The Nervous System · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

The Nervous System: Two Parts, One Fast Team

Science · The Human Body · ages 9-11
Name ______________________   Date ____________

  1. Which two body parts make up the central nervous system?

    • Heart and stomach working together
    • Brain and spinal cord
    • Skin and muscles

  2. What are the two main parts of the nervous system?

    • Central and peripheral nervous system
    • Muscles and bones all over your body and face
    • Heart and lungs

  3. Nerves only exist in your brain, not anywhere else in your body.

    Circle one:   True   False

  4. Jay steps on a sharp rock. What is the correct order of his reflex?

    • Stimulus, sensory nerve, spinal cord, motor nerve, muscle moves
    • Muscle moves, motor nerve, spinal cord, sensory nerve, stimulus
    • Sensory nerve, muscle moves, stimulus

  5. In this reflex arc, what happens at the step marked with a question mark?

    Hot touchSense nerve?Motor nerveMove hand
    • The stomach digests food
    • The eyes blink on their own to keep them wet and safe
    • The spinal cord reacts and sends a signal back

  6. Why can you pull your hand off a hot stove before you even feel the full pain?

    • Because your hand moves before your body sends any message at all
    • Because nerve signals travel very fast to and from your spine
    • Because pain travels slower than sound

  7. A doctor taps just below a patient's knee, and the leg kicks out on its own. Which part of the nervous system made that fast, automatic response possible?

    • The peripheral nerves and spinal cord working as a reflex arc
    • Only the muscles, with no nerves involved
    • Only the brain, thinking very carefully about the tap first, not quickly

  8. Zara says: 'My brain has to think about it every time before I blink when something flies at my eye.' What is wrong with what she said?

    • Nothing is wrong, brains always think before every single movement
    • Blinking only happens if the peripheral nervous system is missing from the body
    • Blinking at something flying at your eye is a fast reflex, not a decision
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Answer key

For grown-ups. Fold this page away before handing over the rest.

The Nervous System: Two Parts, One Fast Team W1-mt_qzbgwaUQOA-s1

  1. Brain and spinal cord · Together, the brain and spinal cord form your central nervous system, the body's command center.
  2. Central and peripheral nervous system · The central nervous system is the brain and spinal cord. The peripheral nervous system is the nerves that reach the rest of your body.
  3. False · Nerves branch out from your spinal cord to reach your entire body. That network is called the peripheral nervous system.
  4. Stimulus, sensory nerve, spinal cord, motor nerve, muscle moves · A reflex always starts with a stimulus and ends with the muscle responding, with the sensory nerve, spinal cord, and motor nerve in between.
  5. The spinal cord reacts and sends a signal back · The spinal cord (sometimes with the brain) receives the sensory signal and sends out the motor command instantly.
  6. Because nerve signals travel very fast to and from your spine · Nerve signals move at high speed, so your body can react in a reflex before the pain feeling fully forms in your brain.
  7. The peripheral nerves and spinal cord working as a reflex arc · The knee-jerk reflex is a classic example of a reflex arc: sensory nerves send the signal to the spinal cord, which immediately sends a motor signal back to the muscle.
  8. Blinking at something flying at your eye is a fast reflex, not a decision · Reflexes like blinking use the fast sensory nerve to spinal cord to motor nerve pathway, so your body reacts before your brain fully processes the danger.
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