AQA Biology 4.5.2.1 · Combined 4.5.2
The nervous system
A message from your fingertip reaches a muscle in a fraction of a second. Cut one link and see what fails.
Combined Science · Foundation tier
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Hot pan handle.
You grab a pan handle that turns out to be hot, and let go straight away.
If you had to guess, does the message travel through your body as electricity in nerves, or in your blood?
The nervous system
Receptor to effector.
The nervous system lets you react to your surroundings and coordinate your behaviour. Information from receptors passes along neurones as electrical impulses to the central nervous system (CNS): the brain and spinal cord. The CNS coordinates the response of effectors: muscles contracting or glands secreting hormones. Tap each type of neurone.
Now cut one link and predict what is lost.
Receptor, sensory neurone, CNS, motor neurone, effector: the muscle contracts and the hand lets go.
Synapses
Across the gap.
Neurones are not joined end to end. Where two meet there is a tiny gap, a synapse. An electrical impulse can’t cross it: a chemical carries the signal across. Step through.
An electrical impulse travels along the first neurone.
Nerve impulses travel along neurones; hormones travel in the blood and are slower: The endocrine system. Some drugs and alcohol slow the nervous system and increase reaction time: Reaction time.
Think again · jumping the gap?
“The electrical signal jumps across to the next nerve.”
Your call
ChooseHow does the signal get from one neurone to the next?
Sort
Which neurone?
Place each one.
Tap a card, then tap the box it belongs in. Tap a placed card to take it back.
Command words in this lesson
- Describe
- The pathway from receptor to effector, in order.
- Explain
- How a signal crosses a synapse, link by link.
- Use the data
- Read a table about the nervous system and say what it shows.
Key fact
Electrical impulses travel along neurones: sensory to the CNS, relay within it, motor to the effector. A chemical crosses each synapse.
Key note · AQA 4.5.2.1 (Combined 4.5.2)
The nervous system
- The nervous system lets you react to your surroundings and coordinate behaviour.
- CNS = brain and spinal cord. Information travels along neurones as electrical impulses.
- Stimulus, receptor, sensory neurone, CNS (relay), motor neurone, effector (muscle contracts or gland secretes), response.
- A synapse is a gap: a chemical is released, diffuses across and starts a new impulse.
Photograph this card. Tomorrow, cover it and say each line first.
Previous and next
Connects to
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Not sure which way each neurone carries impulses?
Figures are schematic. Response-time data in the practice are made up for teaching.