1. Homeostasis 1.Maintain – keep up. 2.Constant – the same. 3.Internal – inside the body. 4.Environment – surroundings of the body.

2. What is Homeostasis? The maintenance of a constant environment in the body is called Homeostasis

3. 1.Body cells work best if they have the correct a)Temperature b)Glucose concentration c)Water levels 2.Your body has mechanisms to keep the cells in a constant environment.

4. Dueling Mechanisms What goes up, must come down! Thermoregulation Sweating (cooling) vs. shivering (warming) Blood Pressure Vasconstriction vs. vasodilation Osmoregulation Hypotonic vs. hypertonic

5. Controlling body temperature 1.All mammals maintain a constant body temperature. 2.Human beings have a body temperature of about 37ºC. a)E.g. If your body is in a hot environment your body temperature is 37ºC b)If your body is in a cold environment your body temperature is still 37ºC

6. What mechanisms are there to cool the body down? 1.Sweating 2.When your body is hot, sweat glands are stimulated to release sweat. 3.The liquid sweat turns into a gas (it evaporates) 4.To do this, it needs heat. 5.It gets that heat from your skin. 6.As your skin loses heat, it cools down.

7. Sweating The skin

8. What mechanisms are there to cool the body down? 1.Vasodilation a)Your blood carries most of the heat energy around your body. b)There are capillaries underneath your skin that can be filled with blood if you get too hot. c)This brings the blood closer to the surface of the skin so more heat can be lost. d)This is why you look red when you are hot!

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

10. What mechanisms are there to warm the body up? 1.Vasoconstriction a)This is the opposite of vasodilation b)The capillaries underneath your skin get constricted (shut off). c)This takes the blood away from the surface of the skin so less heat can be lost.

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

12. What mechanisms are there to warm the body up? 2.Piloerection a)This is when the hairs on your skin “stand up” b)It is sometimes called “goose bumps” c)The hairs trap a layer of air next to the skin which is then warmed by the body heat d)The air becomes an insulating layer.

13. Controlling Glucose levels 1.Your cells also need an exact level of glucose in the blood. 2.Excess glucose gets turned into glycogen in the liver 3.This is regulated by 2 hormones (chemicals) from the pancreas called: InsulinGlucagon

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

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

16. Diabetes 1. 1.The blood glucose level is the amount of glucose in the blood. 2. 2.Glucose is a sugar that comes from the foods we eat, and it's also formed and stored inside the body. 3. 3.It's the main source of energy for the cells of our body, and it's carried to each cell through the bloodstream.

17. Diabetes 4.Some people do not produce enough insulin. 5.When they eat food, the glucose levels in their blood cannot be reduced. 6.This condition is known as DIABETES. 7.Diabetics sometimes have to inject insulin into their blood. They have to be careful of their diet.

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.

21. Diabetes - Hyperglycemia 1. 1.Hyperglycemia is the medical word for high blood sugar levels. High blood sugar levels happen when the body either can't make insulin

22. Diabetes - Hypoglycemia 1. 1.Low blood glucose, also called hypoglycemia, happens if your blood glucose drops too low.hypoglycemia 2. 2.Low blood glucose can be caused by missing a meal, delaying a meal, exercising more than usual, or drinking alcoholic beverages.

23. Controlling water levels 1.The control of water levels is carried out by the KIDNEYS. 2.It is closely linked to the excretion of urea. 3.Urea is a waste product that is made when the LIVER breaks down proteins that are not needed by the body. 4.Urea contains the element Nitrogen.

24. Osmoregulation Hypotonic vs. hypertonic