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LAUNCH · SCIENCE · Lesson 1 of 7

How does a cell receive the right message?

Learning intention

Describe endocrine signalling and explain why suitable internal conditions matter.

A hormone can travel around the body in blood.

Why does every cell not react in the same way?

Success looks like

  • Trace gland → blood → target organ.
  • Explain why a circulating hormone does not affect every cell equally.
  • Explain homeostasis as regulation within suitable limits rather than perfect stillness.
Retrieval

LAUNCH · SCIENCE · Lesson 1 of 7

Transport and conditions

R1. What carries many dissolved substances around the body?

R2. Why do cells need suitable conditions?

R3. Does a chemical messenger think or choose?

I do

LAUNCH · SCIENCE · Lesson 1 of 7

I trace the message route

Gland releases → blood carries → target responds.

The hormone is a chemical messenger.

One message, three important locationsEndocrine transport model: an endocrine gland releases a hormone into circulating blood; the hormone reaches tissues, but only appropriate target cells respond. Arrows show information/material transport, not a private gland-to-organ duct.One message, three important locationsEndocrine glandHormone releasedinto bloodBloodstreamCarrieshormoneTarget cellsRecognise signalChange activityThe bloodstream distributes the signal.Cell recognition helps determine the response.
One message, three important locations
Diagram description

Endocrine transport model: an endocrine gland releases a hormone into circulating blood; the hormone reaches tissues, but only appropriate target cells respond. Arrows show information/material transport, not a private gland-to-organ duct.

I do

LAUNCH · SCIENCE · Lesson 1 of 7

Recognition makes the signal specific

Blood can bring a signal near many cells.

A target cell can recognise it and respond.

A circulating hormone needs a matching responseSimplified receptor model: a purple signal is present near two cells. Cell A has a matching receptor and can respond; cell B lacks that receptor. Shapes model recognition only; real receptors are molecules, not conscious locks.A circulating hormone needs a matching responseCell A: matching receptorA response can occurCell B: no matching receptorNo response to this signalSpecificresponseSame bloodsignal present
A circulating hormone needs a matching response
Diagram description

Simplified receptor model: a purple signal is present near two cells. Cell A has a matching receptor and can respond; cell B lacks that receptor. Shapes model recognition only; real receptors are molecules, not conscious locks.

I do

LAUNCH · SCIENCE · Lesson 1 of 7

Homeostasis keeps conditions suitable

Conditions change; regulation limits departures.

A corrective response reduces the original change.

Some control uses nerves, some uses hormones.

Control reduces a departureGeneral negative-feedback model: a condition departs from a suitable range, the change is detected/coordinated, a response opposes the departure, and the condition moves towards the range. This is a control concept, not a claim that all responses are hormonal.Control reduces a departureCondition departsfrom a suitable rangeChange is detectedand coordinatedCondition movestowards suitable limitsResponse counteractsthe original changeHomeostasis is active regulation, not perfect stillness.
Control reduces a departure
Diagram description

General negative-feedback model: a condition departs from a suitable range, the change is detected/coordinated, a response opposes the departure, and the condition moves towards the range. This is a control concept, not a claim that all responses are hormonal.

We do

LAUNCH · SCIENCE · Lesson 1 of 7

Message-routing desk

Go to interactive investigation

W1. Locate the gland names using the position clues.

Then trace a pancreas hormone from release to response.

Schematic location guide; different reproductive organs are listed, not drawn as one anatomy.
Endocrine structureApproximate position
PituitaryBase of brain
ThyroidNeck
PancreasUpper abdomen
Adrenal glandsAbove the kidneys
OvariesPelvis
TestesScrotum

Message route: predict, test, explain

A qualitative cell-signalling model, not a medical simulation.

Decision 1 of 3

What carries an endocrine hormone to tissues?

Choose, test, then explain together. Evidence diagrams appear only after your test. Diagram transitions explain the model; they do not represent real elapsed time. Use Pause model to stop transitions and model controls, or your device’s reduced-motion setting. The printed We do activity provides the paper route.

We do

LAUNCH · SCIENCE · Lesson 1 of 7

Predict the responding cell

W2. The same hormone reaches cells A and B.

Which cell is more likely to respond in this model?

A circulating hormone needs a matching responseSimplified receptor model: a purple signal is present near two cells. Cell A has a matching receptor and can respond; cell B lacks that receptor. Shapes model recognition only; real receptors are molecules, not conscious locks.A circulating hormone needs a matching responseCell A: matching receptorA response can occurCell B: no matching receptorNo response to this signalSpecificresponseSame bloodsignal present
A circulating hormone needs a matching response
Diagram description

Simplified receptor model: a purple signal is present near two cells. Cell A has a matching receptor and can respond; cell B lacks that receptor. Shapes model recognition only; real receptors are molecules, not conscious locks.

We do

LAUNCH · SCIENCE · Lesson 1 of 7

Control-room repair

W3. “The variable rose, so the controller always pushes it further up.”

Explain what a negative-feedback response should do.

Hinge

LAUNCH · SCIENCE · Lesson 1 of 7

Which explanation links route and recognition?

Choose the mechanism, not a human-like story.

You do

LAUNCH · SCIENCE · Lesson 1 of 7

Build a control explanation

Choose your response page.

Use a route diagram and a cause-and-effect sentence.

