bio (1116) - MaB: haemoglobin

letsee.. a lot to talk about in today's post.

today's subject of discussion was haemoglobin, the substance within red blood cells that attracts oxygen and takes it to cells in the body.

haemoglobin is composed of haem (made of iron, thus is red) and globin, which is a helix of proteins that is folded around 5-7 times.

mr mahfouz explained that there is approx 2-3 million molecules of haemoglobin in a single RBC (red blood cell), and remember there are 4-7million RBCs in 1mL of blood, and on average 5L of blood in a person. so that's a crapload of haemoglobin, and considering they each fit 4 oxygen molecules, thats a lot of oxygen.

thing is the book said 200-300 million, i dunno where the error is there.. i have to clear that up tomorrow.

so. once again fouzeh described haemoglobin's oxygen capacity to be like car seats. 4 seats. and once one is fillled, all 4 must be filled immediately. so that haemoglobin carries either 4 or 0 oxygen molecules.

fouzeh used a brilliant analogy of the haemoglobin's ability to easily obtain oxygen from the alveoli as a "beautiful blonde girl". someone who can really easily attract/pick up a guy (oxygen) and a few minutes later.. just as easily dump him (somewhere in the cells hahaha)

fouzeh talked about something called partial pressure, which is basically air pressure. air pressure is measured in mmHg (mm of mercury) i dont know why.. i'll ask that tomorrow too. but it basically means, in 1cm^2 of land on the earth, all the way upwards 'til the end of the atmosphere, what is the concentration of air. it turns out to be 760mmHg. and approx 21% is oxygen, so we get something like 160.

we looked at a diagram to haev a look at the PO2 (P = partial pressure, O2 = oxygen) and PCO2. the oxygen moved around quite abit, i suppose tahts coz haemoglobin is made for carrying oxygen. the way it transports this is simple, it's all diffusion. oxygen moves from an area of high concentration (lungs) to areas of low concentration (blood vessels) to be carried around. when it eventually reaches capillaries (very narrow vessels, like 1 cell wide in diameter) oxygen is dumped in the cells and the liquid surrounding them.

around 98% of oxygen is carried around by blood cells, the other 2% is dissolved in the blood's plasma.

fouzeh used an example.

8 years ago when the socceroos were going to south america for the world cup, they were told that it wouldnt be good for them, coz they would be playing 1000m above sea level (where air pressure/concentration) is lower. so to fix that, they were sent there two weeks prior to the game, to adapt. so that their body could produce more blood cells, and wider vessels to fit them.

apparently mountain folk have wide vessels.

last thing, haemoglobin saturation. if there are 4 haemoglobin molecules, and 2 of them haev oxygen attached, it would be 50% saturation. etc