Presentation on theme: "Thermoregulation & Feedback How do different organisms maintain temperature balance? Warm-blooded (endotherms) Cold-blooded (ectotherms)"— Presentation transcript:
1 Thermoregulation & Feedback How do different organisms maintain temperature balance? Warm-blooded (endotherms)Cold-blooded (ectotherms)
2 Temp Regulation - Homeostasis Why must organisms maintain internal temp balance?Enzymes!!Enzymes speed up chemical rxns in your bodyEnzymes only work under certain conditions
3 Thermostat Temperature set on thermostat Too cool? Heater kicks on and temperature goes upToo warm? Stays off until house cools downConstant checking and turning on and off
4 Control of homeostasis through feedback Feedback system- cycle of events in which the status of a body condition is continually monitored, evaluated, changed, re-monitored, re-evaluated, etc.
5 3 basic components of a feedback system 1) receptorsensor that responds to changes (stimuli)2) control centersets range of values, evaluates input and sends output3) effectorreceives output from control center and produces a response
6 Body Temperature Control The hypothalamus acts as a thermostat and receives nerve impulses from heat and cold thermoreceptors in the skin.There are also receptors in the hypothalamus- called central thermoreceptors.These detect changes in blood temperature.
7 Summary What is the difference between an ectotherm and an endotherm? What are the components of a feedback system?
12 Correction of overheating Detected by thermoreceptors in the hypothalamus.Causes vasodilation.Sweating
13 Sweating How does it work? Heat energy in the body is used to convert the water in sweat to vapour cooling down the body.
14 Heat Loss Radiation: Transfer of heat via infrared rays 60% heat loss at restConduction: Heat loss due to contact with another surfaceConvection: Form of conductive heat loss
15 Heat Loss Evaporation Evaporation rate depends on Heat transferred via water (sweat) on skin surfaceEvaporation rate depends onTemperature and relative humidityAmount of skin surface exposed25% heat loss at restMost important means of cooling off during exercise
16 Correction of overcooling Detected by thermoreceptors in the hypothalamus.Causes vasoconstriction.Decreased sweatingShivering
17 Keeping warm When it's cold, the muscle contracts pulls the hair up. A layer of warm air accumulates around the hair and insulates the organism.Heat retained
19 Voluntary responsesIn humans the cerebrum “makes” people feel cold or hot.They can then e.g. put on more clothes, eat a hot meal, exercise etc as appropriate.
20 SummaryDescribe the specific pathway that is used to keep us warm. Start with the temperature receptors in the skin.Describe the specific pathway that is used to cool us off. Start with the temperature receptors in the skin.