Hormones and blood glucose — Edexcel GCSE Biology revision

Endocrine system

• Hormones are chemical messengers carried in the blood; slower but longer lasting than nerves.
• The pituitary is the 'master gland' — it releases hormones that control other glands.

Blood glucose control

• High glucose → pancreas releases insulin → liver and muscles store glucose as glycogen.
• Low glucose → pancreas releases glucagon → glycogen converted back to glucose.
• Type 1 diabetes: pancreas produces too little insulin; treated with insulin injections.
• Type 2 diabetes: body cells stop responding to insulin; linked to obesity, treated with diet and exercise.

Key terms

Hormone

Chemical messenger secreted by a gland into the blood.

Glycogen

Storage carbohydrate made in the liver and muscles.

Negative feedback

A change triggers a response that reverses it.

Ovulation

The release of a mature egg from the ovary.

Menstrual cycle

The approximately monthly cycle of changes in the female reproductive system.

Fertility treatment

Use of hormones (e.g. FSH, LH) to stimulate egg production when a couple struggles to conceive.

Common exam traps

• Writing 'glucagon' when you mean 'glycogen'.
• Saying Type 2 diabetes is treated with insulin as the first option.
• Confusing insulin (lowers glucose) with glucagon (raises glucose) — they sound similar but do opposite jobs.

Practice questions with answers

1. 1. Which organ monitors and controls blood glucose concentration?

   • • Liver
   • • Pancreas
   • • Kidney
   • • Pituitary

   Answer: Pancreas

   It detects the level and releases insulin or glucagon.

2. 2. Describe what happens when blood glucose rises after a meal.

   Answer: The pancreas releases insulin; glucose moves into liver and muscle cells and is stored as glycogen, lowering blood glucose.

   Insulin → storage as glycogen → level falls.

3. 3. State one difference between Type 1 and Type 2 diabetes.

   Answer: Type 1: too little insulin produced. Type 2: cells no longer respond well to insulin.

   A clear contrast is needed for the mark.

4. 4. Which gland is often called the 'master gland'?

   • • Pancreas
   • • Pituitary gland
   • • Thyroid
   • • Adrenal gland

   Answer: Pituitary gland

   It releases hormones that control the activity of many other glands.

5. 5. Explain what negative feedback means, using blood glucose as an example.

   Answer: A rise in blood glucose triggers insulin release which lowers it back towards normal; a fall triggers glucagon which raises it — the response reverses the original change.

   Negative feedback returns a level to normal.

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