Carbon dioxide is transported in blood by all the following mechanisms except:
1. bound to the protein portion of hemoglobin
2. bound to the iron atoms of hemoglobin
3. dissolved in plasma
4. as bicarbonate
The conversion of carbon dioxide into carbonic acid in the red blood cells is catalyzed by the enzyme:
1. hemoglobin | 2. carbonic anhydrase |
3. carbonic oxidoreductase | 4. carbonic transferase |
The efficiency of a respiratory system is enhanced by all the following except:
1. | increasing the surface area available for diffusion of gases |
2. | decreasing the distance over which the gases must diffuse |
3. | increasing the concentration differences of gases inside and outside the system |
4. | drying the system out so the gases do not have to diffuse through water |
Exchange of gases occurs across the respiratory membrane. Which of the following would increase the rate of diffusion of a gas across the respiratory membrane?
1. | respiratory membrane becomes thicker. |
2. | surface area of the respiratory membrane decreases. |
3. | partial pressure difference of the gas across the respiratory membrane increases. |
4. | diffusion coefficient of the gas decreases. |
In inspiration during pulmonary ventilation the correct order of the given events is:
a. air flows into the lungs
b. alveolar volume increases
c. thoracic volume increases
d. pleural pressure decreases
e. alveolar pressure decreases
1. | a, b, c, d, e | 2. | b, e, a, c, d |
3. | c, d, b, e, a | 4. | d, e, b, a, c |
When compared with carbon dioxide, the partial pressure of oxygen in the air and its solubility in water is respectively:
1. lower, lower | 2. lower, higher |
3. greater, lower | 4. greater, higher |
Name the cavities in which the lungs are located:
1. pleural and abdominal cavities.
2. pericardial and thoracic cavities.
3. pleural and thoracic cavities.
4. pleural and pericardial cavities.
What is the partial pressure of oxygen and carbon dioxide respectively in the venous blood leaving the tissues [in mm of Hg]?
1. 104, 40 | 2. 95, 40 |
3. 40, 45 | 4. 20, 46 |
A minimal amount of pleural fluid present in the pleural cavity:
1. | provides a medium for the exchange of respiratory gases |
2. | reduces friction between the visceral and parietal pleurae |
3. | provides lubrication for movements of the diaphragm |
4. | permits the exchange of electrolytes during respiration |
When the diaphragm or external intercostal muscles contract, intrapulmonary pressure should
1. | increase | 2. | decrease |
3. | remain constant | 4. | equal atmospheric pressure |