How do hormones control the body, and how is blood glucose kept steady?
Hormones as chemical messengers carried in the blood, the control of blood glucose by insulin, the difference between type 1 and type 2 diabetes, the role of adrenaline, and the difference between nervous and hormonal control.
A focused CCEA GCSE Biology answer on hormones and homeostasis, covering hormones as chemical messengers, the control of blood glucose by insulin, type 1 and type 2 diabetes, adrenaline, and how nervous and hormonal control differ.
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What this dot point is asking
CCEA wants you to explain that hormones are chemical messengers carried in the blood, describe how insulin controls blood glucose, distinguish type 1 and type 2 diabetes, describe the role of adrenaline, and compare nervous and hormonal control.
Hormones as chemical messengers
Controlling blood glucose
The pancreas keeps blood glucose steady, an example of homeostasis (keeping internal conditions constant). When blood glucose is too high (after a meal), the pancreas releases insulin, which makes cells take up glucose and the liver convert glucose to glycogen for storage, so the level falls. When glucose is too low, the liver releases glucose back into the blood.
Diabetes
Adrenaline and homeostasis
Adrenaline is released from the adrenal glands in fear or excitement. It raises the heart rate and breathing rate and releases glucose, preparing the body for "fight or flight". Homeostasis keeps conditions such as blood glucose, temperature and water steady, often by negative feedback (a change triggers a response that reverses the change).
Examples in context
Example 1. Why a type 1 diabetic injects insulin before eating. A person with type 1 diabetes cannot make insulin, so after a meal their blood glucose would rise to dangerous levels. By injecting insulin, they replace the missing hormone, so their cells take up glucose and the level is controlled. They must match the dose to the food and activity, because too much insulin would make their glucose fall too low. This shows insulin is the key control hormone for blood glucose.
Example 2. Adrenaline before a race. Just before a sprint, the adrenal glands release adrenaline. It raises the heart rate so more oxygen and glucose reach the muscles, raises the breathing rate, and releases stored glucose for respiration. The runner feels their heart pounding. This prepares the body for sudden activity, the classic "fight or flight" response, and is a clear example of a hormone producing a coordinated, whole-body change.
Try this
Q1. Name the organ that releases insulin. [1 mark]
- Cue. The pancreas.
Q2. Give two differences between nervous and hormonal control. [2 marks]
- Cue. Nervous is electrical, fast and short-lived; hormonal is chemical, slower and longer-lasting.
Exam-style practice questions
Practice questions written in the style of CCEA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
CCEA 20205 marksExplain how blood glucose concentration is reduced after a meal.Show worked answer →
Five marks for the receptor, the gland, the hormone and the effects.
After a meal, the blood glucose concentration rises as glucose is absorbed from the gut.
The pancreas detects the rise and releases the hormone insulin into the blood.
Insulin travels to the liver and body cells and makes them take up glucose from the blood.
In the liver, insulin causes excess glucose to be stored as glycogen.
As a result, the blood glucose concentration falls back to normal.
Markers reward the pancreas detecting the rise, insulin released, cells take up glucose, liver stores it as glycogen, glucose falls. This is negative feedback.
CCEA 20194 marksCompare nervous control and hormonal control of the body.Show worked answer →
Four marks for clear contrasts, ideally as paired points.
Nervous control uses electrical impulses carried along neurones; hormonal control uses chemicals (hormones) carried in the blood.
Nervous responses are very fast and short-lasting; hormonal responses are slower but longer-lasting.
Nervous control acts on a precise target (a specific muscle or gland); hormones travel everywhere in the blood and act on target organs.
Markers reward at least two correct contrasts: electrical versus chemical, fast versus slow, short-lived versus long-lived, precise versus widespread.
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Sources & how we know this
- CCEA GCSE Biology specification — CCEA (2017)