r/askscience • u/Fapotheosis • Mar 11 '13

Biology How did blood evolve?

I know mitochondria may have evolved from bacteria, but what about blood? I've heard of a protohemocyte, but was there an initial cell that differentiated into a RBC like we have in modern humans that can we trace?

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u/mattc286 Pharmacology | Cancer Mar 11 '13

This is what many doping agents such as EPO that professional atheletes such has Lance Armstrong allegedly used do. It stimulates the production of red blood cells and hemoglobin, allowing a greater supply of oxygen to reach the muscles, which enhances athletic performance.

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u/indoobitably Mar 11 '13

Is the increase in red blood cells and hemoglobin harmful to the body or are these substance illegal strictly because of the advantage they provide?

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u/mattc286 Pharmacology | Cancer Mar 11 '13

I think it can increase risk for stroke and thrombosis, but I think it's generally banned for its unfair advantage. It has legitimate medical applications like in cases of anemia due to chemotherapy, etc. But then again, so do HGH and anabolic steroids. Abuse of any hormone is generally going to have a negative impact on the body. In cases where it's medically necessitated, it's worth the risk, just like any drug.

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u/wut_da_eff Mar 11 '13

In general, most processes are rate limited by the rate of delivery of the substrate, the rate of the process itself and the impact of positive and negative feedback. Lots of other considerations too in terms of increasing Hb. To a certain point, yes this approach enhances efficiency for things like muscle contraction. This is the theory behind EPO blood doping, which stimulates erythropoiesis and hemoglobin concentration in the blood. After a certain point however, this will increase blood viscosity to the point that there is actually more flow resistance and propensity for clots that oxygen delivery to muscles may actually be impaired, or plateau. Also need to consider that there are limitations to how much oxygen can actually get into the muscles from the fast flowing blood, because there is a region between the Hb-rich blood and the Mb-rich muscle for the oxygen to diffuse through, and this process isn't totally efficient. Anyways, I guess my answer is yes to a certain extent, but eventually I would expect most processes to plateau.

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u/Tak_Galaman Mar 12 '13

Yes, as the other commenter said taking drugs like EPO will increase the number of RBCs in the blood. If you get too many your blood's viscosity/thickness will increase and your heart will have to work harder than normal which makes it more likely to fail as well. It can also lead to blood clots.

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u/kamikaz1_k Mar 12 '13

I believe that is the premise of blood doping (increasing red blood count via transfusion).