
The central nervous system (CNS) is the brain and spinal cord, which coordinate responses to stimuli. It processes information from receptors and controls all body functions, with the spinal cord carrying messages between the brain and the rest of the body.
The spinal cord acts like a superhighway, carrying messages between the brain and the rest of the body. Together with the brain, it forms the central nervous system, which coordinates responses to stimuli.
Effectors are muscles and glands, the organs that produce a response to a stimulus. Muscles contract, using protein fibres that can contract rapidly, and glands secrete hormones.
A receptor is a cell or organ that detects changes in the environment (stimuli) and converts them into electrical impulses sent to the CNS. An effector is an organ that produces a response to a stimulus, either muscles that contract or glands that secrete hormones.
Hearing a fire alarm and running to the exit is an example of a stimulus and response. The sound is the stimulus, the ears are receptors, the CNS coordinates, the leg muscles are effectors, and running is the response.
Every response follows the pathway stimulus → receptor → coordinator (CNS) → effector → response. For example, heat from a hot pan is detected by temperature receptors in the skin, the CNS processes it, and arm muscles contract to pull the hand away.
A neurone is a nerve cell that carries electrical impulses around the body and transmits information between receptors, the CNS and effectors. Neurones are long and thin to carry impulses over large distances and have branched endings to connect with other neurones.
A neurone is a single nerve cell, while a nerve is a bundle of neurones, like a cable containing many wires. In exams, use the precise term neurone rather than nerve when describing how impulses are carried.
A receptor is a cell or organ that detects changes in the environment (stimuli) and converts them into electrical impulses sent to the CNS. Eyes have light-sensitive cells and ears have sound-sensitive cells.
The central nervous system is protected by bone, the skull and spine, because it is so important. The brain and spinal cord process information from receptors and control all body functions.
Neurones are long and thin to carry electrical impulses over large distances, and they have branched endings to connect with other neurones. They are also insulated to prevent impulses from leaking to the wrong place.
The coordinator in the nervous system is the CNS, the brain and spinal cord. It receives electrical impulses from receptors, processes the information and sends impulses to effectors to produce a response.