Keywords (reading p ) Controlling the Internal Environment I - Regulation of Body Temperature

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1 Keywords (reading p ) Controlling the Internal Environment I - Regulation of Body Temperature Temperature effects On reactions On lipid bilayer Endotherm Ectotherm Homeostasis Thermoregulation Behavioral thermoregulation Physiological thermoregulation Countercurrent heat exchange Shivering Effect of large size insulation Temperature Affects the rates of reactions and the characteristics of macromolecules Since organisms are machines made of macromolecules in which chemical reactions occur, temperature is an very important environmental feature Temperature affects the rates of reactions, e.g. enzyme catalyzed reaction Illustrated by gas molecules in a balloon slowing down if they are cooled Frozen tree frog fspm 1

What is the magnitude of temperature effects for physiological processes or biochemical reactions? Increase by 2-3 fold for a 10 C increase in temperature.

2 What is the magnitude of temperature effects for physiological processes or biochemical reactions? Increase by 2-3 fold for a 10 C increase in temperature. Q10 value = 2 to 3 Q10 values differ for different physiological processes or biochemical reactions Some will speed up more, some less This can ruin coordination of enzymes and reactions in metabolism, e.g., mitochondria Temperature affects characteristics of macromolecules Example: lipid bilayer Lipid bilayer Structure of an unsaturated phospholipid 2

3 Bilayer with unsaturated phospholipid stays fluid at lower temperatures Maintaining membrane fluidity at different temperatures Melting temperatures of some saturated fatty acids Melting temperature of some unsaturated fatty acids Name symbol melting T ( C) Lauric 12: Myristic 14: Stearic 20: Name symbol melting T Palmitoleic 16:1-0.5 Oleic 18: Linoleic 18:2-5.0 Linolenic 18: Ratio of saturated to unsaturated Fatty acid composition of membranes from animals acclimated to different temperatures saturated/unsaturated Class arctic sculpin rat 0 C 37 C Choline Ethanolamine Serine/inositol

Ratio of saturated to unsaturated Regulation of desaturase activity Class goldfish goldfish 5 C 25 C Choline 0.66 0.82 Ethanolamine 0.34 0.51 Serine/inositol 0.46 0.

constantly cycled into the lipid bilayer.

4 Ratio of saturated to unsaturated Regulation of desaturase activity Class goldfish goldfish 5 C 25 C Choline Ethanolamine Serine/inositol Desaturase is a membrane associated protein Under high temperature conditions, high fatty acid saturation Under low temperature, increased unsaturation Desaturase in Tetrahymena Phospholipids are constantly cycled into the lipid bilayer. Exposed desaturase will form unsaturated PLs that will then go into bilayer increasing fluidity The making of whipped cream and butter Since temperature has such a fundamental influence on biochemistry and physiology, animals: A. regulate their body temperatures so they aren t affected by temperature or can live under a wide range of conditions B. Don t regulate their temperature and accept metabolic consequences or live under small range of conditions 4

heat from metabolism When endotherms are able to regulate their temperature they are called

condition of the body Internal fluctuations are small Thermoregulation Regulation of body

5 Endotherms vs. Ectotherms Ectotherms have a body temperature the same as their environment Endotherms use heat from metabolism When endotherms are able to regulate their temperature they are called homeotherms Example of endotherm and ectotherm Homeostasis The steady-state physiological condition of the body Internal fluctuations are small Thermoregulation Regulation of body temperature Can be behavioral or physiological Behavioral thermoregulation Brandt's Cormorants, Phalacrocorax penicillatus, taking advantage of coastal morning sunlight. 5

heat exchange Arteries and veins in appendages are closely

mechanism in flippers of marine mammals Blood flow can be

6 ch?v=tmcf7snub-q Example of physiological: countercurrent heat exchange Arteries and veins in appendages are closely associated Hot arterial blood passes heat to returning venous blood. No heat is lost Blood vessels in a bird leg Similar mechanism in flippers of marine mammals Blood flow can be controlled so that heat is lost. Blood goes to alternate veins close to the surface. Countercurrent exchange is a trick used by many animals 6

7 Tuna heat exchanger Great white shark Body surface 7 5 Other tricks: shivering Non-shivering thermogenesis: brown fat Using ATP to contract muscles releasing heat instead of movement Body core Brown fat-short circuited mitochondria 5% in human infants Brown fat White fat 7

Insect preflight warmup http://www.youtube.com/watch?v=_wp2xwbhmak http://www.youtube.com/watch?v=bq5bedtzgds&feature=related http://www.

v=qsyfpiyaty4 Another trick: reduce heat loss Insulating fat (blubber) Large size - reduced surface area relative to volume

and water conducts heat faster than air thermal camera shows how difficult it is to be a little seal in the Antarctic.

8 Insect preflight warmup Another trick: reduce heat loss Insulating fat (blubber) Large size - reduced surface area relative to volume prevents heat from escaping Insulation - e.g., fur, feathers Big problem for marine mammals since they have high body temp. and water conducts heat faster than air thermal camera shows how difficult it is to be a little seal in the Antarctic. The larger red image is the mother seal who is followed by her little blue pup. Blue represents cold temperatures; red and orange are warm areas. Mom with her thick blubber layer appears much warmer than her new born pup. 8

Thermal Physiology C H A P T E R. PowerPoint Lecture Slides prepared by Stephen Gehnrich, Salisbury University

Thermal Physiology C H A P T E R. PowerPoint Lecture Slides prepared by Stephen Gehnrich, Salisbury University C H A P T E R 13 Thermal Physiology PowerPoint Lecture Slides prepared by Stephen Gehnrich, Salisbury University Thermal Tolerance of Animals Eurytherm Can tolerate a wide range of ambient temperatures