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Learning Intentions

Learn about the main homeostatic control mechanism and why maintaining a constant body temperature is crucial for our health. Understand the role of the hypothalamus, skin, and thermoregulation in temperature regulation. Enhance your knowledge by exploring real-life scenarios and participating in interactive activities.

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Learning Intentions

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  1. Learning Intentions • I understand the main homeostatic control mechanism and the reasons why we need to maintain a constant environment. • I can explain the term homeostasis in terms of a sensor, an integrating centre and the effectors. • I can explain how homeostasis works to regulate body temperature. Success Criteria • I can explain the process of homeostasis in the control of body temperature if it varies from the norm. • I can state that the hypothalamus of the brain is where the body's "thermostat" is found. • I can describe the role of the skin in temperature regulation, with reference to sweating, skin hair and blood flow to the skin. • I can use a thermometer to take my own temperature.

  2. What you need to do: • On the body diagram state 3 things your body needs to remain stable • Do not discuss your list with the person sitting next to you • Discuss your list with the person sitting next to you expand your list to five things (you can work together for this bit) • Decide between you which thing is the most important for your body to keep in balance and why? • Be prepared to share your answers with the class

  3. What you need to do: • Look at each of the scenarios • For each write 2 things that are changing in the body. • 1 point for each answer that matches mine 

  4. EXAMPLE Drinking Cold Water Volume of water in blood increased Body temperature decreased

  5. Free diving

  6. Standing on top of Mount Everest

  7. Sunbathing in Miami

  8. Drinking Alcohol

  9. Running a marathon

  10. What does it mean? Homeostasis comes from the Greek and means “staying the same” Maintaining a constant internal environment. Claude Bernard (1813-1878)

  11. Control Your body is trying to maintain a constant internal environment. This is called Homeostasis. Why?

  12. Homeostasis Conditions inside your body need to be kept steady so that cells can function properly. Therefore, a balance between what goes in and what comes out needs to be maintained.

  13. Homeostasis – Example Levels of Carbon Dioxide. • Respiration in cells produced carbon dioxide constantly, which needs to be removed. Too much can lower the pH and make it too acidic. • Lower pH would therefore affect enzymes. • It is removed in the air we breathe out.

  14. How? The body regulates the environment through a process called ‘negative feedback’. • The body detects a change in the environment. • This triggers a response that counteracts the change (e.g. rise in body temperature causes a response which lowers the body temperature). • Therefore, the internal environment stays at the norm (the level that cells work best) This only works within certain limits – if the change is too great then it may not be possible to counteract – hyperthermia, heatstroke.

  15. Negative Feedback

  16. Our bodies use behavioural and physiological methods to control our temperature. Behavioural = change clothes, cold drink Physiological = sweating, goose bumps

  17. All automatic control systems including the ones in your body have three parts 3. Effector 1. Receptor 2. Processing Centre Example: automatic lights Sensor Computer chip Light bulb

  18. Body temperature Q: What is normal body temperature? A: 37C Q: What chemicals help to aid digestion? A: Enzymes Q: At what temperature, do enzymes work best? A: 37C

  19. Body temperature This can rise due to: • Exercise • Fevers due to disease • External temperature changes.

  20. Body temperature 370C is body temperature and it needs to be kept constant. If it rises too much enzymes will become denatured and no longer work, cell may die. The brain has its own personal thermostat – the hypothalamus contains receptors sensitive to blood temperature – thermoregulatory centre. It also receives feedback from the skin – can detect changes as small at 0.5C.

  21. Your skin

  22. When you get too COLD! • Hairs (B) stand up on end (to trap air which provides an insulating layer) 2. Very little sweat is produced 3. Blood vessels near surface constrict (C) (so less heat can be transferred from the blood to the surroundings). 4. You shiver (movement generates heat in the muscles) 5. You can put on more clothes.

  23. When you get too HOT! • Hairs lie flat • Lots of sweat (E) is produced (when sweat evaporates it transfers heat from you to the environment) • Blood vessels close to the surface (F) of the skin dilate (open) to allow more blood to the surface. (transfers heat from the blood to the surroundings) 4. You may take off clothes to help cool down.

  24. Extension: Give a reason for each piece of advice survival advice. Have these men followed the advice? • SAS survival advise: • Avoid exertion • Stay with your car • Stay in the shade • Don’t lie on the ground • Don’t eat • Talk as little as possible. • Breathe through your nose rather than your mouth.

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