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Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
The key difference
The nervous system uses electrical impulses along neurones for fast, short-lived, precise responses. The endocrine system uses hormones carried in the blood for slower, longer-lasting, widespread responses.
The body uses two communication systems to coordinate its functions. The nervous system handles rapid responses (like reflexes), while the endocrine system handles longer-term regulation (like growth and blood glucose control). Many exam questions ask you to compare these two systems directly.
Feature
Nervous System
Endocrine System
Signal type
Electrical impulses (nerve impulses)
Chemical messengers (hormones)
Transmission route
Along neurones (nerve cells)
Through the bloodstream
Speed of response
Very fast (milliseconds)
Slower (seconds to hours)
Duration of response
Short-lived: stops when impulse stops
Longer-lasting: hormones remain in the blood
Target
Specific: targets individual effectors (muscles or glands) via specific neurones
Widespread or specific: hormones travel everywhere in blood but only affect target organs with the correct receptors
Effector
Muscles and glands
Target organs / tissues
Example
Reflex arc: pulling hand away from a hot object
Insulin release to lower blood glucose after a meal
When Each System Is Used
The nervous system is used when a rapid, short-term response is needed:
Reflexes (pulling hand away from heat)
Voluntary movements (deciding to pick up a pen)
Sensory processing (seeing, hearing, feeling)
The endocrine system is used when a slower, longer-lasting response is needed:
Fight-or-flight response (adrenaline: though this is relatively fast for a hormone)
Adrenaline: The Exception
Adrenaline is a hormone (so it belongs to the endocrine system), but it acts relatively quickly because it is released in large quantities directly into the bloodstream during a "fight-or-flight" response. It causes rapid changes: increased heart rate, dilated pupils, glycogen → glucose conversion in the liver. Some exam questions ask whether adrenaline is "more like" a nervous or hormonal response: the answer is that it is a hormone but it acts faster than most hormones because of the urgency of the fight-or-flight situation.
Try a comparison question (4 marks)
Compare how the nervous system and the endocrine system transmit signals within the body. [4]
Show the answer and marking guidance
The nervous system transmits signals as electrical impulses along neurones; the endocrine system transmits signals as hormones (chemicals) carried in the blood
Nervous responses are very fast (milliseconds); endocrine responses are slower (seconds to hours)
Nervous responses are short-lived and stop when the impulse stops; endocrine responses are longer-lasting as hormones remain in the blood
Nervous responses target specific effectors via specific neurones; endocrine responses affect target organs with the correct receptors, which may be widespread
Original Cambridge-style practice written for this site.
Common comparison mistakes
When answering a compare question, write matched pairs rather than two separate descriptions.
Saying the nervous system uses "chemicals": it uses electrical impulses (though synapses use neurotransmitters to cross the gap)
Claiming hormones affect every cell in the body: they only affect target cells with the correct receptors
Forgetting that both systems can work together (e.g. The brain sends nerve impulses to the adrenal gland, which releases adrenaline: a hormone)
Saying endocrine responses are always slow: adrenaline acts relatively quickly