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TEMPERATURE. 350 o C (662 F) -89 o C -128 F 0 o C (32 F) Large Polar Mammals -60 o C Few Species of Fish 44 o C Deep sea Hydrothermal vents Antarctica.

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Presentation on theme: "TEMPERATURE. 350 o C (662 F) -89 o C -128 F 0 o C (32 F) Large Polar Mammals -60 o C Few Species of Fish 44 o C Deep sea Hydrothermal vents Antarctica."— Presentation transcript:

1 TEMPERATURE

2 350 o C (662 F) -89 o C -128 F 0 o C (32 F) Large Polar Mammals -60 o C Few Species of Fish 44 o C Deep sea Hydrothermal vents Antarctica Prokaryotes (bacteria, cyanobacteria) span almost the entire range of Earth’s Temperatures. Vertebrates can tolerate only a small portion of this range.

3 Environment Physiology Morphology Behavior Temperature sets limits… performanceDarwinian fitness

4 Limits at the Cellular Level Increased Temperature speeds up biochemical reactions… …to a point Rate of reaction Increasing T Biochemical structures (i.e. enzymes) breakdown

5 … but limits are species-specific Temperature Performance Thermal performance curves: generalist specialist Lower lethal temp Upper lethal temp

6 Temperature Outline Definitions: –Heat Transfer Example: Camels are cool! –Physiological strategy: endo, ecto, etc. –Temperature tolerance Extreme Temperature: HEAT –Death? –Avoidance strategies –Tolerance strategies Extreme Temperature: COLD –Death? –Avoidance strategies –Tolerance strategies

7 Temperature Basics Heat Transfer Thermal Strategies Thermal Tolerance

8 Heat transfer between animals and environment

9 What’s the difference between temperature & heat? 1 Calorie = energy required to raise 1g of water 1 o C How many calories to heat 1g water from 25 o C to 50 o C? = 25 calories How many calories to heat 100g water from 25 o C to 50 o C? = 2500 calories Measure of intensity of heat ( o C, o F, K) Total KE (calories or joules) Same temp, Different heat content

10 Body temperature depends on heat stored Heat production (metabolism) - Heat out + Heat in = Heat stored Gains > losses

11 “The Rules” 1.Heat flows from warmer cooler 2.Greater temperature gradient, greater flux 3.Physical properties matter 4 Mechanisms of heat transfer Conduction Conduction + Convection Radiation Evaporation

12 1. Conduction = heat transfer between bodies in direct physical contact temperature differential area of contact conductivity of materials

13 2. Convection - Accelerates heat transfer between a solid and a fluid = bulk movement of fluid Why? Hot object CONDUCTION ONLY Hot object CONDUCTION AND CONVECTION Boundary Layer is Removed

14 2. Convection …All fluids come to rest at a solid surface Size of boundary layer is influenced by: size (and shape) of animal Thicker boundary layer, less heat loss to conduction Fluid speed Distance from solid surface 0 fluid speed (air, H 2 O) surface roughness Air reaches full speed = “boundary layer”

15 3. Radiation = transfer of heat between objects without contact Short wavelengths Long wavelengths Above absolute zero, all objects emit & receive radiation ∞ -intensity T4T4 -hotter surface, shorter wavelengths Area of radiative surface is, too Surface temperature is important:

16 4. 35 o C, it takes 580 cal to vaporize 1g of H 2 O! exposure of moist surfaces moisture gradient =Extremely effective method of losing heat

17 4. Evaporation exposure of moist surfaces moisture gradient =Extremely effective method of losing 35 o C, it takes 580 cal to vaporize 1g of H 2 O!

18 Infrared thermal radiation from lizard Infrared thermal radiation from rock Direct sunlight Conduction from rock + Convection by wind Evaporation Infrared thermal radiation from atmosphere Heat flux from different sources is additive Conduction to air Heat Production (metabolism) + HEAT IN HEAT OUT - = Body Temp

19 Temperature Basics Heat Transfer –Conduction –Convection –Radiation –Evaporation Example: CAMELS ARE COOL!!! Thermal Strategies Thermal Tolerance

20 CAMELS BODY HEAT REGULATION WATER BRAIN FUNCTION T a (air temp) can exceed 50ºC (138 F) Normal mammalian body temp = 37ºC How do they cope????

