1. Chapter 6 Barriers of the Body Interfaces with the outside

2. Barriers of the Body Skin, Lungs, and Digestive System The controlled exchange of molecules and heat Warm blooded animals are very expensive Rapidly turning over cells Damage repair

3. The Skin The surface barrier of the Body –Skin cells –Replacement skin cells –A few hairs –Sweat glands –Nerves (information: touch, temperature, and pain)

4. Heat, what is it? Heat Capacity Heat Transfer

5. Control of Body Temperature Information in to the brain >Surface sensors: “I feel hot or cold” >Temperature of blood circulating to the brain

6. Why is Heat Important? 106° F: Fried Brains 86 ° F: Dysfunctional Brain unable to warm its self Rate of reactions is a function of temperature Reactions are energy transfer among molecules To much heat destroys large molecules

9. Heat Exchange Three Processes –Radiation –Conduction –Evaporation

10. Radiation Put something in between and it is blocked

11. Conduction Moves heat around the body and to the surface of the body Molecules of water bumping into each other Sweat is water containing heat that can be “thrown away”

12. Evaporation and Convection Colder, DRY Air Warmer, Moist Air Evaporation Warmer, Moist Air Evaporation Colder, DRY Air

14. Temperature Regulation

15. Drunk

16. Lungs Gas exchange Composition of Air –78% Nitrogen (N 2 ) –21% Oxygen (O 2 ) –.04% Carbon Dioxide (CO 2 ) –Traces of other gasses

17. Breathing

18. Bronchial Tree

19. Hemoglobin >Binds O 2 >The concentration of O 2 controls the ability of Hb to bind O 2  Only free O 2 plays in the concentration game  Only free CO 2 plays in the concentration game  Molecules flow from a high concentration to a low concentration

20. Sinks A sink is a way to remove O2 and CO2 from the concentration game Oxygen sink 2O 2 + Hb HbO 4 Carbon Dioxide Sink CO 2 + H 2 O H 2 CO 3 H + + HCO 3 -

21. Lungs: Gas exchange Blood

22. Tissues: Gas exchange Water around cells Blood in capillary

23. Control of Respiration

24. Other Factors Stress: Open airways, increase depth of breathing, increase blood flow pH: drug or condition that changes blood H + concentration Drugs: Any drug that depresses brain function

25. Digestion

26. Digestive System > What we put in Protein, fat, carbohydrate, vitamins, minerals, water > Three processes Movement Breaking up big molecules Absorption into blood

27. Mouth Why your mother told you not to talk and eat at the same time

28. Stomach More water plus H + Cl - Digestive enzymes that are “ turned on” by H + H + destabilizes bonds in protein between amino acids

29. Small Intestine Put in OH- to neutralize H + H + + OH - H 2 O “Turns off” protein digestive enzymes Fat digestion: bile salts make oil and water mix Absorption into blood

30. Absorption Sifting the stream for molecules and other nutrients Nutrient filled blood goes to the liver (Hepatic Portal Vein)

31. Large Intestine Additional digestine by bacteria Water recovery

32. Control of Digestive System If you eat and when you eat What you eat Movement Release of secretions Distribution of Blood

33. Problems with Digestion Excessive stomach acid –Mild: heartburn –Severe: ulcers Drugs Antacids: H + + OH - H 2 O, disturbs blood pH, acid rebound Tagamet, Pepcid etc: Antihistamine that blocks production of HCl

34. Other Problems with Digestion Malabsorption (small intestine) eg celiacs disease an autoimmune disease People do not spend enough time on digestion and absorption Many drugs cause acid production: coffee, tea, coke, alcohol, heart medicine Antibiotics can kill the “good” bacteria in the large intestine