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I have a very very limited understanding of biology because I never took anything other than a highschool class. Is hemoglobin critical just because of its abi

I have a very very limited understanding of biology because I never took anything other than a highschool class. Is hemoglobin critical just because of its ability to deliver oxygen to cells? If so could a synthetic replacement for hemoglobin be developed that could replace to function of hemoglobin in the human body? Or is this a issue of chemical structure where our body would reject non hemoglobin molecular structures attempting to deliver oxygen?

cjbgkagh 2y ago
[flagged]
georgyo 2y ago
Also not a biologist, but the the body actively rejects all things it considers foreign. Consider that we have A, B, O, and AB with both positive and negative variants as the most common blood types. Unless you're O+, you will reject the blood causing a massive immune response. Having the something that works like blood, the body won't reject, and has a shelf life longer than actual blood is hard.
- Kubuxu 2y ago
  AB+ is the universal recipient of red blood cells, O- is the universal donor. It is reverse for plasma. The blood rejection is reaction between blood plasma (with cells produced by your immune system) and red blood cells.
  - pacaro 2y ago
    And in addition, and TFA alludes to this, each time a person receives a transfusion there is a chance that their immune system will generate antibodies to it. That might not impact the transfusion at the time, but can make the recipient much harder to match for in the future. My partner has had severe anemia, and because of a prior transfusion went from being an easy match (A+) to a being a 1 in a thousand match. The last time she needed blood it took 12 hours to locate and transport suitable blood. If you read the literature on survival rates for people with very low hemoglobin level, it's all based on post operative recovery (or otherwise) of Jehovah Witnesses
utensil4778 2y ago
Mechanically, all hemoglobin does is take up an oxygen molecule when in an oxygen rich environment, and releases it in a CO2 rich environment. CO2 just dissolves into the bulk fluid of the blood and diffuses out in the lungs, it is not carried by hemoglobin. However, hemoglobin can bind to CO carbon monoxide, and it can't let go of it. The hemoglobin molecule is effectively dead and useless. If you had a molecule which functions in a similar way, it'd probably work in blood. The real trick is getting it to release the oxygen in the presence of CO2. Immune response is a different matter that I don't know enough about to weigh in on. I'd assume there's ways around it. Possibly immunosuppressor drugs for the (hopefully) short time you're on the synthetic blood.
dexwiz 2y ago
It needs to collect and release CO2 and O2 at the correct times and pressures. It needs to not be poisonous or toxic. It needs to not be quickly processed by the liver or kidneys, but processed enough that it doesn’t build up and become toxic. It needs to be evenly distributable via blood. It needs to not get into places where it shouldn’t be. It needs to not stick to things like artery walls. It needs to not cause an immune or inflammatory response. It needs to not cause you to clot or bleed out. And it needs to do all this and more in disparate parts of the body in varying chemical environments. The list of requirements is very long. Out body evolved alongside hemoglobin and finding a replacement that fits the bill perfectly is very difficult. Also hemoglobin appears in other places. Free oxygen is actually toxic in large amounts and will oxidize random things. Hemoglobin is used as an antioxidant to collect excess oxygen.
dbcooper 2y ago
Oxygen has very low solubility in water, which decreases with temperature. Haemoglobin binds iron atoms, which bind oxygen molecules, allowing storage of oxygen by the protein. IIRC, this increases the oxygen carrying capacity of blood approximately 60 to 70 times.

cjbgkagh 2y ago

[flagged]

georgyo 2y ago

Also not a biologist, but the the body actively rejects all things it considers foreign. Consider that we have A, B, O, and AB with both positive and negative variants as the most common blood types. Unless you're O+, you will reject the blood causing a massive immune response. Having the something that works like blood, the body won't reject, and has a shelf life longer than actual blood is hard.

Kubuxu 2y ago
AB+ is the universal recipient of red blood cells, O- is the universal donor. It is reverse for plasma. The blood rejection is reaction between blood plasma (with cells produced by your immune system) and red blood cells.
- pacaro 2y ago
  And in addition, and TFA alludes to this, each time a person receives a transfusion there is a chance that their immune system will generate antibodies to it. That might not impact the transfusion at the time, but can make the recipient much harder to match for in the future. My partner has had severe anemia, and because of a prior transfusion went from being an easy match (A+) to a being a 1 in a thousand match. The last time she needed blood it took 12 hours to locate and transport suitable blood. If you read the literature on survival rates for people with very low hemoglobin level, it's all based on post operative recovery (or otherwise) of Jehovah Witnesses

utensil4778 2y ago

Mechanically, all hemoglobin does is take up an oxygen molecule when in an oxygen rich environment, and releases it in a CO2 rich environment. CO2 just dissolves into the bulk fluid of the blood and diffuses out in the lungs, it is not carried by hemoglobin. However, hemoglobin can bind to CO carbon monoxide, and it can't let go of it. The hemoglobin molecule is effectively dead and useless. If you had a molecule which functions in a similar way, it'd probably work in blood. The real trick is getting it to release the oxygen in the presence of CO2. Immune response is a different matter that I don't know enough about to weigh in on. I'd assume there's ways around it. Possibly immunosuppressor drugs for the (hopefully) short time you're on the synthetic blood.

dexwiz 2y ago

It needs to collect and release CO2 and O2 at the correct times and pressures. It needs to not be poisonous or toxic. It needs to not be quickly processed by the liver or kidneys, but processed enough that it doesn’t build up and become toxic. It needs to be evenly distributable via blood. It needs to not get into places where it shouldn’t be. It needs to not stick to things like artery walls. It needs to not cause an immune or inflammatory response. It needs to not cause you to clot or bleed out. And it needs to do all this and more in disparate parts of the body in varying chemical environments. The list of requirements is very long. Out body evolved alongside hemoglobin and finding a replacement that fits the bill perfectly is very difficult. Also hemoglobin appears in other places. Free oxygen is actually toxic in large amounts and will oxidize random things. Hemoglobin is used as an antioxidant to collect excess oxygen.

dbcooper 2y ago

Oxygen has very low solubility in water, which decreases with temperature. Haemoglobin binds iron atoms, which bind oxygen molecules, allowing storage of oxygen by the protein. IIRC, this increases the oxygen carrying capacity of blood approximately 60 to 70 times.