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D3.3.5—Thermoregulation

Thermoregulation maintains core body temperature by detecting changes and activating heat loss or heat conservation responses in human physiology in human physiology.

Syllabus
First assessment 2025
Objective
D3.3.5
Level
HL

Exam analysis

Chance of appearing4%of analysed past papers
Latest appearanceMay 2023
Most common paperPaper2
Typical marks1–8

Common command terms

  • Describe
  • Explain
  • Identify
  • Outline

Recent exam appearances

May 2023Paper2 ["HL"] · TZ14(b)(ii)[ 2 ]D3.3.5—Thermoregulation
May 2022Paper2 ["HL"] · TZ11(a)[ 1 ]D3.3.5—Thermoregulation
May 2014Paper2 ["HL"] · TZ21(f)[ 2 ]D3.3.5—Thermoregulation
May 2013Paper2 ["HL"] · TZ26(c)[ 8 ]D3.3.5—Thermoregulation
Practice this objective

Coverage 2013–2023 · Updated 16 Jul 2026

Thermoregulation Is a Negative-Feedback Control System

Human thermoregulation detects deviation in core temperature and coordinates effectors that reverse the change.

Control component Role
Peripheral thermoreceptors Detect temperature changes, especially at the skin
Hypothalamus Integrates peripheral and central temperature information
Pituitary/thyroid pathway Alters thyroxin signalling and therefore metabolic heat production
Skeletal muscle Shivering raises respiration and heat production
Brown adipose tissue Uncoupled respiration releases energy as heat

A fall in temperature is detected, the hypothalamus coordinates reduced heat loss and increased muscle/adipose heat production, and the response decreases as core temperature recovers.

The regulated variable is core temperature; skin temperature can change more rapidly and acts partly as an early environmental signal.

Thermoregulation exam focus

Assessment in practice

1–8 marks
How it is assessed

This objective is assessed through structured response, commonly using Describe / Explain / Identify.

Command terms

Describe / Explain / Identify / Outline

What earns marks

Build the answer around this relationship: The hypothalamus coordinates body temperature control.

Representative question

Question 1

[Maximum number: 8]

Explain the control of body temperature in humans.

Retrieve the Core Homeostasis Route

Core D3.3 is secure when every example becomes a feedback route: identify the variable, detect deviation, coordinate a response, activate effectors, and reverse the change. Glucose and temperature are the key worked examples.

  • stable internal environment within narrow limits
  • detects deviation from set point and reverses it
  • insulin lowers high glucose; glucagon raises low glucose
  • hypothalamus coordinates cooling or warming responses

Core Homeostasis

Core homeostasis answers should use a control-loop structure, not a list of responses. The response starts with the variable and set point, then explains how the body detects deviation and activates the response that reverses it. Apply that loop to glucose, diabetes, or temperature.

  • Define homeostasis as maintaining stable internal conditions within narrow limits.
  • Use negative feedback language: receptor, coordinator, effector, set point, and reverse the deviation.
  • Apply the loop to insulin/glucagon, diabetes types, or hot/cold thermoregulation responses.

Concept essentials

  • The hypothalamus coordinates body temperature control.
  • Sweating and vasodilation increase heat loss when body temperature is high.
  • Shivering and vasoconstriction help conserve or generate heat when body temperature is low.