The Human Nervous System
Revise The Human Nervous System for GCSE Biology with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. Trace the full pathway: stimulus, receptor, sensory neurone, central nervous system, motor neurone and finally the effector.
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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
Topic overview
The nervous system enables humans to react to their surroundings and coordinate their behaviour. It consists of the central nervous system — the brain and spinal cord — and the neurones that connect to it.
Information travels as electrical impulses along neurones. A stimulus is detected by receptor cells, which send an impulse along a sensory neurone to the central nervous system. There the information is coordinated, and an impulse travels along a motor neurone to an effector.
The pathway is always the same: stimulus, receptor, sensory neurone, coordinator, motor neurone, effector, response. Being able to write that sequence out reliably answers a large proportion of the questions on this topic.
Revision notes
Structure of the nervous system
The central nervous system consists of the brain and spinal cord.
Sensory neurones carry impulses from receptors to the CNS. Motor neurones carry impulses from the CNS to effectors, which are muscles or glands.
The pathway
Stimulus → receptor → sensory neurone → coordinator (CNS) → motor neurone → effector → response.
Every nervous response follows this sequence. Learning it means you can answer describe-the-pathway questions in any context.
Synapses
Where two neurones meet there is a small gap called a synapse.
The electrical impulse cannot cross the gap, so a chemical is released which diffuses across and triggers a new impulse in the next neurone. This slows the response slightly.
Key points
- The CNS consists of the brain and spinal cord.
- Sensory neurones carry impulses to the CNS.
- Motor neurones carry impulses from the CNS to effectors.
- Effectors are muscles or glands.
- The pathway is stimulus, receptor, sensory, CNS, motor, effector, response.
- At a synapse a chemical diffuses across the gap.
Worked examples
Example 1
Describe the pathway of a nervous response from stimulus to response. [4 marks]
Model answer
A stimulus is detected by a receptor (1 mark). An electrical impulse travels along a sensory neurone to the central nervous system (1 mark), where the information is coordinated (1 mark). An impulse then travels along a motor neurone to an effector, which brings about the response (1 mark).
Example 2
Explain how an impulse passes from one neurone to the next. [3 marks]
Model answer
There is a small gap between the neurones called a synapse (1 mark). A chemical is released from the first neurone and diffuses across the gap (1 mark), triggering a new electrical impulse in the next neurone (1 mark).
Example 3
Name the two parts of the central nervous system. [2 marks]
Model answer
The brain (1 mark) and the spinal cord (1 mark).
Common mistakes
Saying the impulse jumps across the synapse.
It cannot. A chemical diffuses across and triggers a new impulse.
Confusing sensory and motor neurones.
Sensory carries impulses to the CNS; motor carries them from the CNS.
Including nerves in the CNS.
The CNS is only the brain and spinal cord.
Missing steps from the pathway.
All seven stages may be needed; count the marks available.
Exam tips
- Memorise the seven-stage pathway and write it in order.
- Say chemical diffuses across when describing a synapse.
- Name muscles or glands as effectors.
- Use the mark allocation to judge how much detail to give.
Key terms
- Neurone
- A nerve cell that transmits electrical impulses.
- Synapse
- The gap between two neurones.
- Stimulus
- A change detected by a receptor.
- Central nervous system
- The brain and spinal cord.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.