TEMPERATURE

1. TEMPERATURE

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

3. Temperature sets limits… Physiology Morphology Behavior performance Darwinian fitness Environment

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

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

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? Measure of intensity of heat Total KE (calories or joules) (oC, oF, K) Same temp, Different heat content 1 Calorie = energy required to raise 1g of water 1o C How many calories to heat 1g water from 25o C to 50o C? = 25 calories How many calories to heat 100g water from 25o C to 50o C? = 2500 calories

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

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

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

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

14. 2. Convection …All fluids come to rest at a solid surface Air reaches full speed Air reaches full speed = “boundary layer” Fluid speed 0 Distance from solid surface Size of boundary layer is influenced by: Thicker boundary layer, less heat loss to conduction • size (and shape) of animal • surface roughness • fluid speed (air, H2O)

15. 3. Radiation Short wavelengths ∞ Surface temperature is important: -intensity T4 Long wavelengths = transfer of heat between objects without contact Above absolute zero, all objects emit & receive radiation -hotter surface, shorter wavelengths Area of radiative surface is, too

16. 4. Evaporation =Extremely effective method of losing heat @ 35o C, it takes 580 cal to vaporize 1g of H2O! • exposure of moist surfaces • moisture gradient

17. 4. Evaporation =Extremely effective method of losing heat @ 35o C, it takes 580 cal to vaporize 1g of H2O! • exposure of moist surfaces • moisture gradient

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

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

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

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? • Thick fur: prevents heat gain • Body Heat can increase above 37ºC • 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? • Thick fur: prevents heat gain • Body Heat can increase above 37ºC • Fat stored in Hump, not under skin Why Helpful??? During cool nights, heat loss is not restricted

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

25. How do camels manage to live in the desert heat? • 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? • Can go for 3-4 days without water • 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 cm2 • Camel Nasal Passages 1000 cm2 • Called ‘nasal turbinate’ • Can open and close to save water • Nasal Membranes are HYGROSCOPIC (very cool)

27. BODY HEAT REGULATION Thick Fur Body Heat to 41ºC 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 Ta (air temp) can exceed 50ºC (138 F) Normal mammalian body temp = 37ºC How do they cope???? CAMELS

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

29. Evaporative cooling Rete mirabile “wonderful net”

30. Rete mirabile • brain temperature remains lower

31. BODY HEAT REGULATION Thick Fur Body Heat to 41ºC 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 Ta (air temp) can exceed 50ºC (138 F) Normal mammalian body temp = 37ºC How do they cope???? CAMELS

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. Some small birds and mammals Brooding Python A few fish MR MR Tb Tb Ta Ta ENDOTHERMS Terrestrial Birds and Mammals POIKILOTHERMY HOMEOTHERMY Polar Marine Fish Most Amphibians and Reptiles A few Amph and Rept Freshwater Fish Most Marine Fish ECTOTHERMS Shivering Python http://www.flickr.com/photos/smacdonald/2520515097/

34. Temperature Basics • Heat Transfer • Conduction • Convection • Radiation • Evaporation Example: Camels are cool!!! • Thermal Strategies • EndothermvsEctotherm • HomeothermyvsPoikilothermy • Thermal Tolerance

35. Thermal performance curves: Preferred Body Temp Performance Temperature

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

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

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?

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

42. Thermal performance curves: Preferred Body Temp Performance Temperature 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. Alligator lizard Fence lizard Desert Fringed Lizard Desert Iguana Enzymes • 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” Heat increases Protein denatures from Heat HSP expression increases (more HSP) HSP binds up denatured protein Heat decreases HSP lets go, protein can refold

47. Cataglyphis Ants >50C on sand 45C in nest entrance Cataglyphis spend 10-15 minutes In the tunnel to the nest, making heat shock proteins to protect their cells while they are out on the desert foraging Other insects stop foraging <30C inside nest http://www.youtube.com/watch?v=w9KDM4C1kVg&feature=related

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 vsEctotherm • HomeothermyvsPoikilothermy • Thermal Tolerance • Acclimatization of membranes and enzymes