Human Thermoregulation Using a negative feedback loop

Homeostasis: maintaining a relatively constant internal environment pH glucose levels salt levels temperature

Control of body temperature Control of body temperature

Control of body temperature Homeostasis: Internal body temperature of approximately 36–38C Control of body temperature

Control of body temperature Homeostasis: Internal body temperature of approximately 36–38C Temperature rises above normal Control of body temperature

Control of body temperature Homeostasis: Internal body temperature of approximately 36–38C Temperature rises above normal Thermostat in brain activates cooling mechanisms Control of body temperature

Control of body temperature Homeostasis: Internal body temperature of approximately 36–38C Temperature rises above normal Thermostat in brain activates cooling mechanisms Sweat glands secrete sweat that evaporates, cooling body Control of body temperature

Control of body temperature Homeostasis: Internal body temperature of approximately 36–38C Temperature rises above normal Thermostat in brain activates cooling mechanisms Sweat glands secrete sweat that evaporates, cooling body Blood vessels in skin dilate and heat escapes Control of body temperature

Homeostasis: Internal body temperature of approximately 36–38C Homeostasis: Internal body temperature of approximately 36–38C Temperature rises above normal Temperature decreases Thermostat in brain activates cooling mechanisms Sweat glands secrete sweat that evaporates, cooling body Blood vessels in skin dilate and heat escapes

Control of body temperature Homeostasis: Internal body temperature of approximately 36–38C Temperature rises above normal Temperature decreases Thermostat in brain activates cooling mechanisms Sweat glands secrete sweat that evaporates, cooling body Blood vessels in skin dilate and heat escapes Thermostat shuts off cooling mechanisms Control of body temperature

Control of body temperature Homeostasis: Internal body temperature of approximately 36–38C Temperature rises above normal Temperature falls below normal Temperature decreases Thermostat in brain activates cooling mechanisms Sweat glands secrete sweat that evaporates, cooling body Blood vessels in skin dilate and heat escapes Thermostat shuts off cooling mechanisms Control of body temperature

Control of body temperature Homeostasis: Internal body temperature of approximately 36–38C Temperature rises above normal Temperature falls below normal Temperature decreases Thermostat in brain activates warming mechanisms Thermostat in brain activates cooling mechanisms Sweat glands secrete sweat that evaporates, cooling body Blood vessels in skin dilate and heat escapes Thermostat shuts off cooling mechanisms Control of body temperature

Homeostasis: Internal body temperature of approximately 36–38C Homeostasis: Internal body temperature of approximately 36–38C Temperature rises above normal Temperature falls below normal Temperature decreases Blood vessels in skin constrict, minimizing heat loss Thermostat in brain activates warming mechanisms Thermostat in brain activates cooling mechanisms Sweat glands secrete sweat that evaporates, cooling body Blood vessels in skin dilate and heat escapes Thermostat shuts off cooling mechanisms

Homeostasis: Internal body temperature of approximately 36–38C Homeostasis: Internal body temperature of approximately 36–38C Temperature rises above normal Temperature falls below normal Temperature decreases Blood vessels in skin constrict, minimizing heat loss Thermostat in brain activates warming mechanisms Skeletal muscles rapidly contract, causing shivering, which generates heat Thermostat in brain activates cooling mechanisms Sweat glands secrete sweat that evaporates, cooling body Blood vessels in skin dilate and heat escapes Thermostat shuts off cooling mechanisms

Control of body temperature Homeostasis: Internal body temperature of approximately 36–38C Temperature rises above normal Temperature falls below normal Temperature decreases Temperature increases Blood vessels in skin constrict, minimizing heat loss Thermostat in brain activates warming mechanisms Skeletal muscles rapidly contract, causing shivering, which generates heat Thermostat in brain activates cooling mechanisms Sweat glands secrete sweat that evaporates, cooling body Blood vessels in skin dilate and heat escapes Thermostat shuts off cooling mechanisms Control of body temperature

Control of body temperature Homeostasis: Internal body temperature of approximately 36–38C Temperature rises above normal Temperature falls below normal Temperature decreases Temperature increases Thermostat shuts off warming mechanisms Blood vessels in skin constrict, minimizing heat loss Thermostat in brain activates warming mechanisms Skeletal muscles rapidly contract, causing shivering, which generates heat Thermostat in brain activates cooling mechanisms Sweat glands secrete sweat that evaporates, cooling body Blood vessels in skin dilate and heat escapes Thermostat shuts off cooling mechanisms Control of body temperature