IV: Gas Transport- Alveolocapillary Membrane

Question 1

Oxygen and carbon dioxide are moved by ______ from one blood region to another.

Answer 1

convection

Question 2

Does oxygen move according to partial or total pressure gradients? What about air and blood?

Answer 2

oxygen (and carbon dioxide) moves down partial pressure gradients, while air and blood move down total pressure gradients

Question 3

Blood ______, while air _______.

Answer 3

circulates; reciprocates

Question 4

Where does gas exchange with alveolar air take place?

Answer 4

NOT along the larger extra-alveolar vessels, but ONLY along the alveolar capillaries. (the extra-alveolar vessels solely act as supply and return vessels–not exchange vessels)

Question 5

When we stop breathing, which is more of a problem– oxygen or carbon dioxide?

Answer 5

CO2 is the problem because it diffuses so slowly in air that it starts building up in the alveolar space (need to apply artificial ventilation)

Question 6

How soon does equilibration take place during transit of RBCs through pulmonary capillaries?

Answer 6

during the first third of the transit (0.25 s) - blood and alveolar gas only have 0.75 seconds to equilibrate due to fast transit time of RBCs across gas exchange zone of pulmonary capillaries.