1 / 59

Thermoregulation

Thermoregulation. Maintaining a stable body temperature. Why do organisms need to maintain a stable body temperature??. Optimum Temperatures. Organisms must keep their body temperature between a specific range in order to survive. Enzyme activity Metabolic processes.

kalea
Download Presentation

Thermoregulation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Thermoregulation Maintaining a stable body temperature

  2. Why do organisms need to maintain a stable body temperature??

  3. Optimum Temperatures • Organisms must keep their body temperature between a specific range in order to survive. • Enzyme activity • Metabolic processes

  4. Body Temperature in animals • There are two types of organisms that maintain their body temperature in very different ways • Ectothermic organisms • Endothermic organisms • What do these terms mean? Can you give some examples of each?

  5. Ecto (outside); therm (heat) • Use external environment to maintain body temperature. • Produce little heat • Lose heat quickly • Use less energy • Become very inactive when it gets cold • Fish, Reptiles, Insects

  6. Endo (inside); therm (heat) • Maintain relatively constant body temperature • Generate a lot of heat from within via internal heat production • Generally have insulating structure to reduce heat loss (e.g. feathers, fur, fat) • Also develop behavioural and physiological adaptations to prevent heat loss

  7. Endo (inside); therm (heat) • Mammals and birds

  8. Homeothermic: organisms that can maintain a stable body temperature (e.g. mammals) • Poikilothermic: organisms whose body temperature varies considerably due to its surroundings (e.g. reptiles and insects)

  9. Heat Transfer • Heat is a question of balance • Too HOT and animals must find ways to lose heat • Too COLD and animals must find ways to gain heat

  10. Heat Transfer • To understand why animals do the things they do you must understand how heat can be transferred. QUESTION • What are the ways in which heat can be transferred?? How can animals lose or gain heat??

  11. Heat Transfer • Conduction: transfer of heat from a hotter object to a cooler object via contact. • Radiation: transfer of heat from a hotter object to cooler object via infra-red waves.

  12. Heat Transfer • Convection: Transfer of heat by warm air, or water, rising and being replaced by cooler air or water. • Evaporation: The process of changing a liquid into a gas. The heat from the body can evaporate water and cause a cooling effect.

  13. Heat Transfer Heat transfer RAP!!!!

  14. Heat Gain and Loss • Gain • Basic metabolic processes • Shivering • Exercise or other muscular activity • Radiation and conduction to the body • Loss • Evaporation sweat • Panting • Convection • Radiation and conduction from the body

  15. Heat Loss and Gain VIDEO!!!!!

  16. Systems Involved • Thermoregulation occurs via nerves and hormones • It involves many sensory inputs and several effector responses that act together to maintain a stable temperature

  17. Linking to other systems • Thermoregulation is strongly related to the Nervous system and the Endocrine system Worksheet

  18. Investigating Sweating • What you need to know: • How does sweating affect body temperature? • Why does sweating affect body temperature? • How can models help us investigate how the body works? • Question: • How does water evaporate?

  19. For water to evaporate, it must absorb heat from its surroundings

  20. Cotton wool Dry towelling cloth • Set up the equipment as shown opposite • Fill the conical flask with hot water from the kettle • Record the temperature and start your stop clock • Record the temperature every minute for 10 minutes. Record your data in a suitable table • Repeat with a wet towelling cloth

  21. To Do: • Plot a graph of your data • Which flask cooled faster? • How do you explain your results? • Was your experiment a fair test – if not, why not? • How could you make this experiment more of a fair test?

  22. Systems Involved • Brain – Hypothalamus • Lowering or raising the temperature of the hypothalamus initiates regulatory responses • Changes occur in heat production and heat exchange • Temperature cells act as misalignment detectors

  23. Core body temperature >37°C Thermoreceptors Hypothalamus nerves Muscles of skin arteriole walls relax Sweat glands increase secretion Muscles reduce activity Skin arteries dilate More blood to the skin. More radiation & conduction of heat More water covers the skin. More evaporation Less heat generated

  24. Systems Involved • Hypothalamus responds to receptors and coordinates appropriate nerve and hormonal responses

  25. Systems Involved • The hypothalamus can release hormones that initiate the release of further hormones. • For example as the temperature drops the pituitary gland will be stimulated and release a thyroid stimulating hormone • The thyroid gland in turn produces hormones which increase the metabolic rate therefore increasing heat production

  26. Systems Involved

  27. Systems Involved • Skin – thermoreceptors act as disturbance detectors. • Detect change in external environment and triggers responses before it effects internal body temperature. • Responses include erector muscles of hairs contract and hairs stand up, blood vessels constrict. • These are the effectors for mediating change.

  28. Skin

  29. Negative feedback • Temperature regulation by the skin is part of a negative feedback system. • Output is fed back to receptors and becomes part of a new stimulus response cycle.

  30. Muscles of skin arteriole walls relax Sweat glands increase secretion Core body temperature >37°C nerves Hypothalamus Thermoreceptors Muscles reduce activity NEGATIVE FEEDBACK Blood temperature Thermoreceptors Body loses heat Return to 37°C

  31. Thermoregulation • VIDEO REVIEW

  32. Summary • Ectothermic • Endothermic • Homeothermic • Poikilothermic • Heat transfer – Conduction, Convection, Radiation & Evaporation • Heat Gain and Loss • Endocrine and Nervous system involved

  33. Review Questions • Page 256 of the text book. - Questions 17 - 21

  34. Adaptations and Thermoregulation • Apart from physiological adaptations, animals also develop behaviours and physical structures that help them regulate their body temperature.

  35. Heat Loss and Gain • Must remember the ways in which heat can be transferred. • These processes work on a temperature gradient. • Can you explain what this means?

  36. Heat Loss and Gain • Temperature gradient simply refers to the difference in temperature between two things. • For example the lizard and the rock.

  37. Heat Loss and Gain

  38. Heat Loss and Gain • The rock is warmer than the lizard so the heat moves, via conduction, from the rock to the lizard. • As the lizard heats up and the gradient decreases and eventually changes the heat moves from lizard to rock.

  39. Structural & Behavioural • The transfer of heat needs to be controlled. • What examples of structural and behavioural adaptations can you think of?

  40. Behavioural Responses • Penguins huddling • Burrowing underground • Seeking shade • Basking • Fanning from honeybees

  41. Behavioural Responses • VIDEO

  42. Counter current heat exchange

  43. Counter current heat exchange • The arteries and veins in certain areas, like the foot of the penguin, run very close to each other. • The warmer blood in the arteries heats the cooler blood in the veins.

  44. Structural Responses • Animals need to control exchange. This can also be achieved through: • Insulation: - Fur - Feathers - Fat

  45. Structural Adaptations • Feathers and fur insulate by trapping a thick layer of warm air next to the skin. • The layer of air has a protective insulating affect keeping the animal warm.

  46. Structural Adaptations • The layer of air trapped by the otters fur helps reduce the temperature gradient between the otter and its surroundings. • Therefore reducing heat loss and gain.

  47. Structural Adaptations • Blubber is also used as insulation. • Thick layers of fat are very effective in insulating animals against extremely cold conditions.

  48. Structural Adaptation • Shape and size also play an important role. • How do you think shape and size of an animals can help?

  49. Structural Adaptations • A large surface area to volume ratio increases heat loss • A small surface area to volume ratioreduces heat loss.

  50. Structural Adaptations

More Related