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# Nerves or hormones?

Year 9 Biology · Coordination and control

<!-- Speaker note: 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). About 25 minutes (Engage and Explore 9 min · Explain 10 min · Evaluate 3 min · Typical adds 3 min, Wider about 3 min). -->

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## Today

**We are learning to** the body runs the same stimulus–receptor–command centre–effector pathway in two ways. The nervous system sends electrical signals along nerves: fast, short and to one place. The endocrine system sends hormones from glands in the blood: slower, longer-lasting and to target organs anywhere.

- 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.

<!-- Speaker note: Before class: A concept tutorial for introducing or revising the idea. Set the width with `?width=minimum`, `typical` (default) or `wider`. It sits between Who decides? (the pathway, node 2) and Nerve or hormone? (comparing the systems in context, node 4), which uses the race board in more depth. Not a hinge node, but students often think every response runs through nerves, or that hormones travel along nerves. The prediction tests the second. Board notes: the pathways are simplified to five boxes. In the glucose pathway the pancreas both detects the change and releases insulin; in the fright pathway the brain triggers the adrenal glands by a nerve. The race graph is a sketch of the timescales, not measured data. Teacher: In your own words: the two five-box pathways with the messenger labelled are the evidence. -->

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## Why it matters

> 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.

<!-- Speaker note: Last lesson: every response runs stimulus → receptor → command centre → effector → response. This lesson: the two ways the message is sent. -->

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<span style="background:#dbeafe; color:#1a1a1a; border:1.5px solid #3b82f6; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">💬 Discussion</span>

## Engage: predict

**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

<!-- Speaker 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. Take two or three predictions before anyone runs it. -->

<!-- Speaker note: Teacher: tally the predictions. 'Along a nerve' is the misconception to come back to. -->

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## Explore it

{{embed: https://studio.learningwaypoints.com/tutorials/_playground-board/index.html?id=deck%2Fscience%2Fbiology-9%2Fsignals%2Fstep-2&code=widget%3A+coordination%0Amode%3A+pathway%0Astimulus%3A+Touching+a+hot+pan+%7C+external+%7C+Heat+receptors+in+the+skin+%7C+Spinal+cord+%7C+Arm+muscles+%7C+You+pull+your+hand+away%0Astimulus%3A+Blood+glucose+rises+after+a+meal+%7C+internal+%7C+Glucose+receptors+in+the+pancreas+%7C+Pancreas+%28releases+insulin%29+%7C+Liver+%7C+The+liver+stores+glucose%0A&fresh=1}}

[Open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/science/biology-9/signals/?full=step-2#step-2)

<!-- Speaker note:  -->

<!-- Speaker note: Teacher: ask what kind of thing sat in the command centre box for each pathway. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## What happened?

* 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.

<!-- Speaker note: Reveal after running. Ask who predicted it, and what made them think so. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Nervous or endocrine

**Nervous system or endocrine (hormone) system?**

Groups: Nervous · Endocrine

Electrical signals along nerves · Chemical messages carried in the blood · Very fast: a fraction of a second · Slower: seconds to hours · Short-lived: stops when the signal stops · Lasts longer: until the hormone is broken down · Goes to one precise place · Reaches the whole body; only target organs respond

* 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

<!-- Speaker note:  -->

<!-- Speaker note: Teacher: the sort is the success criterion; the 'why faster' question is the reason. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## 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

* Answer: A gland, such as the pancreas, which releases the hormone

<!-- Speaker note: Glands (pancreas, adrenal glands, pituitary) act as command centres: they detect or are told of a change and release a hormone. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## 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

* Answer: They travel along nerves directly to one place; hormones drift around the body in the blood

<!-- Speaker note: 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. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## 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

* Answer: Nerves give the instant reaction; the hormone keeps the whole body ready for longer

<!-- Speaker note: Fast and short, plus slow and lasting: many responses use both systems. -->

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<span style="background:#fef3c7; color:#1a1a1a; border:1.5px solid #f59e0b; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✍️ Activity</span>

## Elaborate: race them

{{embed: https://studio.learningwaypoints.com/tutorials/_playground-board/index.html?id=deck%2Fscience%2Fbiology-9%2Fsignals%2Fstep-4&code=widget%3A+coordination%0Amode%3A+race%0A&fresh=1}}

[Open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/science/biology-9/signals/?full=step-4#step-4)

<!-- Speaker note: What this step is for: Seeing the two responses to one fright on a time graph turns 'faster' and 'lasts longer' into shapes to read. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## 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

* Answer: The nerve response starts first; the hormone response lasts longer

<!-- Speaker note: Nerves: fast and brief. Hormones: slow to start, slow to fade. -->

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<span style="background:#fef3c7; color:#1a1a1a; border:1.5px solid #f59e0b; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✍️ Activity</span>

## Elaborate: when water is short

{{embed: https://studio.learningwaypoints.com/tutorials/_playground-board/index.html?id=deck%2Fscience%2Fbiology-9%2Fsignals%2Fstep-5&code=widget%3A+coordination%0Amode%3A+build%0Aneed%3A+4%0Astimulus%3A+Touching+a+hot+pan+%7C+external+%7C+Heat+receptors+in+the+skin+%7C+Spinal+cord+%7C+Arm+muscles+%7C+You+pull+your+hand+away%0Astimulus%3A+Blood+glucose+rises+after+a+meal+%7C+internal+%7C+Glucose+receptors+in+the+pancreas+%7C+Pancreas+%28releases+insulin%29+%7C+Liver+%7C+The+liver+stores+glucose%0Astimulus%3A+A+sudden+fright+%7C+external+%7C+Eyes+and+ears+%7C+Brain%2C+then+adrenal+glands+%28release+adrenaline%29+%7C+Heart+%7C+Your+heart+beats+faster%0Astimulus%3A+Too+little+water+in+the+body+%7C+internal+%7C+Receptors+in+the+brain+%7C+Pituitary+gland+%28releases+ADH%29+%7C+Kidneys+%7C+Less+water+lost+in+urine%0A&fresh=1}}

[Open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/science/biology-9/signals/?full=step-5#step-5)

<!-- Speaker note: What this step is for: A second hormone pathway (ADH and the kidneys) checks that students can apply the model to an unfamiliar case. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## 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

* Answer: The kidneys

<!-- Speaker note: Gland (command centre) → hormone in the blood (messenger) → kidneys (effector) → less water lost (response). -->

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## 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).

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Exit ticket

**Give one difference between how a nerve signal and a hormone travel, and one difference in how long their effects last.**

* Nerve signals are electrical, along nerves; hormones are chemicals in the blood. Nerve effects are brief; hormone effects last longer.

<!-- Speaker note: Students answer on paper or a mini whiteboard before the reveal. Anyone who cannot answer needs the main idea again next lesson. Where this leads: Next: Nerve or hormone? (node 4), then feedback (node 5). In class: reaction-time ruler drop (nerves) beside a discussion of how long a blush or a fright lasts (hormones); a map of the major glands. -->