biology 12. metabolism and temperature metabolism refers to all reactions occurring in the body...
Post on 17-Dec-2015
221 Views
Preview:
TRANSCRIPT
Biology 12
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
Size and metabolic rateSmaller animals have a larger surface area
to volume ratio than larger animals
Animals lose heat from body surfaces, so smaller animals will lose more heat than larger ones
Metabolic rate is usually higher in smaller animals
Body temperaturePoikilotherms have changing body
temperatures - the same as their environment
eg fish, amphibians, reptilesHomeotherms have constant body
temperatures regardless of the environment
eg birds, mammalsEctotherms control body temperature
by behavioureg fish, amphibians, reptilesEndotherms control body temperature
by internal mechanisms eg birds, mammals
Environmental temperature
Bodytemperature
Metabolic rate
Environmental temperature
Poikilotherms
Endotherms
Homeotherms
Ectotherms
Endothermy vs Ectothermy
Endothermy Ectothermy
Advantages Can survive in a wide range of conditions and habitats eg Antarctica, winter
Don’t need a constant food supply to drive metabolism
Have simple control mechanisms
Disadvantages Must have a constant food supply to drive metabolism
Have complex control mechanisms
Can not survive in as wide a range of conditions and habitats eg Antarctica, winter
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 orreduced fur
Large ears/extremities Small ears/extremities
Small body size
Large body size
Dark extremities
Fur orfeathers
blubber
Counter current exchange
Physiological adaptationsSweating
Aestivation
Panting
Vasodilation Vasoconstriction
Hibernation
Fluffing feather or fur
Behavioural adaptationsLicking fur
Seeking shadeResting during heat
Dipping feet in water
Burrowing
Nocturnal
Basking
Migration
Huddling
Clothes
top related