I just read about diffusion today and I want to know how does a cell(plasma membrane to be more specific)know if O2 is being passing through it or CO2?
In: Biology
There is no active process involved. None of the cells “know” about O2 and CO2. The way it works is this – the mitochondria consumes nutrients and O2 to produce energy (and CO2 as a waste product). That causes the concentration of O2 in the proximity to drop and the CO2 concentration to rise. Then it’s all about the chemical process of diffusion – particles tend to move from an area of higher concentration to an area of lower concentration. In blood, there’s higher O2 concentration than in the proximity of the mitochondria, therefore O2 moves from the blood to the mitochondria. The reverse goes for CO2. In the lungs the situation is opposite – in the alveoli there’s higher concentration of O2 than in the blood and lower CO2 concentration.
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