The iron in hemoglobin must be in the ferrous (+2) state to bind oxygen. If the

Question

The iron in hemoglobin must be in the ferrous (+2) state to bind oxygen. If the iron of hemoglobin becomes oxidized to the ferric (+3) state, the corresponding hemoglobin, called methemoglobin, cannot bind oxygen. To maintain iron in the ferrous state, red blood cells contain a reducing system to convert any methemoglobin back to hemoglobin. Some variant forms of hemoblobin, such as hemoglobin M, cannot be reduced by that system. What would be the expected clinical presentation of a patient having HbM?

Explanation / Answer

the patients clinical presentation of having the methemoglobinemia ;

methemoglobenemia is a disorder charecterised by the higher levels of the methemoglobin where hemoglobin will b ein ferric state ,than the normal ferrous state . Ferric state of hemoglobin has decreased ability to bind to oxygen ,the ferrous ion has the increased ability for oxygen .The binding of oxygen to the methemoglobin will result in increased affinity of oxygen to three other heme sites within same tetrameric ring ,this leads to overall reducing ability of the oxygen to be relased to tissues by the RBC cells ,therefore oxygen hemoglobin dissociation curve is shifting to left

symptoms include ; hypoxia , headche ,fatigue , cynaosis .etc .severe methhemoglobin causes the seizures ,coma .

congential methemoglobin , may be due to deficiency of the enzyme diaphorose 1 {NADH methemoglobin reductase ] methhemoglobin levels rise ,the arterial blood turns brown , patients appear blue .heridiatry methemoglobin is caused by the recessive gene ,if only one parent is having the offspring will be normal heued , if boththe parents is having the offspring will be blue heued skin .

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