Respiratory System
If the partial pressure of oxygen in the alveolar air is 104 mm Hg, approximately what will be the concentration of dissolved oxygen in the blood leaving the pulmonary capillaries?
21 mm Hg
40 mm Hg
100 mm Hg
160 mm Hg
100 mm Hg
Oxygen will continue to diffuse from the alveoli across the respiratory membrane into the blood, while the concentration gradient exists. The gradient will exist until the plasma concentration reaches 104 mmHg. In reality blood travelling away from the alveoli will be at slightly less than 104 mmHg as some oxygen will have been used by the lung tissue.
100 mm Hg Oxygen will continue to diffuse from the alveoli across the respiratory membrane into the blood, while the concentration gradient exists. The gradient will exist until the plasma concentration reaches 104 mmHg. In reality blood travelling away from the alveoli will be at slightly less than 104 mmHg as some oxygen will have been used by the lung tissue.
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C. The tubes that enter a lobule
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Blood entering the capillaries of the alveoli has dissolved CO2 at 46 mm Hg and is separated from air in the alveoli, which contains CO2 at a partial pressure of 40 mm Hg, by the respiratory membrane. What will be the concentration of dissolved CO2 of the blood capillaries leaving the alveoli?
A. 40 mm Hg
B. 43 mm Hg
C. 46 mm Hg
D. 86 mm Hg
Mt. Everest “base camp” is located 5300 m above sea level. Here, the atmospheric pressure is 403 mmHg (rather than 760 mmHg at sea level), and the oxygen partial pressure in atmospheric air at this altitude is about 79 mmHg. What is the likely value for dissolved oxygen concentration in arterial blood for someone at base camp?
A. 149 mmHg
B. 104 mmHg
C. 79 mmHg
D. 50 mmHg
Which of the following buffer systems of the body is affected by the action of the lungs?
A. Protein
B. Monohydrogen phosphate/dihydrogen phosphate
C. Ammonia/ammonium
D. Carbonic acid/bicarbonate
Which molecule or ion dissolved in blood is able to stimulate the central chemoreceptors of the brain’s respiratory centre?
A. CO2
B. H3O+
C. O2
D. Ca2+
Which of the following lists the components of the respiratory membrane?
A. Alveolar epithelial cells, capillary endothelial cells and their basement membranes
B. Fluid and surfactant alveolar epithelial cells, capillary endothelial cells and their basement membranes
C. Visceral pleura, parietal pleura and serous fluid
D. Ciliated epithelial cells, mucus cells and secreted mucus
If the partial pressure of oxygen in the air contained in the alveoli of the lungs is 14 kPa, then the partial pressure of oxygen dissolved in the alveolar fluid will be:
A. Very close to 14 kPa
B. Significantly greater than 14 kPa
C. Significantly less than 14 kPa
D. Unable to be determined without the solubility coefficient of oxygen and the temperature of the alveolar fluid
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