Explain why the hormonal response to a stressor is slower to begin but longer lasting than the nervous system response to the same stressor.

OCR A-Level Biology A (H420) — 5.4 Hormonal communication · Explain · 4 marks · View as Markdown

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

During a stressful event, both the nervous system and the endocrine system are activated. Adrenaline is released from the adrenal medulla and cortisol is released from the adrenal cortex in response to stress.

Model answer (4 marks)

1. Nervous impulses travel along neurones at high speed, whereas hormones must be secreted into the blood and transported to the target organ, which takes more time.
2. Hormones persist in the blood and are not broken down immediately, so their effect is prolonged.
3. Nerve impulses cease immediately when the neurone stops firing; the neurotransmitter is rapidly broken down or re‑absorbed at the synapse.
4. Hormones act on many/widespread target cells simultaneously, whereas nerve impulses act on specific effectors only.

Examiner tips

Use the word ‘because’ to link cause and effect; mention speed of nerve conduction vs blood transport.
Show that hormones are released into circulation, giving a delayed but sustained signal.
Highlight rapid termination of nerve signals by re‑uptake or enzymatic breakdown.
Explain the difference in target cell specificity between nerves and hormones.

Common mistakes

Confusing the timing of hormone release with the duration of action; they are separate.
Failing to mention that hormones act on multiple cells, not just one specific effector.
Using vague terms like ‘slow’ and ‘fast’ without explaining the underlying mechanisms.

Mark scheme (4 marks)

Nervous impulses travel along neurones at high speed / hormones must be secreted into the blood and transported to the target organ, which takes more time
Hormones persist in the blood / are not broken down immediately, so their effect is prolonged
Nerve impulses cease immediately when the neurone stops firing / the neurotransmitter is rapidly broken down or re-absorbed at the synapse
Hormones act on many/widespread target cells simultaneously whereas nerve impulses act on specific effectors only

Key terms in this question

hormonal response · nervous system response · stressor