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# Nerve or hormone?

Year 9 Biology · Coordination and control

<!-- Speaker note: Students compare the nervous and endocrine systems by message, route, speed, duration and target (AC9S9U01, node 4, a hinge node). About 20 minutes (Engage and Explore 6 min · Explain 9 min · Evaluate 3 min · Typical adds 2 min, Wider about 2 min). -->

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## Today

**We are learning to** the nervous system sends fast, short-lived electrical impulses along nerves to one place. The endocrine system releases hormones into the blood: slower, longer-lasting, and they reach every cell but act only on target cells.

- I can explain that hormones travel in the blood, not along nerves.
- I can compare nervous and hormonal responses by speed and duration.
- I can explain why only target cells respond to a hormone.

<!-- Speaker note: Before class: A concept tutorial for introducing or revising the idea. Set the width with `?width=minimum`, `typical` (default) or `wider`. The hinge misconception is that hormones travel along nerves. The Engage question puts it directly. Board notes: the race is schematic, compressing about 10 minutes into 5 seconds; the curves show shape (sharp spike against slow rise and long tail), not real values. -->

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## Why it matters

> A fright makes you jump in a fraction of a second. Your heart is still pounding a few minutes later. Two different systems are at work.

<!-- Speaker note: The nervous system is one way the body sends messages. This lesson: the other way, and how they compare. -->

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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

**Adrenaline is a hormone released when you get a fright. How does it reach your heart?**

- It is made in the heart
- In the blood, carried all round the body
- Through the air you breathe
- Along a nerve, like an impulse

<!-- Speaker note: What happens: In the blood. The adrenal glands release it into the bloodstream, which carries it everywhere; cells with the right receptors (heart, liver, muscles) respond. Take two or three predictions before anyone runs it. -->

<!-- Speaker note: Teacher: count how many chose 'along a nerve'. -->

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## Explore it

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

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

<!-- Speaker note: Press **Race** and watch both responses to the same fright. Which starts sooner? Which lasts longer? -->

<!-- Speaker note: Teacher: ask what the long tail of the hormone curve feels like after a fright. -->

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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. The adrenal glands release it into the bloodstream, which carries it everywhere; cells with the right receptors (heart, liver, muscles) 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>

## Which system

**Nervous system or endocrine system?**

Groups: Nervous system · Endocrine system

Electrical impulses · Chemical messages in the blood · Very fast · Effects last minutes to years · Goes to one exact place · Reaches the whole body; target cells respond

* Answer: Electrical impulses → Nervous system; Chemical messages in the blood → Endocrine system; Very fast → Nervous system; Effects last minutes to years → Endocrine system; Goes to one exact place → Nervous system; Reaches the whole body; target cells respond → Endocrine system

<!-- Speaker note:  -->

<!-- Speaker note: Teacher: the target-cell question is the checkpoint. -->

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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>

## Target cells

**Every cell in the body gets the same adrenaline in the blood. Why do only some cells respond?**

- Other cells destroy it
- The brain tells the other cells to ignore it
- Adrenaline only flows to the heart
- Only target cells have receptors that fit adrenaline

* Answer: Only target cells have receptors that fit adrenaline

<!-- Speaker note:  -->

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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>

## The right tool

**Growth over years is controlled by growth hormone, not nerves. Why is a hormone better for this job?**

- The effect needs to last a long time and reach cells all over the body
- Hormones are faster
- Growth is a reflex
- Nerves can't reach bones

* Answer: The effect needs to last a long time and reach cells all over the body

<!-- Speaker note:  -->

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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>

## Which one?

**A sprinter reacts to the starting gun. Which system carries the message to the leg muscles, and why?**

- Endocrine: a hormone in the blood reaches every leg muscle at once
- Both equally: every response uses both systems
- Endocrine: the race lasts a long time, so the effect must last
- Nervous: the response must be very fast and go to particular muscles

* Answer: Nervous: the response must be very fast and go to particular muscles

<!-- Speaker note:  -->

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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>

## Elaborate: both at once

**A car swerves towards you on your bike. Which part of your response is nervous and which is hormonal?**

Groups: Nervous · Hormonal

You brake and steer away · Your heart is still racing five minutes later · Your hands are shaky as you ride home · You flinch

* Answer: You brake and steer away → Nervous; Your heart is still racing five minutes later → Hormonal; Your hands are shaky as you ride home → Hormonal; You flinch → Nervous

<!-- Speaker note: What this step is for: A real response often uses both systems, each for what it does best. -->

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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>

## Elaborate: insulin

**After a meal, the pancreas releases insulin. Liver and muscle cells take up glucose from the blood. Which describes it?**

- The pancreas is the gland, insulin is the hormone, liver and muscle cells are targets
- Glucose is the hormone
- The liver is the gland, insulin is the target
- Insulin is a nerve impulse from the pancreas

* Answer: The pancreas is the gland, insulin is the hormone, liver and muscle cells are targets

<!-- Speaker note: What this step is for: A hormone with a clear target links this lesson to blood sugar control in the next. -->

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## Evaluate: look back

Write one sentence: "At first I thought… Now I think… because…"

**Revision summary**

- **Nervous system:** electrical impulses along neurons; very fast; short-lived; to one exact place.
- **Endocrine system:** **hormones** released by **glands** into the **blood**; slower; longer-lasting; reach every cell but act only on **target cells** with matching receptors.
- Many responses use both.

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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 two differences between a nervous and a hormonal response.**

* Nerves: electrical, fast, short-lived, one place. Hormones: chemical in the blood, slower, longer-lasting, target cells everywhere.

<!-- 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: negative feedback (node 5), using both systems to control body temperature. -->