5.2.4: Control of body temperature (biology only)
Not started yet — this one needs some love.
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.
Temperature receptors in the skin send nervous impulses to the thermoregulatory centre.
If body temperature is too high, blood vessels dilate by vasodilation and sweat is produced by sweat glands.
Vasodilation and sweating increase the transfer of energy from the skin to the environment.
If body temperature is too low, blood vessels constrict by vasoconstriction, sweating stops and skeletal muscles contract to shiver.
Shivering helps raise body temperature because muscle contraction increases respiration and energy transfer.
Common exam mistakes
Do not say blood vessels move closer to the skin surface; vasodilation means they widen.
Sweating cools the body when sweat evaporates, not simply because sweat is produced.
Vasoconstriction reduces energy transfer from the skin; do not describe it as increasing heat loss.
In context questions, match the response to the temperature problem: vasodilation and sweating for too hot, vasoconstriction and shivering for too cold.