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Red Blood Cells Life Span

Erythrocyte (RBC) Normal Short Expectancy Life cycle & its determination around the body Notes for Medical Biology students

LIFESPAN AND FATE OF RED BLOOD CELLS

Average lifespan of red blood cell is about 120 days. The senile red blood cells are destroyed in reticuloendothelial system. When the cells become older (120 days), the cell membrane becomes more and more fragile. The diameter of the capillaries is less or equal to that of red blood cell. The younger red blood cells can pass through the capillaries easily. However, because of the fragile nature, the older cells are destroyed while trying to squeeze through the capillaries. The destruction occurs mostly in the capillaries of spleen because the spleenic capillaries have a thin lumen. So, the spleen is usually called graveyard of red blood cells.

The destroyed red blood cells are fragmented. From the fragmented parts, the hemoglobin is released. The iron and globin parts of the hemoglobin are separated with the production of bilirubin. Iron combines with the protein-apoferritin to form ferritin, which is stored in body. Globin also enters the protein depot. The bilirubin is excreted by liver through bile.

Daily 10% red blood cells, which are senile, get destroyed in normal young healthy adults. This causes release of about 0.6 g% of hemoglobin into the plasma. From this 0.9 to 1.5 mg% bilirubin is formed.

DETERMINATION OF LIFESPAN OF RED BLOOD CELL

The lifespan of the red blood cell is determined by radioisotope method. The red blood cells are tagged with radioactive substances like radioactive iron or radioactive chromium. The life of red blood cell is determined by studying the rate of loss of radioactive cells from circulation.

Download Notes on Red Blood Cells Life Cycle

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