21 How do camels manage to live in the desert heat? 1. Thick fur: prevents heat gain

22 How do camels manage to live in the desert heat? 1.Thick fur: prevents heat gain 2. Body Heat can increase above 37 º C  Body temp can increase to 41ºC (106ºF)  Heat can be lost at night, don’t need to lose water through evaporative cooling  Saves 5 L of water a day  Lowers temp difference between air and camel

23 How do camels manage to live in the desert heat? 1.Thick fur: prevents heat gain 2. Body Heat can increase above 37 º C 3. Fat stored in Hump, not under skin Why Helpful??? During cool nights, heat loss is not restricted

24 CAMELS BODY HEAT REGULATION –Thick Fur –Body Heat to 41 ºC –Fat stored in hump WATER BRAIN FUNCTION T a (air temp) can exceed 50ºC (138 F) Normal mammalian body temp = 37ºC How do they cope????

25 How do camels manage to live in the desert heat? 1.Can go for 3-4 days without water When they reach water, they can drink up to 100L in 10 minutes

26 How do camels manage to live in the desert heat? 1.Can go for 3-4 days without water 2. Minimize water loss …  Concentrate Urine  Camel does not sweat (until body temp above 41)  The NOSE:  Main place for evaporative cooling  Our nasal passages 10 cm 2  Camel Nasal Passages 1000 cm 2  Called ‘nasal turbinate’  Can open and close to save water  Nasal Membranes are HYGROSCOPIC (very cool)

27 CAMELS BODY HEAT REGULATION –Thick Fur –Body Heat to 41 ºC –Fat stored in hump WATER –Can go 3-4 days without water –Concentrate urine 9-fold over plasma –Doesn’t sweat (mostly) –THE NOSE Huge surface area—used for evaporative cooling Can close nostrils to save water HYGROSCOPIC BRAIN FUNCTION T a (air temp) can exceed 50ºC (138 F) Normal mammalian body temp = 37ºC How do they cope????

28 How do camels manage to live in the desert heat? Body Temp can increase 6C … But Brain can ’ t function at that temp Arterial vessel Venous vessel Heat exchange Rete mirabile “ wonderful net ” …? = Counter Current Exchange THEY KEEP THEIR BRAIN COOL!

29 Rete mirabile “ wonderful net ” Evaporative cooling

30 Rete mirabile brain temperature remains lower

31 CAMELS BODY HEAT REGULATION –Thick Fur –Body Heat to 41 ºC –Fat stored in hump WATER –Can go 3-4 days without water –Concentrate urine 9-fold over plasma –Doesn’t sweat (mostly) –THE NOSE Huge surface area—used for evaporative cooling Can close nostrils to save water HYGROSCOPIC BRAIN FUNCTION –Rete Mirabile Allows for brain cooling in spite of very high body temp T a (air temp) can exceed 50ºC (138 F) Normal mammalian body temp = 37ºC How do they cope????

32 Thermal Strategies Ectotherms: a body temperature principally dependent on external heat sources Endotherms: a body temperature principally dependent on internally generated metabolic heat Homeotherms: body temperature kept constant Poikilotherms: body temperature varies

33 ENDOTHERMS ECTOTHERMS POIKILOTHERMYHOMEOTHERMY TaTa TbTb MR TaTa TbTb Terrestrial Birds and Mammals Most Marine Fish Most Amphibians and Reptiles Polar Marine Fish A few fish A few Amph and Rept Freshwater Fish Brooding Python Some small birds and mammals Shivering Python

34 Temperature Basics Heat Transfer –Conduction –Convection –Radiation –Evaporation Example: Camels are cool!!! Thermal Strategies –Endotherm vs Ectotherm –Homeothermy vs Poikilothermy Thermal Tolerance

35 Temperature Performance Thermal performance curves: Preferred Body Temp

36 Temperature Performance Thermal performance curves: Preferred Body Temp Environmental Temperature shift? ACCLIMITIZATION!!

37 Temperature Tolerance Acclimitization –Biochemical Membrane dynamics Enzyme types and concentrations Heat Shock Proteins Behavioral Morphological Physiological Will discuss in hot vs. cold

38 Membrane Dynamics What are the kinks?

39 Polyunsaturated Fatty Acid (Omega 6)

40 Temperature also has major effects on cell membrane fluidity If you live in hot climate, what sort of fatty acids should you have? If you live in cold climate, what sort of fatty acids should you have? SpeciesBody Temperature o C Ratio of sat. to unsat. fatty acids in phospholipid Arctic Sculpin00.59 Goldfish (acclimated to 2 temps) Desert Pupfish Rat371.22

41 Diet very high in unsaturated fats Common Shingleback Cage Floor temperature Normal Diet

42 Temperature Performance Thermal performance curves: Preferred Body Temp Environmental Temperature shift? Increase PUFA in diet!

