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Unformatted text preview: 1 Animal Physiological Ecology – Exam 2 Study Guide Chapter 9: Thermal Relations – - Bumblebee Example: o Flight muscles determines how much power they can generate o Flight muscles must be at least as warm as about 35 degrees Celsius to produce enough power to keep the bee airborne; a bee with cooler flight muscles cannot fly o To maintain flight muscles at a high enough temp to fly, bee must expend food energy to generate heat to warm the muscles o Must expend energy at an elevated rate even during the intervals when it isn’t flying, either to keep its flight muscles continually at a high enough temp to fly or to re-warm the flight muscles to flight temp if they cool while feeding o Assuming flight muscles must be at 35 degrees Celsius for flight, they must be warmed to 10 degrees above air temp if the air is at 25 degrees, but to 30 above air temp if the air is at 5 degrees o As the air becomes cooler, a bee must expend food energy at a higher and higher rate to generate heat to warm its flight muscles to flight temp, meaning it must collect food at a higher and higher rate- Our rate of energy expenditure depends in part on how rapidly we must produce heat to keep our bodies warm, and the temps of our tissues help determine how our tissues perform- If an animal’s tissues are warmed by its metabolic production of heat, the animal is said to exhibit endothermy- Thermoregulation refers to the maintenance of a relatively constant tissue temp- Ectotherms – thermal conditions outside their bodies determine their body temps o Also called Poikilotherms – because they have variable body temps o Body temps are high in warm environments and low in cool ones- Poikilotherm or ectotherm may or may not exhibit thermoregulation- When poikilotherm displays thermoregulation, it does so by behavior o It keeps its tissues at a certain temp by behaviorally choosing to occupy environments that produce that temp in its body- Animals that warm their tissues by their production of metabolic heart – endotherms - Most endotherms exhibit thermoregulation 2- Homeotherm – animal that thermoregulates by physiological means- Under many circumstances, principal way they thermoregulate is by adjusting how rapidly they produce and retain metabolic heat: thermoregulate by modulating their endothermy- Environmental temp – aka ambient temp – is a principal determinant of an animal’s MR and, therefore, the rate at which the animal must acquire food- Temp of an animal’s tissues plays a principal role in determining the functional properties of the tissues and tissue constituents o Tissue temp also affects the rates of biophysical processes, the rates of biochemical reactions, and the viscous physical states of cellular materials such as cell-membrane phospholipids- Temperature of a substance is a measure of the speed – or intensity – of these incessant random motions- Heat is a form of energy; is the energy that a substance possesses by virtue of the random motions...
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This note was uploaded on 11/08/2010 for the course 704 360 taught by Professor John-alder during the Fall '10 term at Rutgers.
- Fall '10