2. The Respiratory System Pulmonary Anatomy and Physiology Chapter 15: 393-423

3. What is Respiration? Closely Matched to Activity Includes: Breathing: Moving air into lungs Gas Exchange: Between lungs and blood Gas Transport: By the blood Gas Exchange: Between blood and tissues Cellular Respiration: O 2 use

4. Pulmonary Overview: Structure and Function Mechanics of Breathing Lung Volumes and Capacities Gas Exchange Gas Laws: Partial Pressures O 2, CO 2, and pH Homeostasis Control of Ventilation Special Issues: Exercise/Disease

5. The Lungs and Homeostasis! The primary effector in Maintaining constant blood gases: O 2 CO 2 pH (H+ and HCO 3 - ) You Guessed it! Exercise causes a blood gas homeostatic emergency!

6. Pulmonary Anatomy Upper Respiratory Tract: Nose, Nasal Cavity,Pharynx etc. Lower Respiratory Tract: Larynx, Trachea, Bronchi Lungs Pleural Membrane Circulation and Lymphatics

7. Structure and Function: Ventilation: Breathing – airways/respiratory muscles Gas Exchange: Interface between air/blood Alveoli Pulmonary capillaries VERY thin diffusion distance VERY great surface area

8. Assignment: Read pages 393-406 Note: How do pressure gradients affect breathing (page 402-403) What is surfactant? What is a “pneumothorax”?

9. Horace Pippin: “Cabin in the Cottonfields” 1930’s

10. Gases and Gases in Solution Oxygen is a gas! Atmospheric Gases: Concentrations: Oxygen: 21% Nitrogen: 78+% Carbon Dioxide: 0.03%

11. Concentration vs. Partial Pressure Concentration (content) reflects the relative amount of gas in a gas mixture Pressure: The force of “bouncing” gas molecules against the walls of any container (lungs, atmosphere, balloons)

12. Speaking of Balloons! Let’s fill this balloon with expired air from our lungs: What are the gases? Put in the fridge

13. Pressure and Partial Pressure Pressure: The force of ALL the gas molecules as they “bounce of the walls” Partial Pressure: The force of one particular TYPE of gas molecule as they bounce… In this room: Partial Pressure of guys vs. girls…

14. Gas Laws: The effect of T and V on P… What happens to molecular movement when they heat up? T = P What happens to the force exerted against the walls, when the walls close in? V = P

15. General Gas Law : PV = T Or: P = T/V P = 1/V P = T Let’s check out the balloon…

16. Temperature and Volume What happened to the cooled balloon? Why “Hot Air Balloons? Hot air molecules “expand”…

17. Calculating Partial Pressures The atmospheric pressure at sea level is 760 mm Hg: 21% of that pressure force is from oxygen molecules: 760 mmHg X.21 = 160 mmHg

18. Pressure and Diffusion: Gas Molecules move from levels of high pressure to lower pressure PRESSURE GRADIENT The pressure gradient of O 2 between the alveoli and pulmonary capillary DRIVE O 2 into the blood

19. Oxygen “Gradients” in the Lung: Pulmonary Capillary = 40 mmHg Alveolus = 105 mmHg When the blood leaves the lung = 105 mmHg 40 105

20. Gas Pressures: mmHg 1601054010540 0.340454045 AtmAlv Deoxy Blood Oxy Blood Tissue Cells PO2 PCO2

21. Oxygen and Tissues The relative pressures of CO 2 and O 2 drive oxygen into the tissues and CO 2 into the blood

22. Ventilation: Inspiration: Breathing in Diaphragm contracts Thorax Expands Increased Volume = Decreased Pressure compared to the air Air Moves from high to low pressures

23. Ventilation: Expiration: Breathing out Diaphragm relaxes Thorax recoils Decreased Volume = Increased Pressure compared to outside air Air moves out of the lungs

24. Surfactant: Lungs Expand: Pleural membranes pull lungs out during inspiration Alveoli Expand: Surfactant coats the inner surface of the alveoli, and reduces surface tension –which keeps the alveoli from collapsing during exhalation

25. The Purpose of Ventilation: To Get Oxygen from the atmosphere to the needy tissues Gas enters the blood only from the alveoli. The remainder of the respiratory tract is “Dead Space”

26. Gas Exchange: Efficiency Depends on: Pressure Gradients between alveoli and capillary PO 2 Solubility constant:(O2 is OK) Diffusion Distance: 2 cells thick Surface Area: All those alveoli increase the surface area of the lungs to 70 m 2

27. The Hemoglobin Assist! Hemoglobin in Red Blood Cells increases the O 2 carrying capacity of the blood Hemoglobin has a “heavy attraction” (affinity) to oxygen Hemoglobin carries ~98.5% of the O2 in the blood

28. Hemoglobin-Oxygen Dissociation Curve:

29. Carbon Dioxide: Highest in the tissues High solubility and diffusion 7% dissolved in plasma 23% combine with hemoglobin 70% combine with H 2 O CO 2 + H 2 O H 2 CO 3

30. Bicarbonate and pH At physiologic conditions (tissues): H 2 CO 3 H + + HCO 3 - So CO 2 causes a decrease in pH CARBONIC ANHYDRASE is the enzyme catalyst

31. Breathing and pH In the lung, the reaction reverses: H 2 CO 3 H 2 O + CO 2 So Exhaling blows off CO 2 … AND reduces H + RESPIRATORY COMPENSATION (of acidosis)

32. Assignment: Read Pages: 406-410 Read Lab for Monday Have a good weekend!