43 Enzymes = different forms of particular enzymes with different temperature optima  isozymes 4 different forms of ATPase Each with a separate thermal performance curve

44 Enzymes Alligator lizard Fence lizard Desert Fringed Lizard Desert Iguana  isozymes

45 Heat Shock Proteins Under High Temperatures, Proteins unfold (denature) How can you protect Cells during protein denaturation?

46 “Heat Shock Proteins” protect against heat damage  = proteins synthesized in response to cellular stress (including high temps)  function as “molecular chaperones” Protein denatures from Heat Heat increases HSP expression increases (more HSP) HSP binds up denatured protein Heat decreases HSP lets go, protein can refold

47 Cataglyphis Ants Other insects stop foraging Cataglyphis spend minutes In the tunnel to the nest, making heat shock proteins to protect their cells while they are out on the desert foraging >50C on sand 45C in nest entrance <30C inside nest

48 Temperature Acclimatization Biochemical –Membrane dynamics Colder? Incoporate more PUFA Hotter? Use less PUFA –Enzyme types and concentrations Colder or hotter? Change isozyme Goldfish Swimming Speed

49 Temperature Acclimatization Biochemical –Membrane dynamics Colder? Incoporate more PUFA Hotter? Use less PUFA –Enzyme types and concentrations Colder or hotter? Change isozyme –Heat Shock Proteins Protect protein denaturation from killing cells

50 Temperature Basics Heat Transfer –Conduction –Convection –Radiation –Evaporation Example: Camels are Cool!!! Thermal Strategies –Endotherm vs Ectotherm –Homeothermy vs Poikilothermy Thermal Tolerance –Acclimatization of membranes and enzymes

51 Temperature Outline Definitions: –Heat Transfer Ex: Camels are Cool!!! –Physiological strategy: endo, ecto, etc. –Temperature tolerance Extreme Temperature: COLD –Death? –Avoidance strategies –Tolerance strategies Extreme Temperature: HEAT –Death? –Avoidance strategies –Tolerance strategies

52 COLD What causes death? Avoidance Strategies Tolerance Strategies

53 What causes cold death? Intracellular ice formation o C terrestrial, -1.7 o C marine Chemical reaction rates drop CNS control, integration reduced

54 COLD What causes death? –Intracellular ice –Low enzymatic reactions –CNS control Avoidance Strategies Tolerance Strategies

55 Avoidance Hibernation/torpor

56 Significantly lowered T b Avoidance Hibernation/torpor Body Temperature Time of day Daytime temp

57 COLD What causes death? –Intracellular ice –Low enzymatic reactions –CNS control Avoidance Strategies –Hibernation/Torpor Tolerance Strategies –Behavioral –Physiological –Extreme Cold adaptations

58 Change conduction, convection, evaporation and radiation Tolerance Strategies: 1 (behavioral)

59 Countercurrent can be used to retain heat… Countercurrent heat exchangers also help keep animals warm… Tolerance Strategies: 2 (physiological)

60 Countercurrent heat exchangers Or countercurrent can be bypassed to lose heat

61 But what happens below 0 O C? occasional pulses of blood to feet prevent tissue damage Countercurrent heat exchangers

62 Shivering keep body temp elevated 5 o C nearly 9X increase in MR! Shivering Thermogenesis warm up flight muscles Tolerance Strategies: 2 (physiological)

63 Non-shivering thermogenesis (mammals) BAT = Brown adipose tissue Oxidation of BAT produces heat, but not ATP neonatal animals some cold acclimated mammals hibernators during arousal - highly vascularized - abundant mitochondria Tolerance Strategies: 2 (physiological)

64 COLD What causes death? –Intracellular ice –Low enzymatic reactions –CNS control Avoidance Strategies –Hibernation/Torpor/Estivation Tolerance Strategies –Behavioral: alter heat transfer properties Conduction, convection, radiation –Physiological Counter-current exchange Shivering thermogenesis Non-shivering thermogenesis –Extreme Cold adaptations

65 Extreme Cold! (ectotherms) Avoid FreezingTolerate Freezing

66 How do some ectotherms deal with extreme cold? Avoid Freezing Option 1: use antifreeze compounds  colligative antifreezes = lower freezing point by colligative properties e.g., glycerol, sorbitol, mannitol  Non-colligative antifreezes = lower freezing point b/c of special chemical properties

67 Non-colligative antifreezes: Glycoprotein - polar groups; bind to ice crystals & prevent their growth (lowers the temp at which ice crystals enlarge)

68 Non-colligative antifreezes: expression of genes for antifreeze protein increase seasonally… …and freezing point decreases seasonally in winter flounder.