You do

LAUNCH · SCIENCE · Lesson 1 of 7

Make the mechanism visible

Source → transport → target → response.

Explain why suitable conditions matter.

Review

LAUNCH · SCIENCE · Lesson 1 of 7

Audience asks about the missing link

L1. Share a short explanation.

Audience: “How did the message reach that cell, and why did it respond?”

Review

LAUNCH · SCIENCE · Lesson 1 of 7

A useful model also has a limit

The model shows a mechanism.

It does not predict exact timings, hormone amounts or clinical outcomes.

Exit

LAUNCH · SCIENCE · Lesson 1 of 7

Three linked ideas

E1. How are endocrine hormones transported?

E2. Why may a non-target cell not respond?

E3. What does homeostasis regulate?

Exit

LAUNCH · SCIENCE · Lesson 1 of 7

Choose the next useful step

Gland location • signal route • target recognition • control.

Continue within this stage’s shared time.

My science task sheets

Choose one route with your teacher. Shared evidence and the exit sheet appear in every route. Your work stays here while the page is open; save it before closing.

Shared evidence | Signals and conditions

Original conceptual cases; no personal health or medical decision is involved.

Endocrine structureApproximate position
PituitaryBase of brain
ThyroidNeck
PancreasUpper abdomen
Adrenal glandsAbove the kidneys
OvariesPelvis
TestesScrotum

Cell model

A hormone is present near both cells A and B. A has a matching receptor; B lacks that receptor.

Control case

An internal variable rises above its usual suitable range. In this model, the control response can reduce that departure.

Conditions case

A cell’s enzyme-controlled reactions depend on suitable temperature. Water balance also affects animal-cell volume.

Supported route | Label the mechanism

Word bank: endocrine gland; blood; target; receptor; response; suitable range.

Standard route | Explain the control room

Use the shared evidence and accurate biological terms.

Stretch route | Test the model

Optional deeper reasoning; detailed Higher-tier hormone cascades are not required.

Exit and reflection | Route, recognition, regulation

Use short explanations or labelled arrows.

Next useful step
Slide 1

TA Brief

Current stage

Objective

Describe endocrine signalling and explain why suitable internal conditions matter.

Preparation

Method precautions

Practical alternative

All evidence is supplied. Use paper diagrams and cards, pointing, annotation or dictation if a device is unavailable.

Access and regulation

Supported: Same core concepts with chunked prompts and read-aloud access. Record support used; a pathway is not a diagnosis or fixed attainment label.

Standard: Explain the supplied evidence independently using accurate scientific terms and units.

Stretch: Optional deeper transfer or evaluation. Higher-tier-only material is labelled explicitly and is not required for the core outcome.

Regulation: Offer solo or partner work, a quiet response, a pass and brief reset with clear re-entry. No forced disclosure or public performance.

Teacher answers

Retrieval and We do

R1: blood; R2: suitable conditions support cell reactions/enzymes and cell integrity; R3: no. W1: use the six locations in the table, then pancreas→blood→responsive tissue. W2: A has matching recognition. W3: the response should reduce the original rise in the model.

Hinge

Correct: circulation plus target recognition. Hormones do not consciously choose. Homeostasis permits change while regulating within suitable limits.

S1 / M1

An endocrine gland releases a hormone into blood. Circulating blood transports it to tissues. Cells with suitable recognition/response machinery respond by changing activity.

S2 / M2

A has the matching receptor; B does not in this model. Both can encounter the hormone. Presence in blood is not the same as an appropriate target response.

S3 / M3

A corrective response opposes the rise and tends towards suitable limits. Homeostasis regulates an internal environment; it does not mean every value is fixed or that all coordination is hormonal.

S4 / M4

Pancreas upper abdomen; thyroid neck. Other valid locations: pituitary base of brain; adrenals above kidneys; ovaries pelvis; testes scrotum. Suitable temperature supports enzyme-controlled reactions; water balance prevents excessive cell swelling/shrinking.

T1

No. Recognition is one requirement; downstream cell machinery must also function. The simple receptor picture omits those steps.

T2

No. Delays and overshoot can occur in regulated systems. A simplified diagram does not show response speeds, competing signals or exact ranges.

T3

Hormones circulate chemically in blood and affect responsive targets. Nerve impulses travel along neurones to connected targets. Typical timing/range differ, but avoid absolute claims that every hormone is slow or every response identical.

T4

The model has no individual measurements, calibrated parameters or clinical context. It illustrates a causal organisation, not a diagnostic instrument.

Exit and assessment

E1: bloodstream. E2: lack of appropriate receptor/response machinery; use the receptor distinction for core. E3: internal conditions within suitable limits so cells function. Secure core: correct route+specificity+dynamic regulation. Re-teach by separately asking “does the signal arrive?” and “can the cell respond?”

Sources checked for this lesson

Word help

hormone
A chemical messenger released by an endocrine gland and carried in blood.
endocrine gland
An organ or tissue that releases hormones into the bloodstream.
target cell
A cell able to respond to a particular hormone, usually because it has the appropriate receptor.
receptor
A molecule that recognises a signal and can trigger a response.
homeostasis
Regulation of internal conditions within suitable limits despite change.
negative feedback
A response that reduces the original departure from a regulated condition.

Cold Call

Give thinking time. Invite a response by voice, pointing or showing work. A pupil can pass; check in privately when useful.

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Take a quiet pause.

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