Homeostasis refers to the body's ability to maintain stable internal conditions such as temperature, water levels, and glucose concentration. The body has various mechanisms to regulate these conditions and keep them within a narrow range to support optimal cell function. For example, sweating and vasodilation help cool the body by increasing heat loss through evaporation and blood flow to the skin surface. Vasoconstriction and piloerection help warm the body by trapping heat near the skin. The pancreas regulates glucose levels through insulin and glucagon. The kidneys control water levels by filtering the blood and selectively reabsorbing or excreting water, ions and waste products like urea to produce urine.

1. Homeostasis

7. Sweating The skin

9. If the temperature rises, the blood vessel dilates (gets bigger). This means more heat is lost from the surface of the skin

11. If the temperature falls, the blood vessel constricts (gets shut off). This means less heat is lost from the surface of the skin

15. If there is too much glucose in the blood, Insulin converts some of it to glycogen Glycogen Insulin Glucose in the blood

16. If there is not enough glucose in the blood, Glucagon converts some glycogen into glucose. Glycogen Glucagon Glucose in the blood

18. Time Glucose Concentration Meal eaten Insulin is produced and glucose levels fall to normal again. Glucose levels rise after a meal. Normal

19. Time Glucose Concentration Meal eaten Insulin is not produced so glucose levels stay high Glucose levels rise after a meal. Diabetic

20. The glucose in the blood increases. Glycogen Insulin Glucose in the blood But there is no insulin to convert it into glycogen. Glucose concentration rises to dangerous levels.

22. The kidneys The kidneys “clean” the blood of waste products and control how much water is kept in the body. The waste products and water make up urine which is excreted via the ureter. “ Dirty” blood enters the kidney through the renal artery. Then, several things happen to clean the blood...

23. Blood enters the tubule area in a capillary. The capillary forms a small “knot” near the kidney tubule. The blood is filtered so all the small particles go into the tubule. The capillary then carries on to run next to the tubule. 1. Filtration Kidney tube Capillary

24. The kidney tubule now contains lots of blood components including: Glucose: Ions: Water: Urea: Kidney tube

25. 2. Reabsorb sugar The body needs to have sugar in the blood for cells to use in respiration. So all the sugar is reabsorbed back into the capillary.

26. 2. Reabsorb sugar The body needs to have sugar in the blood for cells to use in respiration. So all the sugar is reabsorbed back into the capillary.

27. 3. Reabsorb ions Water and ions are the next to be absorbed. It depends on how much is needed by the body.

28. 4. Reabsorb water Water and ions are the next to be absorbed. It depends on how much is needed by the body.

29. Reabsorbing water If you have too little water in your blood, you will produce very concentrated urine. (very little water in it=dark yellow) If you have too much water in your blood, you will produce very dilute urine. (lots of water in it=light yellow)

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