An Attempt at a Formal Newspaper Artical

I immensely enjoy reading the Hindu science columns. They're so interesting!! They've got all the latest research, and I read everything, whether I understand it or not!! There's this one side column where anyone can ask questions and anyone can answer. The best questions and answers get published. It was last week, right after I finished my biology syllabus, that I thought I'd attempt to answer one of these questions. It took me about 2 hours to do that, including research and reading.

I thoroughly enjoyed writing this!! I hope you guys enjoy reading it!!

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The atmosphere contains several gasses. A person inhales that combination of gasses, but how is the oxygen differentiated from that in our respiratory system?

The earth’s lower atmosphere is composed of 78% nitrogen gas (N₂) and 21% oxygen (O₂). The remaining 1% is composed of argon (Ar) and carbon dioxide (CO₂) among several other minutely present gasses. The air we breathe in contains all these gasses, however, it is only oxygen that gets absorbed into our blood.

The air we breathe travels down our trachea, through our bronchi and into the bronchioles, eventually ending up at the alveoli. The alveoli are air sacks with a membrane as thick as 1 cell. Capillaries coming from the pulmonary artery wrap around these alveoli, and the air diffuses across the alveolar membrane into the capillaries.

The pulmonary artery coming from the heart contains deoxygenated blood. This deoxygenated blood has a low concentration of oxygen and a high concentration of carbon dioxide. At the alveolar membrane, CO₂ diffuses out of the capillaries down its concentration gradient (The CO₂ concentration in an alveolus in much lower than the concentration of CO₂ in the plasma of deoxygenated blood).

Nitrogen does not diffuse into the blood as the blood’s capacity to carry nitrogen is very low. The blood does contain N₂, but the concentration of it is always at a constant. This is because cells neither use nitrogen from the blood, nor do they excrete nitrogen into the blood.

The concentration of oxygen in the blood plasma is always low, regardless of whether it is oxygenated or deoxygenated. The reason for this is that the oxygen is always carried in Red Blood Cells (RBCs) and very seldom carried in the blood plasma itself. Each RBC contains millions of hemoglobin proteins, and each hemoglobin protein has the capacity to carry 4 oxygen molecules. All the O₂ in the blood plasma is sucked up by the RBCs, which is why the concentration of O₂ in the blood plasma is always low. As the oxygen concentration is greater in the air than that in the capillaries, oxygen diffuses across the alveolar membrane into the capillaries down its concentration gradient.

This is how oxygen is differentiated in the blood. 

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The writer is Rashmi Raju.

1208, Platinum, PBEL City,

APPA Junction, Hyderabad. 500008.