TEMPERATURE REGULATION

TEMPERATURE REGULATIONObjectivesList the main mechanism of heat gain and heat loss in human

Briefly describe the physiological response to an increase/ decrease in body temperatureBody TemperatureNormal internal body temperature is 370C.Temperatures above this:denature enzymes and block metabolic pathwaysTemperatures below this:slow down metabolism and affect the brain.

3Heat BalanceHeat balance maintains the body temperature

Balance between heat production & heat loss

Heat Balance Heat production= Heat loss

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.131) receptorsensor that responds to changes (stimuli)2) control centresets range of values, evaluates input and sends output3) effectorreceives output from control centre and produces a response3 basic components of a feedback system14Body Temperature ControlThe 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.15

Vasoconstriction and Vasodilatation

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Correction of overheatingDetected by thermoreceptors in the hypothalamus.Causes vasodilation.Sweating

21Correction of overcoolingDetected by thermoreceptors in the hypothalamus.Causes vasoconstriction.Decreased sweatingShivering

22Voluntary 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.

23Thermoregulatory regulatory responsesExposure to ColdShiveringIncrease voluntary activityIncrease TSH secretionIncrease CatecholaminesVasoconstrictionHorripilationCurling up

Exposure to HeatVasodilatationSweatingIncrease in RespirationAnorexiaApathyDecrease TSH secretion

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