Nervous signalling uses electrical impulses along neurones, while hormonal signalling uses chemicals carried in the blood. The nervous system is fast and short-lived, and the hormonal system is slower and longer-lasting.
Exam questions ask you to compare them, or to decide which system is involved in a given response. This lesson is part of coordination and responses, and it builds on tracing a reflex pathway.
How do the two systems differ?
| Feature | Nervous system | Hormonal system |
|---|---|---|
| Type of signal | Electrical impulses (and neurotransmitters at synapses) | Chemical hormones |
| Route | Along neurones | In the blood |
| Speed | Very fast | Slower |
| Duration of effect | Short | Longer |
| Spread | Specific target | Reaches the whole body, acts on target organs |
| Example | Reflex withdrawal of a hand | Adrenaline preparing the body for action |
Notice that the word “hormone” is always tied to the blood and to a gland that produces it.
Worked example
Decide which system is mainly responsible for each response and give one reason.
(a) A cyclist swerves away from a pothole in a fraction of a second.
(b) During a frightening event, the heart beats faster and stays fast for several minutes.
Part (a): this is a nervous response. The signal is fast, it travels along neurones, and the effect is short and specific.
Part (b): this is a hormonal response, involving adrenaline. Adrenaline is released into the blood from a gland, travels around the body and acts on the heart. The effect lasts longer than an impulse.
Comparison sentence: the nervous response in (a) is faster and shorter, whereas the hormonal response in (b) is slower to start but lasts longer.
Real situations often involve both systems together. Questions usually ask which one is mainly involved.
The mistake to watch for
A typical answer is: “Nerves are fast. Hormones are in the blood.” That is two facts but no comparison.
Mistaken answer: “Nerves use neurones. Hormones travel in blood. Both send messages.”
There is no contrasting feature such as speed or duration, so the point is not compared.
The correction is to join the two systems with a word such as “whereas” and to use the same feature on both sides: speed with speed, duration with duration.
Check yourself
1. Give two differences between nervous and hormonal communication.
Show answer
Any two matched pairs, for example: nerves use electrical impulses whereas hormones are chemicals; nerves act quickly whereas hormones act more slowly; nerve effects are short whereas hormone effects last longer.
2. Which system carries a hormone to its target?
Show answer
The blood (circulatory system).
3. Insulin is released after a meal and its effects last a while. Is this nervous or hormonal, and why?
Show answer
Hormonal. Insulin is a hormone, carried in the blood, and its effect is longer-lasting than a nerve impulse. The control of blood glucose continues in negative feedback loops.
Where this leads next
Plant responses use chemical signals too, which you can investigate in a simple tropism investigation.
If you tend to write facts instead of comparisons, it may help to practise with a teacher who can mark your wording. Our page on online one-to-one Biology tuition explains how the paid one-hour trial works.