LIFE 103 1st Edition Lecture 29 Outline of Last Lecture II. BiomimicryIII. Form and functionIV. Physical constraintsa. HydrodynamicsII. Evolutionary constraints a. Vertebrate flight III. Form and functionIV. Cursorial locomotionOutline of Current Lecture V. Evolutionary constraintVI. ThermoregulationVII. HomeostasisVIII. Generating and retaining heat IX. Energy conservationCurrent LectureRegulating internal environments: homeostasis and thermoregulationEvolutionary constraintI. In contrast to the engineer, evolution does not produce innovations from scratch. It works on what already exists, either transforming a system to give it a new function or combining several systems to produce a more complex one. Natural selection has no analogy with any aspect of human behavior. If one wanted to use a comparison, however, one would have to say that this process resembles not engineering but tinkering.” Francois Jacob II. Clicker question: Explain the difference in ear size between African and Asian elephants in terms of functional trade-offs (costs/benefits). African elephants are often found in arid savannas, Asian elephants in wet forests. African elephants have larger ears to help dissipate heat in their hot habitats Body mass, lifespan, and metabolic rateThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.I. The larger an organism, the longer it takes for it to metabolically process it II. Two exceptions: naked mole rat and batsIII. Relationship: basal metabolic rate to life span IV. “Living” theory: the faster you live ThermoregulationI. Biochemical reactions are temperature sensitive, so small changes in temperature can have profound effects on metabolic processes. (Homeostasis is desirable)II. Thermal conductivity of water and air are very differentIII. Thermal conductivity = ability of a material to conduct heatIV. Air has high thermal conductivity V. Water has low thermal conductivity VI. How does this impact aquatic vs. terrestrial animals? VII. Conformers (stay temp as surroundings) vs. regulators HomeostasisI. How is it maintained? II. Set pointIII. StimulusIV. Sensor/control centerV. ResponseVI. Examples:I. SweatingII. Behavioral regulationThermoregulationI. Endotherm (generates metabolic heat)I. Ex: mammals and birds II. Homeotherm (*relatively* constant temperature)III. Ectotherm (use environmental heat)I. Ex: insects, frogs IV. Poikilotherm (variable temperature) Generating and retaining heatI. Some ectotherms use shivering thermogenesis to generate heat II. Behavioral heat absorption- basking, collecting heat from the environment III. Insulation helps retain heat in mammals and birds I. Blubber, fur IV. Countercurrent heat exchangeI. Keeps cold blood at the bottom and warm blood at the top II. Seen with dolphins and sharks and geese V. Vasodilation and vasoconstrictionI. Changes how capillaries act to lose heat or avoid it II. Vasoconstriction: losing heat less rapidlyIII. Vasodilation: losing heat more rapidly Thermoregulation and energy conservationI. Torpor- a state of decreased physiological activityII. Small endotherms (birds and mammals) that are active, with high metabolic rates.III. Daily patternIV. Problem: how to survive unfavorable conditions? Escape or endureV. Hibernation- seasonal state of reduced physiological activityVI. Mostly mammals VII. “Set point” is greatly reduced, sometimes to nearly 0 degrees CVIII. Often accompanied by periodic arousals IX. Brumation- seasonal torpor in reptilesX. Aestivation- “summer hibernation”- often facultative DiseaseI. White nose syndrome II. Fungal disease that affects bats III. 99.9% mortality
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