Human Biology 12 Temperature regulation
Dec 22, 2015
Human Biology 12
Temperature regulation
Metabolism and temperatureMetabolism refers to all reactions occurring in the
bodyMetabolic rate refers to the amount or speed of
reactions in the body. It can be measured by measuring temperature, rate of oxygen consumption or rate of carbon dioxide production
Reactions produce waste heat.The more reactions that occur, the greater the
temperatureReactions rely on enzymes
Enzyme activity and temperature
Enzyme activity
Temperature
Metabolic rate and temperature
As temperature increases, metabolic rate increases
As metabolic rate increases, temperature increases
Heat production
Heat can be produced by:• Metabolism eg respiration
• Movement
Voluntary eg exercise Involuntary eg shivering
Heat loss or gain
Occurs from body surfaces
Uses the processes of:
• Radiation
• Conduction
• Convection
• Evaporation
Radiation
Loss without contact
Most important in terrestrial organisms.
Can be increased by
Increasing surface area exposure eg basking, big ears, vasodilation, bare skin/reduced fur
Can be decreased by
Decreasing surface area exposure eg huddling, small ears, vasoconstriction, fur or feathers
Conduction
Loss by contactMost important in aquatic organismsCan be increased byIncreasing surface area exposure eg larger
extremities, reduced fur, reducing insulation
Can be decreased byDecreasing surface area exposure eg smaller
extremities, increased fur, increased insulation (eg blubber)
Convection
Loss by air movements
Most important in land animals
Can be increased by
Increasing surface area exposure to wind eg sprawling, decreased fur
Can be decreased by
Decreasing surface area exposure to wind eg huddling, fluffing feathers, increased fur
Evaporation
Loss of heat due to liquid turning to gas
Most important in terrestrial organisms
Can be increased by sweating, panting or wetting skin or fur
Can be decreased by reducing sweating or panting, keeping surface dry or covered with thick fur or feathers
Control of body temperature
Control of heat production
Increasing or decreasing metabolic activity or movement (shivering or exercise)
Control of heat loss
Increasing or decreasing loss of heat from external or respiratory surfaces
An example of negative feedback
Stimulus
Negative feedback Receptor
Response Modulator
Effector
Heat
Thermoreceptors
Hypothalamus in brain
Sweat glands
Increased sweating
Cool down
An example of negative feedback
Stimulus
Negative feedback Receptor
Response Modulator
Effector
Thermoreceptors
Hypothalamus in brain
Cold
Muscles
Shivering
Warm up
Structural adaptations
Bare skin or reduced fur
Endomorphic body shape
Counter current exchange
Ectomorphic body shape
Physiological adaptations
Sweating
Increased breathing rateIncreased heart rate
Vasodilation
Vasoconstriction
HunchingShivering
Behavioural adaptations
Use a fan
Immersing in cold water
Seeking shadeResting during heatReduce clothes
Hot bath
Use a heater
Add clothes