Lecture notes chapter 40

Example large mouth bass is an osmoregulator feedback

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Unformatted text preview: temperature stays stable across a wide range of ambient temperatures * internal temperature conforms to water temperature However: animals may regulate some internal conditions while allowing others to conform to the environment Example: Large mouth bass is an osmoregulator Feedback loops maintain homeostasis: Non ­living example of nega2ve feedback: Control of room temperature _ What is the sensor? thermostat Sensor What is the signal? temperature of room Key point: NegaCve feedback funcCons to + dampens the sCmulus / shut stimulus down Homeostasis in animals relies largely on negaCve feedback Why does homeostasis not rely on posi2ve feedback – a response that amplifies the s2mulus? positive feedback systems work to drive a process to completion rather than keep it in balance Examples: 1. Child birth: signal stops when the baby is delivered 2. Gastrin sCmulaCon of gastric juices: signals stops when a bolus of food is processed to chyme and the chyme enters the SI. Thermoregula2on: the process by which animals maintain an internal temperature within a tolerable range Why is this process so important? Most biochemical and physiological processes are sensiCve to changes in body temperature (e.g. Enzyme acCvity and membrane structure change when temperature increases/decrease) Thermoregula2on Endotherm Heat Source External Environment Ectothermic Internal Metabolism Birds, Mammals Ectotherm Endothermic Example: birds are endothermic but use sun to warm themselves Amphibians, repCles, fishes, invertebrates Varia2on in body temperature: Poikilotherm: animals whose body temperature varies with the environment Homeotherms: animals with a relaCvely constant body temperature Are ectotherms always poikilotherms? No, some ectothermic animals live...
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This document was uploaded on 02/10/2014.

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