Tamilnadu BoardEnglish MediumSTD 11Bio ZoologyRespiration3 Marks
Question
How does a gaseous exchange take place in the alveoli?
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Answer
The primary site for the exchange of gases in the alveoli. The uptake of 02 and the release of $CO _2$ occur between the blood and tissues by simple diffusion driven by partial pressure gradient of $O _2$ and $CO _2$. Partial pressure is the pressure contributed by an individual gas in a mixture of gases.It is represented as $pO _2$ for oxygen and $pCO _2$ for carbon- dioxide. Due to pressure gradients, $O _2$ from the alveoli enters the blood and reaches the tissues. $CO _2$ enters into the blood from the tissues and reaches alveoli for elimination. As the solubility of $CO _2$ is $20-25$ times higher than that of $O _2$, the partial pressure of $CO _2$ is much higher than that of $O _2$.
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