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Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Key concept
Hormones are chemical messengers produced by endocrine glands and transported in the blood to target organs where they produce an effect. Hormonal control is slower, longer-lasting and more widespread than nervous control. Key endocrine glands include the pituitary, thyroid, adrenal glands and pancreas.
The endocrine system works alongside the nervous system to coordinate body functions. Exam questions often ask you to compare the two systems. Hormones are slower but longer-lasting; nerves are faster but shorter-acting.
How the endocrine system works
Endocrine glands are ductless glands that secrete hormones directly into the bloodstream. Hormones are chemical substances that travel in the blood plasma and affect specific target organs or cells that have the correct receptors.
The effect of a hormone is not immediate: there is a delay as the hormone travels through the circulatory system. However, once a hormone reaches its target, the effect can last for hours, days or even longer.
Key hormones and glands
Gland
Hormone
Function
Pancreas
Insulin
Lowers blood glucose by stimulating cells to take up glucose and liver to convert glucose to glycogen
Pancreas
Glucagon
Raises blood glucose by stimulating liver to convert glycogen to glucose
Adrenal glands
Adrenaline
Prepares the body for fight-or-flight: increases heart rate, breathing rate, blood flow to muscles
Pituitary gland
ADH
Controls water reabsorption in the kidney collecting ducts
Ovaries
Oestrogen, progesterone
Control the menstrual cycle and secondary sexual characteristics
Testes
Testosterone
Controls male secondary sexual characteristics and sperm production
Comparing nervous and hormonal control
Feature
Nervous system
Endocrine system
Signal type
Electrical impulses along neurones
Chemical hormones in the blood
Speed
Very fast (milliseconds)
Slower (seconds to minutes)
Duration
Short-lived
Longer-lasting
Target
Specific (to individual muscles or glands)
Widespread (any cell with the correct receptor)
Pathway
Along neurones
Through the bloodstream
Try a focused question (2 marks)
State two differences between nervous and hormonal coordination.
Show the answer and marking guidance
Nervous coordination uses electrical impulses along neurones and is fast; hormonal coordination uses chemical hormones in the blood and is slower.
Nervous responses are short-lived and targeted to specific effectors; hormonal responses are longer-lasting and can affect many target organs.
Original Cambridge-style practice written for this site. It is not an official Cambridge past-paper question.
Common mix-ups to avoid
Check these points against your own answer before moving on.
Saying hormones travel along nerves: hormones travel in the blood.
Confusing the pancreas (produces insulin) with the pituitary (produces ADH).
Describing hormonal effects as instant: there is a time delay as hormones travel in blood.
Saying hormones affect all cells in the body: only cells with the correct receptors respond.