Hormones and temperature control — Edexcel International GCSE Biology
How nervous and hormonal communication differ, the main hormones and what they do, and temperature control by the skin.
Revision notes
4 short notes, in the order of the specification. Each one in short:
Nervous and hormonal communication both control responses in the body. Nervous communication uses electrical impulses along neurones, is very fast and its effect is short-lived. Hormonal communication uses hormones secreted by endocrine glands directly into the blood, which carries them to target organs. It is slower, but its effect lasts longer.
Hormones are chemicals secreted by glands into the blood. Adrenaline from the adrenal glands prepares the body for fight or flight by increasing heart rate. Insulin from the pancreas lowers blood glucose by making cells take up glucose and the liver store it as glycogen. Testosterone comes from the testes, and oestrogen and progesterone from the ovaries.
ADH, FSH and LH
Biology onlyADH, FSH and LH are three hormones released by the pituitary gland at the base of the brain. ADH makes the collecting ducts of the kidney more permeable to water, so more water is reabsorbed. FSH causes an egg to mature in an ovary and stimulates the ovaries to produce oestrogen. LH stimulates ovulation, the release of the egg.
The skin helps control body temperature. When the body is too hot, sweat glands release sweat, which evaporates and takes heat from the skin, and vasodilation widens blood vessels in the dermis so more blood flows near the surface and more heat is lost. When too cold, little sweat is made and vasoconstriction reduces heat loss.
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Quick check questions
Name two differences between nervous and hormonal communication.
Show answer
Nervous is fast and short-lived using electrical impulses; hormonal is slower and longer-lasting using chemicals in the blood.
Which gland makes insulin?
Show answer
The pancreas.
Where is adrenaline produced?
Show answer
In the adrenal glands.
Biology only What does ADH change in the kidney?
Show answer
It makes the collecting ducts more permeable to water, so more water is reabsorbed.
What happens to skin blood vessels when you are too hot?
Show answer
They widen (vasodilation), so more heat is lost.
Frequently asked questions
Why are hormones called chemical messengers?
Hormones are called chemical messengers because they are chemicals secreted by glands directly into the blood, which carries them to target organs where they cause an effect. Hormonal communication is slower than nervous communication, which uses electrical impulses, but its effects last longer. Hormones reach every part of the body but only affect their target organs.
What does insulin do to blood sugar?
Insulin lowers blood glucose concentration. When blood glucose is high, the pancreas secretes insulin into the blood. Insulin makes cells take up glucose from the blood and makes the liver convert glucose into glycogen for storage, so the blood glucose concentration falls. The pancreas makes insulin, but the liver stores the glycogen.
What does adrenaline do to the body?
Adrenaline prepares the body for fight or flight. It is released by the adrenal glands when a person is frightened or excited. It increases heart rate, so more blood carrying oxygen and glucose reaches the muscles for respiration. It also stimulates the liver to change glycogen into glucose, raising blood glucose.
What does FSH do in the menstrual cycle?
Biology only FSH, released by the pituitary gland, causes an egg to mature in an ovary and stimulates the ovaries to produce oestrogen. FSH does not release the egg: LH, also from the pituitary gland, stimulates ovulation, the release of the egg from the ovary, triggered by a surge in LH around day 14.
How is body temperature regulated by the skin?
The skin regulates body temperature by sweating and by changing blood flow near the surface. When too hot, sweat evaporates and takes heat from the skin, and vasodilation widens blood vessels in the dermis so more heat is lost. When too cold, little sweat is produced and vasoconstriction narrows the vessels, so less heat is lost.
Written and checked against the Edexcel IGCSE Biology (4BI1) specification · Updated October 2026