Human Body Responses To the environment

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Homeostatis Introduction. You will be able to. Lesson Objectives By the end of the lesson I can: Plan and implement an investigation Recall how environmental conditions affect the human body Explain how the body controls its internal environment. Human Body Responses To the environment. - PowerPoint PPT Presentation

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  • Human Body Responses To the environmentLesson ObjectivesBy the end of the lesson I can:Plan and implement an investigation Recall how environmental conditions affect the human bodyExplain how the body controls its internal environmentYou will be able to

  • Key WordsVasodilationVasoconstrictionHomeostasisPiloerectionDilate Capillaries

  • Blood vessels vasodilate so more blood is carried to surface to lose heat.Blood capillaries vasoconstrict so less blood is carried near surface to keep in heatSweating is reducedSweating is increasedHairs stand up to trap warm air to act as an insulatorHairs lie flatNo shiveringShivering muscle action produces heat from respiration Put these events into order they occur

  • Internal conditions that are controlled include;Water contentIon contentTemperatureBlood sugar level

    Water is leaving the body all the time as we breathe out and sweat. We lose any excess water in the urine (produced by the kidneys). We also lose ions in sweat and urine.

    We must keep out temperature constanst otherwise the enzymes in the body will not work properly, if at all.Sugar in the blood is the energy source for cells. The level of sugar in our blood is controlled.

  • How does the body stay cool?> SweatingWhen you are hot, sweat glands are stimulated to release sweat.Heat energy from your skin is used to turn the liquid sweat into gas - sweat evaporates.Because heat is lost, your skin cools down. > See this in action

  • How does the body stay cool?> SweatingSkinHeat lost as sweat evaporatesHeat

  • How does the body stay cool?> VasodilationYour blood carries most of the heat energy in your body.There are small blood vessels called capillaries just underneath your skin.When you are hot, these capillaries get wider (dilate) so more blood comes close to the surface of the skin and heat is lost. This is why some people go red when they are hot!> See this in action

  • How does the body stay cool?> VasodilationSkinCapillariesHeat loss

  • How does the body stay warm?> VasoconstrictionThis is basically the opposite of vasodilation.When you are cold, the capillaries near the surface of your skin get narrower (constrict) and some shut off.This means less blood comes near the surface of the skin and less heat is lost.This is why your fingers and toes might go white when they are cold!> See this in action

  • How does the body stay warm?> VasoconstrictionSkinCapillariesLess heat loss

  • ARGH!

  • What do birds do to keep warm when it is cold?I was not scared! (phew!)

  • How does the body stay warm?> PiloerectionWhen you are cold, the hairs on your skin stand up.The hairs trap a layer of air next to the skin, which is warmed by body heat and becomes an insulating layer.This is sometimes called goose bumps.The same principle applies to birds or mammals fluffing themselves up.> See this in action

  • How does the body stay warm?> PiloerectionSkinHairsTrapped air forms insulation

  • Aim: The effects of insulation on heat lossEquipment: 2 conical flasks of the same sizeBoiling waterCotton wool2 thermometersTimer or clockGraph paper

    Method: Obtain 2 conical flasksWrap cotton wool round one flask and leave the other uncoveredPour the same amount of boiling water into both flasksPlace a thermometer in each and record the temperature at 1 min intervals for 15 minsRecord results in a suitable table and plot a graph (put temperature on the vertical axis and time on the horizontal axis)

  • What makes a good graph?

    Use a Sharp Pencil and a Ruler Label the axes with Quantity and Unit (e.g. Time / minutes) The scale on each axis must use up more than half of the graph paper

    For line graphsPlot your points with crosses (X)

  • What is wrong with this graph?

    Chart2

    88

    77

    20

    66

    55

    Temperature

    Time

    Temperature

    A Line graph to show the effect of environmental conditions on Alien body temperature

    Sheet1

    Sheet2

    time246810

    temperature6767564534

    Sheet3

    TimeTemperature

    288

    477

    620

    866

    1055

    Sheet3

    0

    0

    0

    0

    0

    Temperature

    Time (mins)

    Temperature C

    A Line graph to show the effect of environmental conditions on Alien body temperature

  • Results AnalysisWhat did you measure? What did your results show?

    Conclusion:What did you find out? How does this link in with vasodilatation and vasoconstriction?What effect did insulation have on the rate of heat loss? Which flask lost heat faster and why? Which structures in the mammal do you think acts in the same way as the cotton wool?

    EvaluationHow could you improve your experiment?Was this a fair test? Were the results accurate? What improvements could be made to further improve the reliability of results?

  • HOMEOSTASIS researchGo tohttp://www.teachersdomain.org/resource/tdc02.sci.life.reg.bodycontrol/

    Read the text on the right hand side then Press VIEW

    HAVE YOU GOT WHAT IT TAKES TO CONTROL YOUR BODY MANUALLY?

    Use the internet to research -how the body is controlled, -why its important and -how it occurs.

    You should include water, ion, temperature and blood sugar levels.

    Place your research into a self-designed table on the computer and save it.

  • Human Body Responses To the environmentLesson ObjectivesBy the end of the lesson I can:Plan and implement an investigation Recall how environmental conditions affect the human bodyExplain how the body controls its internal environmentYou will be able to