Through what layers must the oxygen we breath pass before it actually meets its buddy the RBC?
Surfactant -> Type I epithelium -> Interstitial space -> Pulmonary capillary endothelium -> blood plasm -> RBC
If you flew to a planet where the atmospheric pressure was 100mmHg and the composition of oxygen in the air was 20%, how would oxygen diffusion take place at the alveoli?
If our arterial PO2 remained the same (40mmHg), it O2 would flow from the blood out to the air because the PO2 of the atmospheric air is 20mmHg (100*0.2) and the diffusion gradient in our lungs would essentially be reversed.
How does alveolar air differ from atmospheric air? What are the partial pressures of O2 and CO2 in the alveoli and in the pulmonary arteries?
Decreased O2 and increased CO2 due to diffusion gradient. Increased water vapor due to air moistening by air passages.
What factors affect the diffusion rate proportionally? Inversely? How do these factors change diffusion of CO2 and O2?
PROPORTIONALLY: solubility of the gas, difference in partial pressures between compartments, cross-sectional surface area of diffusion and temperature. INVERSELY: molecular weight of the gas and distance of diffusion. With all of these factors in consideration, the diffusion coefficient of CO2 is 20 where O2 is only 1.
What is the total surface area of the alveoli in the two lungs?
70-100 square meters
How does the anatomy of the alveoli optimize gas exchange?
Extensive surface area (millions of alveoli) and short diffusion distance (wall of capillaries surrounding each alveoli, with extremely thin respiratory membranes).
Why do you not see a decrease in oxygenation of RBCs during exercise?
O2 diffusion across the alveoli into the RBCs is rapid
What contributes to the binding curve seen in hemoglobin seen below?
Allosteric and operative binding. As oxygen binds to the Fe in one heme group, the other 3 heme groups increase in affinity for oxygen.
Which curve is hemoglobin and which is myoglobin?
The purple curve is myoglobin. It only has one heme binding site and thus a rapid increase in saturation when pO2 increases.
If arterial pressure is 94mmHg and interstitial pressure is 40mmHg. What percent of hemoglobins oxygen is being given up to the tissues? What would happen during exercise?
25% (97-72). During exercise, hemoglobin gives up more of its oxygen to the tissue and interstitial pO2 is dramatically decreased.
During exercise, your hemoglobin dissociation curve will shift which way and why?
It shifts to the right in order to cause increased O2 delivery to tissues. This is caused by increased H+, CO2, temperature and BPG (bisphosphoglycerate).
What drives oxygen out of hemoglobin and into peripheral cells that need it?
Flow down its pressure gradient.
Two patients come to see you, one is anemic and the other hypoxic from mountain climbing. What is one treatment you could prescribe to both patients that would help them out?
Increased cardiac output
Why does carbon monoxide poisoning occur?
CO has a higher binding affinity for O2, competitively inhibiting it. CO also increases binding affinity of hemoglobin for O2, decreasing release of O2 at tissues and shifting the Hgb/O2 dissociation curve to the left.