Question

how we can breathe by taking oxygen why we cannot take another gas which is present in the atmosphere what is a reason that we only take oxygen and produce co2

Answer 1

the haemoglobin in our blood has affinity for Oxygen, mainly. So when we breathe in, Oxygen gets diffused in our blood through alveoli because the amount of oxygen in our blood is less than the amount present outside. when oxygen enters our blood, it is binded with haemoglobin. CO2 is a metabolic waste in our body, so when we breath out, the CO2 gets diffused out in the atmosphere, because the amount (or partial pressure) of CO2 is greater in our blood as compared to atmosphere.


We cannot take in other gases from atmosphere, like Nitrogen, because niteogen needs high pressure environment to dissolve, and tge pressure of our blood is not sufficient.


however, when deep sea divers swim extremely deep in the ocean/sea, the pressure increase and some amount of Nitrogen also enters their blood, which is dangerous.

Answer 2

The atmosphere contains several gasses. A fire burns due to an oxidation reaction, which required Oxygen. How does only Oxygen get separated here?

It doesn't! Oxygen is used up, and the rest just remains there.

A similar occurrence happens where breathing is concerned. When we inhale air, all the other gases present in it also enter our lungs. We have no selective mechanism to inhale only oxygen. In the terminal region of lungs, the alveoli, an exchange of gases takes place. The Haemoglobin in RBCs has an affinity for this oxygen present(Due to the iron contained in the Haemoglobin) in the inhaled air and it is immediately absorbed. The remaining gases are inert (with respect to the blood's constituents) which are sent out during exhalation.