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IGCSE · Cambridge (CIE) · 0654

Explain the brain coordinating temperature responses

Link detected temperature departures to the appropriate effectors.

Homeostasis · Cambridge IGCSE 0654 · B13.3

Mapped to the named 0654 section using teaching from the corresponding single-science course. A 0654-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade.

Before you begin

  • Recall hormone production and blood transport, respiration, liver storage and electrical impulses along neurones.

Work on paper. Try each question before revealing help, and explain why your method works.

Quick readiness check

Which organ coordinates the required response?

What you will learn

  • Describe temperature detection and coordination
  • Choose warm and cold corrective responses

Explain the brain coordinating temperature responses

Brain coordinates temperature responses: sweating and heat-loss responses after a rise; shivering and reduced-loss responses after a fall. Return reduces the stimulus.Temperature departureBrain coordinates effectorsHeat production or loss changesReturn reduces stimulusResponses oppose the departure
Brain coordinates temperature responses: sweating and heat-loss responses after a rise; shivering and reduced-loss responses after a fall. Return reduces the stimulus. Original teaching model.
Homeostasis model reference
FeatureMeaning
CoordinatorBrain; hypothalamus region
Above referenceCooling effectors increase
Below referenceHeat production and conservation responses
FeedbackReturn reduces corrective responses

Describe temperature detection and coordination

The brain coordinates mammalian temperature regulation. A coordinating region, the hypothalamus, monitors internal temperature and receives information about temperature conditions from receptors. Signals from the coordinating system change effector activity. Receptors in the skin can supply information, but the pictured touch receptor in the identification sources is not specifically labelled as a thermoreceptor.

When internal temperature is above its regulated level, the brain coordinates responses such as increased sweating and increased skin surface blood flow. In surroundings cooler than the body, these can increase heat loss. Shivering is reduced rather than selected as the main cooling response, because its muscle activity would generate additional heat.

Choose warm and cold corrective responses

When internal temperature is below its regulated level, the brain coordinates shivering and reduced surface blood flow, with insulating responses relevant to the mammal’s coat. Shivering increases heat production, while the other responses reduce heat loss. The brain is the coordinator rather than the organ that physically secretes sweat or supplies the entire insulating fat layer.

The response directions depend on the departure from the regulated level. As that departure becomes smaller, the corrective responses are reduced through negative feedback. A simplified model may use a supplied reference near 37°C, but this is not an exact universal reading for every person at every time. Use the stated reference in a question and keep the mechanism distinct from clinical assessment.

Sources for this lesson

Pause and explain

Which response set is appropriate after internal temperature falls?

Put the idea to work

Worked example

Explain the role of the brain after internal temperature rises.

Show the worked solution
  1. The coordinating brain region detects/receives temperature information.
  2. It coordinates cooling effectors and reduces the response as temperature returns.

Answer The brain coordinates increased sweating and appropriate increased surface blood flow after a rise; return towards the regulated level reduces the corrective response.

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From guided practice to a new situation

Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.

1 · Guided

State the brain’s role in temperature regulation.

Give me a hint

Separate detection/coordination from physical effectors.

Compare my reasoning
  1. The brain monitors/receives temperature information.
  2. It coordinates effector responses that oppose the departure.

The brain monitors and receives temperature information and coordinates appropriate effector responses to restore temperature towards its regulated level.

Look for these in your work

  • Include temperature information
  • Include corrective coordination
2 · Independent

Choose and explain one response for high and one for low internal temperature.

Give me a hint

Use opposite correction directions.

Compare my reasoning
  1. High: sweat evaporation removes heat.
  2. Low: shivering muscle respiration produces more heat.

High temperature: increased sweat evaporation removes heat. Low temperature: shivering increases respiration and heat production.

Look for these in your work

  • Explain the high response
  • Explain the low response
3 · Transfer

Why cannot the source Merkel cell automatically be labelled the thermoreceptor for this brain-control diagram?

Give me a hint

Distinguish a generic identification requirement from specific receptor function.

Compare my reasoning
  1. The source labels a touch-associated receptor.
  2. It does not identify a specific temperature detector.

The source supports touch-receptor identification, not a particular thermoreceptor label. The temperature-control model must state its own receptor scope.

Look for these in your work

  • Use source-specific evidence
  • Avoid unsupported stimulus specificity

Common mistakes

  • Saying the brain itself secretes skin sweat.
  • Choosing shivering as the main cooling response.
Recall without your notes

What can you explain now?

Which response set is appropriate after internal temperature falls?

Compare with the explanation

Shivering and reduced surface blood flow

These increase production and reduce loss respectively.

After trying it yourself, choose your next review. This is your self-assessment.

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Make it stick

Describe the brain’s role and choose effectors that oppose the stated departure.

If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.

Keep learning Sciences — Co-ordinated (Double)

Course scope and assessment

This 2028–2029 pathway maps all 152 detailed subject-content sections in the published 0654 syllabus to original teaching and staged practice. It adapts teaching from the related single-science pathways and excludes clear 0610-only topics such as classification systems, human excretion, tropic responses, food supply, population dynamics, detailed pollution and biotechnology. Some explanations may include wider single-science context. A 0654-specific objective-by-objective review, Core/Supplement audit, human subject-teacher review, supervised laboratory experience and cumulative assessment remain in progress. Written practice is self-checked and does not predict an official grade. The 2025–2027 syllabus has not been reconciled here; choose the 2028–2029 syllabus only.

StudyForA · Learn with understanding

Original teaching content and links to official sources. Check your exam year and qualification before using a resource.