1. Homeostasis

2. Importance of homeostasis  Provides optimum conditions for F the efficient functioning of the F body tissues

3. Homeostasis

4. Kidney Q Regulate the amount of water and mineral salt Q removal of waste products from the body

5. The structure of kidneys It made up of three parts : 4 Cortex 4 medulla 4 pelvis

6. The structure of kidneys 4 Each kidney made up of many tubules called nephrons 4 Each kidney made up of two parts : Bowman’s capsule & collecting duct

7. How the nephron works ? 4 Ultrafiltration 4 Reabsorption

8. Role of the kidney in homeostasis 4 Osmoregulation 4 Removal of excess salt 4 Excretion

9. Skin 4 Regulation of body temperature

10. Structure of skin

13. Regulation of body temperature enzyme work best over a certain range of temperature important to keep the body temperature constant

14. Regulation of body temperature animals can be classified into two types : Poikilotherms & Homoiotherms

15. Poikilotherms  Cold blood animals  have little control over their body temperature  their body temperature vary with that of the surroundings  e.g. fish, amphibians

16. Homoiotherms  warm-blood animals  can keep their body temperatures constant irrespective of the surrounding temperature  have temperature control system  e.g. birds and mammals

17. How mammals control their body temperature?  Heat loss  heat gain

18. When the body is hot Increase heat loss  More sweat is secreted  Vasodilation  erector muscle relax  develop thinner subcutaneous fat

19. When the body is hot Reduce heat gain  decrease the metabolic activities of liver cells and the contraction of muscles cells

20. When body is cold Reduce heat loss  Vasconstriction  Erector muscles contract  sweat glands produce less sweat  develop thicker subcutaneous fat and thicker fur

21. When body is cold Increase heat gain  higher metabolic activities of liver cells and by shivering

22. Liver and pancreas 4 Regulation of blood glucose level

23. The control of blood glucose level 4 the blood glucose level is controlled by insulin  it is a feedback system

24. When Blood glucose level is too high –E.g. after a meal –pancreas secretes insulin which causes liver to convert glucose to glycogen –Blood glucose levels then falls –normal blood glucose level is then recovered

25. When blood glucose level is too low 4 E.g. a long time after a meal 4 pancreas secretes less insulin so liver converts glycogen to glucose 4 blood glucose level then rises  normal blood glucose level is recovered