Control of Body Temperature (AQA GCSE Biology): Revision Note
Exam code: 8461
Monitoring of body temperature
The human body needs to maintain a temperature at which enzymes work best, around 37°C
Processes such as respiration release energy as heat; and the body loses heat energy to its surroundings – the energy gained and lost must be regulated to maintain a constant core body temperature
Body temperature is monitored and controlled by the thermoregulatory centre in the brain
The thermoregulatory centre contains receptors sensitive to the temperature of the blood
The skin contains temperature receptors and sends nervous impulses to the thermoregulatory centre
Diagram of cross-section of human skin
Controlling body temperature
High body temperature
If body temperature is too high:
blood vessels dilate (vasodilation)
sweat is produced from the sweat glands
Both these mechanisms cause a transfer of energy from the skin to the environment, cooling the body down
Low body temperature
If body temperature is too low:
blood vessels constrict (vasoconstriction)
sweating stops
skeletal muscles contract (shivering)
These skin mechanisms reduce heat loss to the surroundings, while skeletal muscle contraction increasing the heat energy released inside the body
Examiner Tips and Tricks
Remember that during temperature regulation the blood vessels do not move, they dilate (widen) or constrict (narrow) to regulate blood flow to the skin surface.
Explaining body temperature control
Higher Tier Only
The mechanisms that regulate body temperature can be explained as follows:
Body temperature | Mechanism | Explanation |
|---|---|---|
High | Sweat is secreted onto the skin surface by sweat glands | Evaporation requires energy; this energy is transferred from the skin to the sweat, cooling the skin |
Blood vessels supplying the skin get wider (vasodilation) | This increases blood flow near the skin surface, increasing the rate at which energy is transferred from the blood to the environment by radiation | |
Low | Skeletal muscles contract and relax rapidly, causing shivering | Skeletal muscle contraction requires energy from respiration, which releases heat energy |
Blood vessels supplying the skin get narrower (vasoconstriction) | This decreases blood flow near the skin surface, reducing the rate at which energy is transferred from the blood to the environment |
Examiner Tips and Tricks
You need to understand temperature regulation well enough to be able to explain how it functions in a context provided by an exam question, e.g.:
how drinking cold water might cause brain temperature to decrease
think about how the water cools blood vessels near the mouth/throat before it reaches the brain
how temperature might be regulated in a hibernating mammal
think about how metabolic rate, and therefore heat production from respiration, are likely to change during hibernation
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