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

6. Information out from the brain >Blood flow to the surface of the body >Heat generation by the muscles >Behavior: “Are you smart enough to come in out of the cold”?

7. 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 Too 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 Evaporation

13. Temperature Regulation

14. Drunk

15. Immune Protection Macrophages (“big eaters”) –Foreign structures –Damage –Chemical messages that attract other cells of the immune system

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 In (chest expansion) Out (Chest contraction)

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 O 2 and CO 2 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 Air in alveoli Blood

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

23. Control of Respiration You only inhale if your brain tells you to Information in: H + concentration of the blood going to your head Your brain is responding to H + not O 2 Information out: Nerve signals to your diaphragm and intercostal muscles

25. 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

26. Digestion

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

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

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

30. 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

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

33. Large Intestine Additional digestion by bacteria Water recovery

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

36. 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

37. Other Problems with Digestion Malabsorption (small intestine) eg Celiac’s 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