1. 2 December 2009 Respiratory Physiology
Lab this week: A case study and measuring lung volumes and capacities with Powerlab.
Bring calculator and textbook to lab.
About the Final Exam…..
Choice of Tuesday or Wednesday 9-noon Details of format and suggestions to be posted to website.

2. Figure 13.19
Tidal inspiration
At end of normal tidal expiration

3. V = VT x f
VA = (VT – VDS) x f
Anatomic dead space = air remaining in conducting zone (typically 150 ml.)
What is VA if Tidal Volume is 150 ml?

5. Gas Laws Dalton’s Law Henry’s Law
Total pressure = sum of partial pressures
PATM = P N2 + P O2 + P CO2
100% = 79% + 21% + <1%
P O2 = 0.21 x 760mmHg = 160
Partial pressure of Oxygen in atmosphere at sea level is 160 mmHg
N2 is physiologically inert; ignore
Gases dissolve in liquids in proportion to their partial pressure in the air in contact with that liquid
air
P O2 =160 mmHg
blood
P O2 =160 mmHg

6. CO2 production
O2 uptake

7. CO2 production
= Respiratory Quotient
O2 uptake
= 0.8 for proteins
= 0.7 for fat
= 1.0 for carbohydrates
=0.8 for mixed diet 200 mlCO2/min ml O2/min

8. Gas exchange All gases move by diffusion. Thus limited by:
Surface area
Distance
Concentration gradient
In the lung, gases must move from air to water and vice versa. The amount is proportional to
Solubility (CO2 more soluble that O2)
Temperature (colder fluids dissolve more gas)
Pressure gradient

9. Pathological limitations to diffusion

10. Alveolar to arterial gradient is due to ventilation/perfusion inequality.
Ventilation by Bulk Flow
Pulmonary Venous blood is equivalent to Systemic Arterial blood.
Gas exchange
Gas exchange
Gradient for CO2 is only 6 mmHg;
CO2 is more soluble and permeable than O2

11. Landmark numbers to memorize.

12. Matching blood flow (Q, also called “perfusion” ) to ventilation (V) by pulmonary arterioles that constrict in response to low O2 and dilate in response to hi O2
(Note this response to O2 is opposite that of systemic arterioles!)
Thus, poorly ventilated regions of the lung will receive less blood flow.
So…. Q is “matched” to V, but not perfectly.

13. Carbon dioxide transport
carbaminohemoglobin
Chloride
Shift
CA = carbonic anhydrase
Hb is a Buffer
Carbon dioxide transport

14. Figure 13.31 Hb can bind O2, CO2, and H+
Increases in CO2 and H+ decrease the affinity of Hb for O2

15. Figure 13.27
CO2 and O2 bound to Hb do not contribute to partial pressure (no longer a dissolved gas!)

16. Oxygen exchange

17. Table 13.08

18. Steep
Flat