A person is extremely frightened after nearly being involved in a road accident. Explain how adrenaline prepares the body to respond to this situation.

OCR GCSE Biology A: Gateway Science (J247) — B3.3 Maintaining internal environments · Explain · 4 marks · View as Markdown

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

The adrenal glands release adrenaline in response to stressful or frightening situations. This is often called the 'fight or flight' response.

Model answer (4 marks)

Adrenaline released from the adrenal glands causes a rapid increase in heart rate, allowing more blood to be pumped to the muscles and vital organs.
Adrenaline also stimulates the lungs to increase breathing rate, ensuring a greater supply of oxygen to the bloodstream.
It raises blood glucose levels by signalling the liver to convert stored glycogen into glucose, which is then released into the blood.
The increased glucose supply provides extra energy for the muscles, enabling a swift physical response to the threat.

Examiner tips

  • Use the exact terminology: adrenaline, heart rate, breathing rate, blood glucose, glycogen conversion. Show the causal chain: adrenaline → physiological changes → preparedness. Keep each point brief but complete to match the 4 marks.
  • common_mistakes
  • :
  • Confusing adrenaline with cortisol or omitting the glycogen‑to‑glucose step. Using vague phrases like "body gets ready" instead of specific physiological actions.

Mark scheme (4 marks)

  1. Adrenaline increases heart rate
  2. Adrenaline increases breathing rate
  3. Adrenaline raises blood glucose levels / increases glucose available to muscles
  4. This is achieved by converting glycogen into glucose

Key terms in this question

adrenaline

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