IB Biology HL 3.3.5 Thermoregulation

Practise analysing thermoregulation data and feedback diagrams, including sweating, diving responses and heat-transfer calculations.

Exam points

Analyse feedback diagrams to identify coordinated thermoregulation responses.
Interpret temperature data and calculate differences in heat-transfer investigations.
Explain sweating and peripheral responses as mechanisms for maintaining core temperature.

[Maximum number: 8]

Explain the control of body temperature in humans.

normal body core temperature constant/ 36.5 to $37.5^{\circ} \mathrm{C}$ ; $\quad \begin{aligned} & \text { (accept single values } \\ & \text { within this range) }\end{aligned}$ within this range)
regulated by negative feedback/homeostatic mechanisms; hypothalamus is the centre of thermoregulation; hypothalamus sends impulses to the body to increase/decrease temperatures; release of sweat (by sweat glands in the skin) if skin temperature rises; evaporation of water cools the body; (concept of evaporation must be mentioned) heat is transferred by blood; transfer of heat from body core in blood to surface;
if temperature rises, increased flow of blood/heat to the skin/vasodilation of skin blood vessels/arterioles;
(do not accept veins, arteries or capillaries) (do not accept veins, arteries or capillaries)
if temperature drops, decreased flow of blood/heat to the skin/vasoconstriction of skin blood vessels/arterioles;
(eg reducing activity (to lower body temperature) / reducing exposed surfaces (to reduce heat loss)
[8 max]

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D3.3.5—Thermoregulation question 1