This deep dive covers Adrenaline and Thyroxine: Two Hormones, Two Timescales within Hormones & Behaviour for GCSE Biology. Topic 8: Hormones & Behaviour It is section 2 of 10 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Adrenaline and Thyroxine: Two Hormones, Two Timescales
This topic focuses on two specific hormones that illustrate how the endocrine system can operate on very different timescales:
- Adrenaline (from the adrenal glands, above the kidneys) — acts within seconds, triggers dramatic physical changes, and is broken down quickly once the threat passes.
- Thyroxine (from the thyroid gland, in the neck) — acts over hours, days, and years to regulate the baseline speed of metabolism throughout the body.
Both are studied as key examples of hormonal control. For the full overview of all endocrine glands and the general endocrine system, see Topic 4: The Human Endocrine System.
Practice questions for Hormones & Behaviour
Which response does adrenaline prepare the body for?
State two effects of adrenaline on the body during a fight-or-flight response.
Quick recall flashcards
Name three effects of adrenaline on the body.
1. Increases heart rate (more blood to muscles).
2. Raises blood glucose levels (provides energy).
3. Dilates pupils and increases breathing rate (heightens alertness).
What is adrenaline and what does it do?
Adrenaline is a hormone released by the adrenal glands (on top of the kidneys) during stress or danger. It prepares the body for 'fight or flight' — increasing heart rate and releasing glucose for energy.