| Question | Answer |
| Pulmonary Gas Exchange I | --oxygen enters the blood in the lungs and carbon dioxide leaves
--the movement of these gases is affected by partial pressure gradients and gas solubilities |
| Pulmonary Gas Exchange II | steep gradient of PO2 across the respiratory membrane (PO2 of venous blood in the pulmonary arteries is only 40 mm Hg compared to 104 mm Hg in the alveoli), as a result, oxygen diffuses rapidly from the alveoli into the lung capillaries |
| Pulmonary Gas Exchange III | partial pressure gradient for CO2 is much less steep (45 mm Hg in the lung capillary blood vs. 40 mm Hg in the alveoli), however, because CO2 is 20 times more soluble in plasma than oxygen is, it is exchanged at equal rates as oxygen. |
| Capillary Gas Exchange in the Body Tissues (Internal Respiration) | the partial pressure and diffusion gradients are reversed in the body tissues
due to their metabolic activities, cells constantly use oxygen and produce equal amounts of carbon dioxide |
| Capillary Gas Exchange II | PO2 in the tissues is always lower than in the syst arterial blood (40 mm Hg to 104 mm Hg, respectively), therefore, 02 rapidly diffuses from the blood into the tissues
- |
| Capillary Gas Exchange III | -CO2 moves in the opposite direction (from tissues into the blood), along its own partial pressure gradient
-venous blood draining the capillary beds of the tissues and returning to the heart has a PO2 of 40 mm Hg and a PCO2 of 45 mm Hg |