The oxygen dissociation curve taught me...

A good piece of information does not come free, and it does not come with a click or a button hit!

Today, after years, finally a very basic information sank into my mind!

Since I am a newly graduated physician, (actually since I am a physician at all), studying is an ongoing process. Being a doctor, means being a "professional student" :)

So being, the professional student, I got a chance to attend a lecture about Arterial Blood Gases, wherein, basics of Oxygen forms in the blood were reviewed.

So why am I mentioning this?! Because, this is a lesson I first learned back in school, when I was sitting for my IGCSE O'Level Biology. Then, I learned about the Oxygen Dissociation Curve, with the ever amazing "shift to the left" and "shift to the right" phenomenon! I had this taught on my mind: "this is too basic! Have I not passed this already???"

Maybe, it ain't time to jump into details, but for the record, and because I would love to articulate what I learned as well as explain Today's lesson, I would be just explaining in few words what this is all about. Oxygen can exist in chemical and physical forms. The physical form is the gaseous form. By chemical form, I am referring to the bonding of 4 Oxygen molecules (O₂₎ , by covalent bonds to the iron in hemoglobin. Each hemoglobin molecule has 4 binding sites, and a saturated hemoglobin is one where all the sites are occupied by O₂. Oxygen saturation is thus a measure of the amount of oxygen in the blood, bound to hemoglobin. This, amazingly depends to a number of factors, the top of which is the Partial Pressure of Oxygen, which varies greatly along the vessels and across different membranes. This is called, the oxygen cascade

It is this oxygen cascade that provides a wide scale of O₂ pressures on the x-axis of the O₂ saturation (dissociation) curve, while the O₂ saturation is on the y-axis.
I have always known how to read the curve; though I had a hidden gap in understanding the whole picture. As Dr. Heba Ismail, a remarkable anaesthetist lectured us Today, spoke of the oxygen cascade, something just lit inside my head: like a puzzle, with a missing piece, has a distorted picture; so was my understanding of this amazing phenomenon explained by this curve! As I understood Today for the first time about the cascade, the missing piece just fit in and after years finally the information sank in!

The cost of knowledge is big: one of its main currencies is time and persistence; and a thing called, you're never big enough to sit for a class of basics, even after gaining your degree! :)