Hormonal Coordination

Hormonal coordination is how the body uses hormones to control and regulate key processes like growth, metabolism, and reproduction. Learn about the endocrine system, the role of glands and hormones, and how they work together to keep the body in balance — including controlling blood sugar levels, managing the menstrual cycle, and how hormones are used in contraception and fertility treatments.

Practicals on this page:
Plant Growth

The Endocrine System and Hormones

The endocrine system is a collection of glands that produce hormones—chemical messengers that travel through the bloodstream to control various body functions. Unlike the nervous system, hormonal responses are usually slower but last longer.

Controlling Blood Glucose Levels and Diabetes

The hormone insulin, produced by the pancreas, helps regulate blood glucose levels. After eating, insulin causes cells to absorb glucose for energy or storage, lowering blood sugar.

If the body doesn’t produce enough insulin or cells stop responding properly, this leads to diabetes, a condition where blood glucose levels stay too high and can cause serious health problems.

Treatment includes insulin injections or lifestyle changes.

Puberty and the Menstrual Cycle

During puberty, hormones trigger physical changes like growth, development of sexual characteristics, and reproductive maturity.

In females, the menstrual cycle is controlled by hormones such as oestrogen and progesterone, which regulate the release of eggs and prepare the uterus for pregnancy.

Fertility Control and IVF

Hormones can also be used for fertility control:

• Contraception uses hormones (e.g., in the pill) to prevent ovulation and pregnancy.
• In vitro fertilisation (IVF) helps couples conceive by fertilising eggs outside the body before implanting them in the uterus.

Other Important Hormones

• Adrenaline is released in emergencies, increasing heart rate and energy supply as part of the “fight or flight” response.
• Thyroxine, produced by the thyroid gland, controls metabolism, growth, and development.

Plant Hormones and Their Commercial Uses

Plants also use hormones to control growth and responses:

• Auxins help plants grow towards light and control rooting of cuttings.
• Gibberellins encourage seed germination and flowering.
• Ethene promotes fruit ripening.

Commercially, plant hormones are used in agriculture to:

• Help produce seedless fruit
• Control ripening during transport
• Promote rooting in plant cuttings

Also see Reproduction, Genetics, Variation & Evolution

PRACTICAL - Plant Growth

In this required practical, you investigate how light or gravity affects the direction of plant growth, known as tropisms. You’ll usually grow seedlings and observe how they respond to light from one direction (phototropism) or gravity (gravitropism).

This experiment shows how plant hormones like auxins control growth, helping the plant adapt to its environment. It helps you understand how plants grow towards light and against gravity to survive and thrive.

Links for Learning

Bitesize: The human endocrine system
Revision World: Hormones
Bitesize: Hormones in human reproduction
Bitesize: Plant hormones
Bitesize: The human endocrine system test
Bitesize: Hormones in human reproduction test
Bitesize: Plant hormones test