Ectotherms Regulation of body temperature in Body temp fluctuates with the environment Controlled by; exposure to the sun shelter heat from the ground metabolic heat from respiration colour variations (to alter heat radiation) Endotherms Regulation of body temperature in Most heat gained through internal metabolic activities CONSERVING HEAT IN COLD ENVIRONMENTS Small surface area to volume ratio = relatively large Smaller extremities fur/feathers/fat thick Vasoconstriction reducing the diameter of arterioles near skin’s surface so stays – below the layer of fat Shivering in voluntary rapid movements that produce metabolic heat energy from – respiration Raising hair enables a thick layer of still air to build up which acts as a good insulator. – Increased metabolic rate more hormones that increase metabolic rate are produced so – higher metabolic and respiration rate Behavioural mechanisms bathing in the sun – Decreased sweating LOSING HEAT IN WARM ENVIRONMENTS = smaller animals Large surface area to volume ratio Larger extremities Light coloured fur to reflect heat Vasodilation Arterioles increase in diameter so warm passes close to skin’s surface – and radiates heat Lower body hair Hair erector muscles relax. Hairs flatten, reduces the insulating layer of air – Behavioural mechanisms seeking shade, burrows, etc – Increased sweating Heat energy is required to evaporate sweat. The energy comes from – the body. Therefore, removes heat energy to evaporate water Control of body temperature The hypothalamus measures the INTERNAL temperature of blood passing through it Thermoreceptors in the skin measure the EXTERNAL temperature
Regulation of body temperature in Ectotherms Body temp fluctuates with the environment Controlled by; exposure to the sun shelter heat from the ground metabolic heat from respiration colour variations (to alter heat radiation) Regulation of body temperature in Endotherms Most heat gained through internal metabolic activities CONSERVING HEAT IN COLD ENVIRONMENTS Small surface area to volume ratio = relatively large Smaller extremities thick fur/feathers/fat Vasoconstriction – reducing the diameter of arterioles near skin’s surface so stays below the layer of fat Shivering – in voluntary rapid movements that produce metabolic heat energy from respiration Raising hair – enables a thick layer of still air to build up which acts as a good insulator. Increased metabolic rate – more hormones that increase metabolic rate are produced so higher metabolic and respiration rate Behavioural mechanisms – bathing in the sun Decreased sweating LOSING HEAT IN WARM ENVIRONMENTS Large surface area to volume ratio = smaller animals Larger extremities Light coloured fur to reflect heat Vasodilation – Arterioles increase in diameter so warm passes close to skin’s surface and radiates heat Lower body hair – Hair erector muscles relax. Hairs flatten, reduces the insulating layer of air Behavioural mechanisms – seeking shade, burrows, etc Increased sweating – Heat energy is required to evaporate sweat. The energy comes from the body. Therefore, removes heat energy to evaporate water Control of body temperature The hypothalamus measures the INTERNAL temperature of blood passing through it Thermoreceptors in the skin measure the EXTERNAL temperature