Metabolism in erythrocytes

1) erythrocytes haven’t got mitochondrions, therefore anaerobic glycolysis is a main pathway of formation of ATP

2) erythrocytes haven’t got nucleus, therefore they don’t synthesize proteins or nucleic acids. These compounds are stored in period of maturation of erythrocytes in bone marrow

3) erythrocytes don’t synthesize glycogen and FFA. They get them during formation in bone marrow

4) glucose enters the erythrocytes independently on insulin

5) the extent of pentose’s cycle in erythrocytes is high and NADPH2 are used for action of MtHb-reductase and NADPH-oxydase of erythrocytes

6) MtHb-reductase reduces MtHb

7) During glycolysis 2,3diphosphoglycerate is formed which is used for deoxygenation

Hemoglobin participates in transfer of oxygen and carbon dioxide.

The transfer of oxygen is named as oxygenation. This process occurs in lungs:

Hb + O2 à HbO2 and requires some conditions: 1) high pressure of oxygen; 2) low pressure of carbon dioxide; 3) lower temperature than in tissues; 4) higher pH than in tissues.

So, hemoglobin transfers oxygen from lungs to tissues.

In tissues deoxygenation occurs: HbO2 à Hb + O2. This process occurs in conditions which are: 1) high pressure of carbon dioxide; 2) low pressure of oxygen; 3) higher temperature than in lungs; 4) more acidic pH.

The transfer of carbon dioxide occurs by 2 pathways: 1-st is direct one; 2-nd is indirect one)

(should be learned by reaction)

Direct pathway of transfer of carbon dioxide (15-20%) hemoglobin directly interacts with carbon dioxide yielding carbhemoglobin. This process occurs in tissues (venous blood). Carbhemoglobin is saturated by oxygen in lungs, carbon dioxide is released and eliminated from the body.

Indirect pathway of transfer of carbon dioxide (80-85%). This pathway occurs due to the presence of hemoglobin buffer. There are 2 types of hemoglobin buffer: HHb/KHb (in venous blood) and HHbO2/KHbO2 (in arterial blood). Firstly hemoglobin buffer of venous blood interacts with carbon dioxide in the kind of carbonic acid. This acid binds KHb, giving KHCO3 and HHb. KHCO3 interacts with HHbO2 in lungs yielding H2CO3 and KHbO2. Carbonic acid breaks up to CO2 and H2O. CO2 is eliminated from the body.

<== попередня сторінка	\|	наступна сторінка ==>
Biochemistry of erythrocytes	\|	The physiological and pathological derivatives of hemoglobin and their spectra of taking up

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