The Student Room Group
Reply 1
Fetal HHb needs to have more affinity for O2 to deliver the already-low concentration of O2 in the placenta.

Bohr effect says, HHb saturation is affected by pH and O2 partial pressure.
Reply 2
Fetal haemoglobin has a higher affinity for o2 than the mothers haemoglobin so that the foetus can get more oxygen as it lives in a low oxygen environment - or something along those lines.

Bohr affect;
1. C02 is produced by the respiring tissues and diffuses into the red blood cell. Some c02 combines with haemoglobin to form carbaminohaemoglobin
2. Carbonic anhydrase an enzyme in red blood cells catalyses a reaction between the C02 and the H20. This produces carbonic acid
3. Carbonic acid disassociated to form H+ ions and HC03- ions. The H+ ions increase the acidity of the red blood cell
4. H+ ions combine with oxyhaemoglobin to give haemoglobonic acid (Hbb). As they combine the shape of the molecule changes which decreases its affinity for 02 and is released to the tissues (this is called the bohr affect)
5. HC03- begins to build up and diffuse out of the red blood cell, so this leaves inside of the membrane positively charged
6. CL- ions diffuse into the red blood cell from the plasma in order to balance the electrical change, this is known as the chloride shift

Thats basically it I think. Hope it helps.
Keith....perhaps you should pay attention in class....lol
Reply 4
HEY. THE TOPIC GOT ADDED. YAY. I've been trying for aggggees but it wouldn't load....

Thanks for your help guys. You are all the best.

And Priyanka1992, who are you? I'm not even in your class...so how do u know i don't pay attention?? :wink:.

I try to pay attention in class, but our biology teacher is wayyyy too buff and i spend most of my time drooling over her instead. There's nothing i can do about it. :biggrin:
Keith_Dave
Hey dudes,

I have a biology test tommorow and i am pretty sure that there will be some disocation curve questions which we will have to answer.

Can someone please explain to me why fetal haemoglobin is more saturated than human haemoglobin???

Also, can someone please explain the bohr effect as well?


Thanks.

funny that, we were doing the exact same thing you must be doing OCR
i think that foetal haemoglobin has a higher affinity for oxygen or something for better access to mothers blood or something
Reply 6
One of the reasons why this occurs is because fetal haemoglobin is less sensitive to a chemical known as 2,3-DPG; it is a product of RBC metabolism and is right-shifting.

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