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Red Blood Cells Metabolism

Essay Presentation of Erythrocyte (RBC) Anaerobic Pathways / Life Cycle / Life Span for Biology Medical Students 

METABOLISM OF RBCs 

Because of absence of such structu­res in the mature erythrocyte, like mitochondria, ribosome, rough endoplasmic reticulum, nucleus etc., many metabolic processes are absent. Thus, tricarboxylic acid cycle of Krebs is absent in the RBC and generation of AIP is poor.

Nevertheless, glucose is metabolized within the RBC and energy in the form of ATP are present. Metabolism in the ROC is needed for the following reasons :


(i) For maintaining the sodium potassium pump. Like all normal cells the erythrocyte has to pump out sodium to the ECF -and pump in K +from ECF, a process which requires energy.

Further, it is also known that lack of energy in the RBCs cause them to become rigid, fragile and spheroidal in shape, all leading to their lysis as they pass through the spleen.


(ii) The iron of the Hb, even after taking up the oxygen, remains in the ferrous state. If it is converted into ferric state, an abnormality, called methemoglobinemia results. Again, the exposure to oxygen, which an erythrocyte is al­ways having, may damage the Hb.

To prevent these above mentioned oxidative injuries (ie, methemoglobinemia, injury to Hb, rigidity of the RBC mem­brane, etc), various enzymes and reducing agents must be present in the RBC. The enzyme methemoglobin reductase to­gether with NADH prevents the iron to become ferric iron, whereas glutathione (GSH) which is a strongly reducing agent prevents damage of the Hb. To keep glutathione in reduced state, the activity of an enzyme, glucose-6-phosphate dehydrogenase (G-6PD), which is normally found in RBC, is necessary. In an inborn error of metabolism, G-6-PD deficiency, (which is sex linked) develops; therefore, the RBCs become susceptible to the damages due to oxidation. These people become especially vulnerable to oxidative damage after taking some types of antimalarial drugs. The symptoms include hemolysis, jaundice and anemia. These people are, however, somewhat immune against malaria.

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