69 Antifreeze—colligative and non-colligative } colligative } non-colligative

70 How do some ectotherms deal with extreme cold? Avoid Freezing Option 1: use antifreeze compounds Option 2: supercooling * -with gradual cooling, a liquid may remain unfrozen well below its freezing point… -…in the absence of ice nucleating agents * Lowers the temperature at which ice crystals form

71 Tolerate Freezing Option 3: promote extracellular ice formation… How do some ectotherms deal with extreme cold? Avoid Freezing Option 1: use antifreeze compounds Option 2: supercooling

72  animals must remain inactive  ice formation is restricted to extracellular fluid As ECF freezes… Water drawn from cell Ice nucleating agents promote freezing Promoting extracellular ice formation (65% frozen)(70% frozen) (50% frozen)

73 Wood Frog: Freeze Tolerant Becoming Frozen:Unfreezing: Freeze from outside inThaw evenly Dark areas are frozen Why?

74 COLD What causes death? –Intracellular ice –Low enzymatic reactions –CNS control Avoidance Strategies –Hibernation/Torpor/Estivation Tolerance Strategies –Behavioral: alter heat transfer properties Conduction, convection, radiation –Physiological Counter-current exchange Shivering thermogenesis Non-shivering thermogenesis –Extreme Cold adaptations Freeze avoidance: antifreezes (colligative and non-colligative) Freeze Tolerance: promote extracellular ice formation

75 Temperature Outline Definitions: –Heat Transfer Ex: Camels are COOL!!! –Physiological strategy: endo, ecto, etc. –Temperature tolerance Extreme Temperature: COLD –Death? –Avoidance strategies –Tolerance strategies Extreme Temperature: HEAT –Death? –Avoidance strategies –Tolerance strategies

76 HEAT What causes death? Avoidance Strategies Tolerance Strategies

77 Disruption of membrane integrity Exceeding optimal temp for enzyme function What ultimately causes heat death? temperature optima vary by species Acetylcholinesterase

78 Disruption of membrane integrity Exceeding optimal temp for enzyme function What ultimately causes heat death? Protein Denaturation

79 HEAT What causes death? –Membrane disruption –Enzyme function –Protein denaturation Avoidance Strategies Tolerance Strategies

80 Estivation = ‘summer sleep’ Metabolic rates reduced Thermal tolerance limits expanded Growth and reproduction cease Animal becomes relatively unresponsive to external stimuli Migration Spend part of the year in different location Avoidance Strategies

81 Alter Heat Transfer Properties Decrease conduction from warm surfaces Increase Convection Increase Evaporation Decrease Radiation Intake Tolerance Strategies: 1 (behavioral)

82 Locate appropriate microclimate Burrowing High evaporation FIND SHADE! Tolerance Strategies: 1 (behavioral)

83 Change Color Change Foraging strategy Change Effective Surface Area ants Tolerance Strategies: 1

84 Tolerance Strategies: 2 (physiological) Vasodilation -promotes heat loss

85 Tolerance Strategies: 2 (physiological) Evaporative heat loss Even cicadas “sweat”! accelerated water loss for evaporative cooling at 41 o C replenish with plant juices Vasodilation

86 Without rest, this rabbit will die of heat exhaustion, but the dog can keep on running… HOW? Tolerance Strategies: 2 (physiological)

87 Rete mirabile Countercurrent heat exchanger Arterial vessel Venous vessel Heat exchange “ wonderful net ”

88 Rete mirabile “ wonderful net ” Evaporative cooling

89 Rete mirabile Who has it? CatSheepDogRat primates rabbits ?? ungulates

90 HEAT What causes death? –Membrane disruption –Enzyme function –Protein denaturation Avoidance Strategies –Estivation –Migration Tolerance Strategies 1. Behavioral: Alter heat transfer properties Locate appropriate microclimate Change color Change foraging strategy Change effective surface area 2. Physiological: Vasodilation Sweating Rete mirabile

91 Temperature Outline Definitions: –Heat Transfer Ex: Camels are COOL!!! –Physiological strategy: endo, ecto, etc. –Temperature tolerance Extreme Temperature: COLD –Death? –Avoidance Strategies –Tolerance Strategies Extreme Temperature: HEAT –Death? –Avoidance Strategies –Tolerance Strategies

92 Migration Routes

93


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