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Organisms and Their Environment Area of Study 1: Adaptations of Organisms UNIT 2 BIOLOGY.

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Presentation on theme: "Organisms and Their Environment Area of Study 1: Adaptations of Organisms UNIT 2 BIOLOGY."— Presentation transcript:

1 Organisms and Their Environment Area of Study 1: Adaptations of Organisms UNIT 2 BIOLOGY

2 WEEK 3: Learning Outcomes By the end of the week, you should be able to:  Explain how temperature is regulated in animals (thermoregulation).

3 Some Key Terms ENDOTHERMS In-built source of body heat – their internal energy-releasing chemical reactions that produce heat energy Maintain fairly constant body temperature ECTOTHERMS Depend on external sources of heat to generate body warmth HOMEOTHERMIC Organisms with constant temperatures POIKILOTHERMIC Organisms with fluctuating temperatures

4 RADIATION transfer of heat from a hot body to a cooler one, via infra-red waves CODUCTION transfer of heat from a hotter object which is in contact to the cooler object CONVECTION transfer of heat by means of hotter air/water rising and being replaced by cooler air or water EVAPORATION process by which water changes from liquid to vapour. EXAMPLE?

5 Can you tell the temperature? STUFF TO DO! 1.Try and guess the temperatures of each container of water. 2.Write down your estimate. 3.Find out the real temperatures and record them. STUFF TO DO! 1.Try and guess the temperatures of each container of water. 2.Write down your estimate. 3.Find out the real temperatures and record them. 1.Are you good at determining an accurate temperature? 2.Why is it so important to be aware of whether you are hot or cold? 1.Are you good at determining an accurate temperature? 2.Why is it so important to be aware of whether you are hot or cold?

6 Can you tell the temperature? It could be dangerous to become too hot or too cold. A body temperature below 35°C can result in hypothermia. A body temperature above 40°C = medical emergency.

7 Controlling Body Temperature Your body temperature must be maintained at the level at which enzymes work best (around 37°C). Your skin surface temperature can vary without causing harm. It is your core body temperature that must be kept stable. Your body temperature is monitored and controlled by the thermoregulatory centre in your brain. This centre has receptors sensitive to the temperature of blood flowing through the brain. 2 2 3 3 4 4 5 5 1 1 7 7 6 6

8 Your internal body temperature can be affected by many things including: Heat produced in your muscles during exercise, Fevers caused by diseases, The external temperatures rising or falling. How can you control some aspects of your own temperature? Taking clothes off or putting them on, drinking a cool drink, turning on the heating, opening a window etc. 8 8 9 9 10

9 Cooling Down If you get too hot, your enzymes denature and can no longer catalyse the reactions in your cells. When your body temperature starts to rise, nerve impulses are sent from the thermoregulatory centre in the brain to the rest of the body. The body’s response is to lose more heat. 11 12 14 13 15

10 Cooling Down VASODILATION: The blood vessels that supply your skin capillaries, dilate (become wider). This lets more blood flow through the capillaries closer to the skin surface. The heat from the blood is then lost by radiation. Your rate of sweating is increased. Sweat is lost from your sweat glands onto the surface of the skin. The water from the sweat evaporates, taking heat from the body. 16 17 19 18 21 20

11 Warming Up If you get too cold, the rate of enzyme- controlled reactions in your cells falls too low. Your cells don’t release enough energy, by respiration, and your cells begin to die. If your core temperature becomes too low, impulses are sent from the thermoregulatory centre in the brain telling the body to conserve and generate heat. 22 23 24 25 26

12 VASOCONSTRICTION: The blood vessels which supply your skin capillaries constrict (become smaller) to reduce the flow of blood through the capillaries. This reduces heat loss through the skins surface, and so you look pale. Shivering begins. Your muscles contract and relax rapidly which involves lots of cellular respiration. This releases some energy as heat which raises your body temperature. Sweat production is reduced. 27 28 29 30 31 32 33 34 Construct a mind map to summarise the information on the previous slides. Now complete the card sort.

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14 Animals surviving in water Countercurrent exchange mechanisms are found in organs such as gills, seal fins, tuna muscles, platypus feet, fins and tails. The blood travelling in the arteries, to the platypus’ feet for example, warms the blood that is returning to the body. The outgoing blood is cooled in the process; not enough to affect cell activity, but enough so that the difference in temperature between the foot and the environment is reduced, therefore less heat is lost.

15 List some BEHAVIOURAL, STRUCTURAL and PHYSIOLOGICAL adaptations that animals have to maintain a constant body temperature.

16 Adaptations to Temperature Behaviour Move to sun Move to shade Hibernate Lick wrists Huddle Migration Burrow Structures Fur Feathers Fat SA:V ratio Piloerection Big ears Physiology Sweat Shiver Vasodilation Vasoconstriction Countercurrent exchange Adrenaline Thyroxine

17 TO DO BIOZONE : page 257 – 259


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