--- title: "Nerves or hormones?" subtitle: "Year 9 Biology · Coordination and control · Lesson 3" --- # Nerves or hormones? **Name:** {{field-24}} **Date:** {{field-15}} **Class:** {{field-15}} > **Key question:** Pull your hand off a hot pan and you've done it in a fraction of a second. After lunch, your body brings your blood sugar back down too, but that takes an hour. Same job, different messengers. :::teacher-note **In one sentence:** Students describe how the nervous and endocrine systems each run the stimulus–receptor–command centre–effector pathway, and compare their signals, speed, duration and reach (AC9S9U01, node 3). **Students should be able to say:** I can explain how a nerve signal and a hormone each carry a message. I can compare how fast each is and how long it lasts. I can name glands as command centres and target organs as effectors. **Width:** the unmarked parts are the floor every student does (Engage, Explore, Explain, Evaluate). Typical and Wider sections add contexts, not difficulty. Students work in the online tutorial alongside this sheet. ::: ## Engage :::keep-together **After a meal, your pancreas releases insulin, which tells your liver to store glucose. How does the insulin get from the pancreas to the liver?** ☐ Along a nerve ☐ In the blood ☐ Through the stomach ☐ It is made in the liver My prediction, and why: {{lines-3}} ::: :::teacher-note **What happens:** In the blood. Insulin is a hormone: a chemical message released by a gland into the blood, which carries it everywhere; only target organs, such as the liver, respond. ::: ## Explore Try it on the board in the tutorial. Was your prediction right? What was different? {{lines-2}} ## Explain: comparing the two systems :::keep-together ### Nervous or endocrine **Nervous system or endocrine (hormone) system?** Groups: Nervous, Endocrine - Electrical signals along nerves: {{field-15}} - Chemical messages carried in the blood: {{field-15}} - Very fast: a fraction of a second: {{field-15}} - Slower: seconds to hours: {{field-15}} - Short-lived: stops when the signal stops: {{field-15}} - Lasts longer: until the hormone is broken down: {{field-15}} - Goes to one precise place: {{field-15}} - Reaches the whole body; only target organs respond: {{field-15}} ::: :::teacher-note **Answer:** Electrical signals along nerves → Nervous; Chemical messages carried in the blood → Endocrine; Very fast: a fraction of a second → Nervous; Slower: seconds to hours → Endocrine; Short-lived: stops when the signal stops → Nervous; Lasts longer: until the hormone is broken down → Endocrine; Goes to one precise place → Nervous; Reaches the whole body; only target organs respond → Endocrine ::: :::keep-together ### Glands **In a hormonal pathway, what is the command centre?** ☐ The blood ☐ A gland, such as the pancreas, which releases the hormone ☐ The target organ ::: :::teacher-note **Answer:** A gland, such as the pancreas, which releases the hormone Glands (pancreas, adrenal glands, pituitary) act as command centres: they detect or are told of a change and release a hormone. ::: :::keep-together ### Why faster **Why do electrical signals reach their effector faster than hormones?** ☐ Hormones have further to go because glands are far away ☐ They travel along nerves directly to one place; hormones drift around the body in the blood ☐ Electricity is stronger than chemicals ::: :::teacher-note **Answer:** They travel along nerves directly to one place; hormones drift around the body in the blood Nerve signals travel at up to about 100 m/s along a wired route. Hormones go wherever the blood goes, which takes about a minute for one lap of the body, and then must build up. ::: :::keep-together ### Both at once **A fright makes you jump (nerves) and your heart keep pounding for minutes (adrenaline). Why use both?** ☐ Nerves give the instant reaction; the hormone keeps the whole body ready for longer ☐ The nerves stop working after a fright ☐ Adrenaline is a nerve signal ::: :::teacher-note **Answer:** Nerves give the instant reaction; the hormone keeps the whole body ready for longer Fast and short, plus slow and lasting: many responses use both systems. ::: :::typical ## Elaborate: race them :::keep-together ### Reading the graph **On the graph, which response starts first, and which lasts longer?** ☐ The hormone response starts first and lasts longer ☐ The nerve response starts first; the hormone response lasts longer ☐ They start and stop together ::: :::teacher-note **Answer:** The nerve response starts first; the hormone response lasts longer Nerves: fast and brief. Hormones: slow to start, slow to fade. ::: ::: :::wider ## Elaborate: when water is short :::keep-together ### ADH **On a hot day with little to drink, the pituitary gland releases ADH, and the kidneys keep more water. Which is the effector?** ☐ The pituitary gland ☐ The kidneys ☐ ADH ::: :::teacher-note **Answer:** The kidneys Gland (command centre) → hormone in the blood (messenger) → kidneys (effector) → less water lost (response). ::: ::: ## Evaluate: look back Write one sentence: "At first I thought… Now I think… because…" **Revision summary** - Both systems follow stimulus → receptor → command centre → effector → response. - **Nervous system**: electrical signals along nerves, from the brain or spinal cord. Very fast, short-lived, to one place. - **Endocrine system**: hormones released by **glands** (pancreas, adrenal glands, pituitary) into the blood. Slower, longer-lasting, reaching target organs anywhere. - Many responses use both (a fright: a jump from nerves, a pounding heart from adrenaline). ## Exit ticket :::keep-together **Give one difference between how a nerve signal and a hormone travel, and one difference in how long their effects last.** {{lines-3}} ::: :::teacher-note **Answer:** Nerve signals are electrical, along nerves; hormones are chemicals in the blood. Nerve effects are brief; hormone effects last longer. :::