BRAINCAKEKeeping Cool
When core temperature rises above the norm, for example during exercise or on a hot day, the hypothalamus triggers responses that increase heat loss and reduce heat production.
Sweating. Sweat glands secrete more sweat onto the skin. Water in sweat needs energy to evaporate (its latent heat of vaporisation). This energy is taken from the skin as heat, so the skin and the blood flowing through it are cooled. When the surroundings are hotter than the body, radiation, conduction and convection transfer heat into the body, so evaporation becomes the only way to lose heat. Sweating cools less well in humid air, because less water can evaporate. Some mammals, such as dogs, have few sweat glands and pant instead, losing heat by evaporation from the mouth, tongue and airways.
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Key terms in this lesson
- vasodilation
- Widening of a blood vessel, which increases blood flow through it.
- latent heat
- The energy needed to change the state of a substance, such as evaporating water in sweat, without changing its temperature.
More in Homeostasis
- Endotherms
- Ectotherms
- Thermoregulation in Endotherms
- The Skin
- Keeping Warm
- Control of Core Body Temperature
- Vasodilation
- Vasoconstriction
All 41 lessons in Homeostasis · All Edexcel A-level Biology topics