Body temperature

  • Created by: ppogba
  • Created on: 16-08-19 15:53
What happens to the body if temperature is too low?
slow metabolism, inadequate oxygen supply, freezing of cells.
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What happens if temperature is too high?
proteins denature, inadequate oxygen supply, membrane structure alterations
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Name 4 heat exchange processes?
Radiation, conduction, convection, evaporation.
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What is radiation and how much heat is lost from it?
without contact. 60% heat loss.
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What is conduction and how much heat is lost from it?
with contact. 3% heat loss.
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What is convection and how much heat is lost from it?
air/fluid across body surfaces. 15% heat loss.
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What is evaporation and how much heat is lost from it?
water from body surface. 22% heat loss.
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What else could we lose heat from?
respiration
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How do we moderate heat exchange processes?
Large animals have smaller SA:vol ratio, so lose heat less quickly. Temperature gradient-lower gradient between body and environment means slower heat transfer. Specific heat conductance- insulation reduces heat lost.
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What kind of animals are Ectotherms?
lizards, turtles, frogs
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What else are ectotherms known as?
Poikilotherms
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Ectotherms body temperature fluctuates with the environment, as they gain their heat from the environment. What are they known as due to this?
conformers
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How do endotherms differ from ectotherms regarding body temperature? What are they also known as due to this?
endotherms have a constant body temperature, as their heat is derived from their metabolism. They are therefore known as regulators.
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What other name is given to endotherms?
homeotherms.
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There are exceptions to how endotherms regulate their heat. What are they?
they may regulate their body temp. by behaviour- sit in shade or cool off in sea.
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Similarly, ectotherms have exceptions. What are they?
they may use metabolic heat to warm up- insects shiver to warm up flight muscles.
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What are the benefits of ectothermy?
Metabolic rate 5x slower than for endotherms- require less food. Less energy=less food=less water. can devote lots of energy to reproduction. good colonisers of poor/arid environment.
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What are the costs of ectothermy?
they can't be nocturnal (unless in tropical climates as its still hot at night). Cannot sustain high activity bursts as risk O2 debt. Anaerobic=lactate accumulation=rapid fatigue. ambush predators, but susceptible to predation from endotherms.
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What are the benefits of endothermy?
can sustain high activity bursts. can be nocturnal in all habitats. able to exploit colder environments. forage widely and migrate long distances.
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What are the costs of endothermy?
they require large body sizes with low SA:vol ratios. metabolic rate 5x faster than for ectotherms. require more energy=more food=more water. can't devote large amounts of energy budget to reproduction. poor colonisers of poor/arid environment.
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What is the Thermoneutral zone?
range of temperatures in which animal does not expend energy to maintain Tb (body temperature).
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What are the 2 boundaries above and below the thermoneutral zone called?
Upper critical limit and Lower critical limit.
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What does the body have to do if temperatures go above/below these boundaries?
the body must expend energy to maintain Tb.
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These boundaries are set by a control centre. What is the control centre for temperature?
set by the Hypothalamus.
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If the body gets too hot or cold, the hypothalamus will set in motion thermoregulators that will bring the body back to normal. What is this an example of?
negative feedback.
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When our bodies get too cold, what happens to our blood vessels?
Vasoconstriction
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What is vasoconstriction and what is the result of it?
diameter of blood vessels decreases- blood flow to skin decreases, skin cools. Less heat lost to environment through radiation, conduction, convection. Heat trapped in body core.
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If heat loss continues to occur, what does the body do?
shivering
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Describe shivering?
rapid contractions of skeletal muscles. does consume ATP, but increases heat production by 500%
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When primary fuel- glycogen- runs out, what does the body use as fuel instead?
proteins and lipids.
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Hormones are also used to increase heat, one being Adrenaline. Where is it released from and what does it do to increase heat?
released from adrenal medulla. stimulates fight or flight- increases heart rate.
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Name another hormone that increases heat. Where is it released from and what does it do?
Thyroxine- released from thyroid. increases basal metabolic rate.
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For insulation, we have Brown Adipose Tissue (Brown fat). What makes it so effective at reducing heat loss?
rich in mitochondria that ONLY breaks down fuel into heat (usually broken down into energy and heat). rich in blood supply and specialised for rapid heat production.
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Where is Brown Adipose Tissue found?
newborn mammals, hibernating mammals, necks and between shoulder blades of human adults?
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What is the other type of insulator tissue found in the body?
White Adipose tissue- no intracellular organelles, little blood supply.
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What is meant by Countercurrent heat exchangers?
warm arterial blood flows by cooler venous blood (veins) and exchanges heat, so cold blood doesn't return to heart.
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Give examples of where countercurrent heat exchangers occur in the animal kingdom
Legs of a stork standing in cold water, a dolphins fin, whales tongue, turtle flippers.
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Brown fat is good for heat loss, but what other things do animals use for insulation?
Blubber- thick layer of vascularised adipose tissue under skin of sea mammals. Fur/hair/feathers- reduces convection, but effect lost if air is replaced by water.
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What helps the polar bear reduce heat loss?
compact ears, small tail, large body.
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What occurs to our blood vessels if we go above the UCL (get too hot).
Vasodilation
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How does vasodilation cool our bodies down?
diameter of blood vessels increases, blood flow to skin increases, skin heats up, more heat lost to E through radiation, conduction and convection.
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What else does our bodies do to cool down?
Perspiration- glands in skin secrete heat onto surface to increase heat loss by evaporation- evaporative cooling. Sweat also increases convection rate.
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Some mammals cannot sweat to cool down. What do they do?
Panting- evaporation of moisture from mouth and tongue. Exchange hot air in lungs with cooler external air.
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Birds don't have sweat glands. What 2 things to they do to cool down?
Gular flutter- rapidly flap membrane in the throat to increase evaporation. Urohidrosis- **** on legs for evaporative cooling.
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If you can't get your temperature back into the thermoneutral zone, what happens when you become too cold and too hot?
Hypothermia- too cold. Hyperthermia- too hot.
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What are the symptoms of hypothermia and hyperthermia.
Hypothermia- extreme shivering, body temp. falls, oxygen saturation goes down, confusion, headache. Hyperthermia- vomit, heatstroke, headache, fainting, confusion.
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Summary: What do thermo receptors in hypothalamus and in skin detect?
thermo receptors in hypothalamus detect blood temperature. thermo regulators in skin detect external temperature.
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Other cards in this set

Card 2

Front

What happens if temperature is too high?

Back

proteins denature, inadequate oxygen supply, membrane structure alterations

Card 3

Front

Name 4 heat exchange processes?

Back

Preview of the front of card 3

Card 4

Front

What is radiation and how much heat is lost from it?

Back

Preview of the front of card 4

Card 5

Front

What is conduction and how much heat is lost from it?

Back

Preview of the front of card 5
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