2 Do you think ‘The Iceman’ can really will himself to be warmer Do you think ‘The Iceman’ can really will himself to be warmer? In the next 30 sec, list 5 things you might do to try and warm up if you were him…
3 Share your list with a partner… Are there any similarities? Any things you didn’t think of?
4 How is that animals are able to maintain their temperature in a range of environments?
5 Ectotherms Usually at the temperature of their environment Do not have an internal method of heat productionLower energy needs and cells function so slowly at low temperatures they are often inactive during winter
6 Ectotherms DISADVANTAGES ADVANTAGES Less active in cooler temps May not be capable of activity during winter due to the need to hibernateEctothermsADVANTAGESUse less food in respirationNeed less foodCan use more energy from food for growth
7 Heterotherms Some ectotherms can sometimes function as endotherms Allows animals to be more active
8 Endotherms Maintain a relatively constant body temperature Usually higher than their surroundingsGenerate heat by internal metabolic heat productionHave mechanisms by which to regulate loss/gain of heatEndotherms
9 Endotherms ADVANTAGES Constant temp. DISADVANTAGES Active in cold temp.Can inhabit colder countriesEndothermsDISADVANTAGESLots of energy used to regulate body temp.More food neededLess energy from food goes into growth so more food needed
10 Regulatory mechanisms These include structures:FeathersFurFatPhysiological mechanismsHibernation
11 A note on terminology…“Cold-blooded” is not correct – their blood will be warm when the environment is warm.“Warm-blooded” is also not correct – a hibernating bat maintains its temperature at about 10 °C.
16 Sensing: Detecting temperature change Involves disturbance and misalignment detectorsTemperature receptors in skin (disturbance)Misalignment detectors in the hypothalamusGroup of temperature sensitive cells trigger homeostatic responses if blood temperature deviates
17 Responding: regulating heat exchange Heat loss Radiation Evaporation Conduction Loss of body fluids To the environment Heat gain Metabolism Environmental & behavioural
18 In a cold environment…We must conserve body heat and gain heat to maintain body temperatureVasoconstriction – blood vessels near the surface of the skin narrow, reducing the volume of blood near the surface, reducing the heat lost to the environment from the bloodShivering – Muscles contract to produce heat via metabolic reactionsHair-raising – muscles in the skin at the base of each hair contract, raising hairs and trapping air, forming an insulating layer.Increased metabolic rate – respiration increases to generate more heatSweating reducedBehavioural mechanisms – huddling, sheltering
19 In a hot environment…We must lose body heat to maintain our core temperatureVasodilation – Blood vessels near the surface of the skin dilate and increase in volume, allowing more blood to flow through, radiating heat away through the skinSweating – water evaporates from the surface of the skin, using heat energy to turn the liquid into water vapour. Prevalent in humans as we lack body hair. In other mammals this takes place from the tongue and mouthBody hair flattening – removes the insulating layerBehaviours – not performing metabolic activity, sheltering
20 Why do we go pink when we are hot? For you to think about…Why do we go pink when we are hot?
22 Over to you…On a piece of paper, list 2 mechanisms the body can use to regulate temperature in a hot environment and in a cold environment…
23 Your homework task!Compare and contrast a central heating system with your body’s temperature control system. What type of feedback control regulates both these systems?Using Inspiration, illustrate both negative feedback loops involved in thermoregulation. Be sure to include Stimulus, Receptor, Regulator, Effectors. Be detailed and clear. It is up to you whether you present this as a flowchart, picture or concept map!