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 production
Lower 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 hibernate
Ectotherms
ADVANTAGES
Use less food in respiration
Need less food
Can 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 surroundings
Generate heat by internal metabolic heat production
Have mechanisms by which to regulate loss/gain of heat
Endotherms

9. Endotherms ADVANTAGES Constant temp. DISADVANTAGES
Active in cold temp.
Can inhabit colder countries
Endotherms
DISADVANTAGES
Lots of energy used to regulate body temp.
More food needed
Less energy from food goes into growth so more food needed

10. Regulatory mechanisms
These include structures:
Feathers
Fur
Fat
Physiological mechanisms
Hibernation

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.

12. Explain the graph…

13. Temperature-regulating Pathways

14. Thermoregulation
Maintenance of body temperature within a range that enables cells to function efficiently
The maintenance of body temperature in endotherms is an example of dynamic equilibrium

15. Sensing: Detecting temperature change

16. Sensing: Detecting temperature change
Involves disturbance and misalignment detectors
Temperature receptors in skin (disturbance)
Misalignment detectors in the hypothalamus
Group 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 temperature
Vasoconstriction – 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 blood
Shivering – Muscles contract to produce heat via metabolic reactions
Hair-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 heat
Sweating reduced
Behavioural mechanisms – huddling, sheltering

19. In a hot environment…
We must lose body heat to maintain our core temperature
Vasodilation – Blood vessels near the surface of the skin dilate and increase in volume, allowing more blood to flow through, radiating heat away through the skin
Sweating – 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 mouth
Body hair flattening – removes the insulating layer
Behaviours – 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?

21. For you to think about…

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!