Partial Pressure and Gas Diffusion — NEET Biology
✅ Asked in NEET 2021Pressure contributed by an individual gas in a mixture of gases is called partial pressure and is represented as pO₂ for oxygen and pCO₂ for carbon dioxide. Partial pressures of these two gases in the atmospheric air and the two sites of diffusion are given in Table 14.1 and in The data given in the table clearly indicates a concentration gradient for oxygen from alveoli to blood and blood to tissues. Similarly,
NTA tests your understanding of partial pressure gradients that drive gas exchange. Partial pressure (pO₂ and pCO₂) determines the direction and rate of gas diffusion across concentration gradients. Students commonly confuse partial pressure with total atmospheric pressure or forget that O₂ moves from alveoli to blood because pO₂ is higher in alveoli. The critical concept: gases always diffuse from higher to lower partial pressure. Remember the gradient sequence—alveoli (high pO₂) → blood (lower pO₂) → tissues (lowest pO₂). This principle explains why gases move in specific directions without any active transport, making it a fundamental mechanism NTA frequently tests.
This paragraph was tested 2 times in NEET.
What are the partial pressures (in mmHg) of O₂ and CO₂ in alveoli? NEET 2021
The partial pressure of oxygen in the alveoli of the lungs is [NEET Phase II – 2016]
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