Why does the blood take oxygen from the air and no other gases??

Question

Why does the blood (haemoglobin) take oxygen from the air and no other gases?? If the property of haemoglobin is taking the gas which is more in the atmosphere then it should take nitrogen which is the largest quantity of gas found on earth then why does it take oxygen???

Answer 1

The blood takes in oxygen, because the haemoglobin has the chemical property of temporarily combining with oxygen. It does not have the chemical property of combining with nitrogen. It DOES have the chemical property of combining with Carbon Monoxide, which is what makes CO such a deadly poison to us. The CO gets in our bloodstreams, and we cannot take in the oxygen that we need.

29 JAN 07, 1822 hrs, GMT.

Answer 2

Thats a very good question that you ask. And there is a pretty clear answer to it. First of all, the only gases that are found near the surface of the earth are O2 and N2, and are at a mole fraction of 0.21 and 0.79 respectively. So if barometric pressure on the surface of the earth is 760 mmHg, then the partial pressures are represented by F * Pb (mole fraction times barometric pressure), and that comes out to about 160 and 600. However, this is changed in our bodies, where the respiratory tract ADDS vapor to the mix about 47 mmHg. That means that the total pressure of O2+N2 is now 760-47 = 713 INSIDE our respiratory tract. So the partial pressures of O2 and N2 inside our lung becomes 150 and 563, and water vapor is 47.

Great, I didn't answer your question yet, but I was just showing you how we figure out what species are in the lung. Keep in mind that the blood in capillaries gets exposed to this air across the alveolar membranes. But also keep in mind that gases are NOT VERY SOLUBLE in plasma. In fact, theyre almost insoluble to the point where no O2, N2, or H2O are crossing over the membrane and dissolving in the plasma. But if thats the case, how are we able to get oxygen to our tissues?

I'm sure you've heard of hemoglobin!!! Hemoglobin is the protein that binds, carries, and releases O2 to tissues in our circulation. Hemoglobin is able to take O2 out of the air in the alveolar spaces, and bind it, and transport it.

So how then is CO2 transported??? Red blood cells have an enzyme that converts CO2 that is produced in all cells as a product of catabolism into H2CO3, which dissociates into H+ and HCO3-. Both of these particles are indeed soluble in plasma! It is then converted back into CO2 near the lung and expired.

Answer 3

Haemoglobin transports oxygen and carbon di oxide with a chemical natured temporary bond. Releses oxygen at certain pressures and picks up CO2 at some other pressure. It is not carry it as physical means

Answer 4

The lungs seperate out one oxygen atom and expel everything else.

However they will absorb other gases as well, which is why keeping industry from polluting the atmosphere is so important.

Answer 5

Hemoglobin will take other kinds of gasses as well. Carbon monoxide poisoning is a good example of this.