GCSE Biology · AQA 8461 · Topic 4.5.3
Hormonal coordination in humans
Key points
- Hormones are made by endocrine glands and travel in the blood. The pituitary is the 'master gland' that controls other glands.
- Blood glucose: the pancreas releases insulin when glucose is high (cells take it up; the liver stores it as glycogen) and glucagon when it is low.
- Type 1 diabetes: no insulin made; treated with injections. Type 2: cells stop responding to insulin; linked to obesity and treated with diet and exercise.
- The kidneys filter blood and reabsorb useful substances. ADH from the pituitary makes them reabsorb more water. Kidney failure is treated by dialysis or a transplant.
- Adrenaline prepares the body for 'fight or flight'; thyroxine controls metabolic rate, using negative feedback.
- Menstrual cycle: FSH matures an egg, oestrogen builds the uterus lining, LH triggers ovulation, progesterone maintains the lining. Contraception may be hormonal or non-hormonal.
- IVF uses FSH and LH to collect eggs, which are fertilised in a lab; it has low success rates and raises ethical issues.
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Hormones are chemical messengers carried in the blood. This sub-topic covers the endocrine system and the hormones that control blood glucose, water balance, reproduction and metabolism.
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