Search results
Results from the WOW.Com Content Network
The partial pressure of oxygen (pO 2) in the pulmonary alveoli is required to calculate both the alveolar-arterial gradient of oxygen and the amount of right-to-left cardiac shunt, which are both clinically useful quantities. However, it is not practical to take a sample of gas from the alveoli in order to directly measure the partial pressure ...
The alveolar oxygen partial pressure is lower than the atmospheric O 2 partial pressure for two reasons. Firstly, as the air enters the lungs, it is humidified by the upper airway and thus the partial pressure of water vapour (47 mmHg) reduces the oxygen partial pressure to about 150 mmHg.
Because A–a gradient is approximated as: (150 − 5/4(PCO 2)) – PaO 2 at sea level and on room air (0.21x(760-47) = 149.7 mmHg for the alveolar oxygen partial pressure, after accounting for the water vapor), the direct mathematical cause of a large value is that the blood has a low PaO 2, a low PaCO 2, or both.
The partial pressure gradient, also known as the concentration gradient, can be used as a model for the driving mechanism of diffusion. The partial pressure gradient is the rate of variation of partial pressure (or more accurately, the concentration) of the solute (dissolved gas) from one point to another in the solvent.
is the partial pressure of oxygen in the systemic veins (where it can actually be measured). Thus, the higher the diffusing capacity , the more gas will be transferred into the lung per unit time for a given gradient in partial pressure (or concentration) of the gas. Since it can be possible to know the alveolar oxygen concentration and the ...
The atmospheric pressure is roughly equal to the sum of partial pressures of constituent gases – oxygen, nitrogen, argon, water vapor, carbon dioxide, etc.. In a mixture of gases, each constituent gas has a partial pressure which is the notional pressure of that constituent gas as if it alone occupied the entire volume of the original mixture at the same temperature. [1]
Carbon dioxide removal in the alveoli depends on the partial pressure gradient for carbon dioxide diffusion between blood and the alveolar gas. This gradient is maintained by flushing carbon dioxide out of the alveoli during breathing, which depends on replacing air in the alveoli with more carbon dioxide by air with less carbon dioxide.
The alveolar oxygen is transferred to hemoglobin, a carrier protein inside red blood cells, with an efficiency that decreases with the partial pressure of oxygen in the air. Altitude. The external partial pressure of oxygen decreases with altitude, for example in areas of high altitude or when flying.