Explain how the hormone adrenaline prepares the body for a 'fight or flight' response.

Eduqas GCSE Biology — 4.2 Hormonal coordination and control in humans · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

When a person encounters a sudden threat, the adrenal glands release the hormone adrenaline into the bloodstream.

Model answer (4 marks)

Adrenaline is released from the adrenal glands into the bloodstream.
Adrenaline increases heart rate.
Adrenaline causes more blood, oxygen and glucose to be delivered to the muscles, allowing faster reaction and movement.
Adrenaline increases the availability of glucose, for example by stimulating the conversion of glycogen to glucose, to provide more energy for respiration.

Examiner tips

  • Use the exact wording from the mark scheme (e.g. "increase heart rate", "more blood/oxygen/glucose to muscles").
  • Show the causal chain: release → effect → physiological outcome.
  • Keep each point brief and separate them clearly.

Common mistakes

  • Confusing adrenaline with cortisol or other hormones.
  • Failing to mention the conversion of glycogen to glucose as a source of glucose.
  • Using vague terms like "more energy" without specifying glucose or oxygen.

Mark scheme (4 marks)

  1. Adrenaline is released from the adrenal glands (into the bloodstream)
  2. Adrenaline causes an increase in heart rate
  3. More blood / oxygen / glucose is delivered to muscles (allowing faster reaction / movement)
  4. Adrenaline increases the availability of glucose (e.g. by causing glycogen to be converted to glucose) to provide more energy for respiration

Key terms in this question

adrenaline · fight or flight

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