Red blood cells-RBCs or Erythrocytes

Red blood cells-RBCs or Erythrocytes

     These are the cells in small circular disc shape which are biconcave on the both sides. They are thick on the edge and thin in the middle. There is no nucleus in them but there is hemoglobin. About half volume of human blood is made of these red blood cells. They are present 4-6 million per cubic millimeter in the blood. Their diameter is about 7 micrometer and thickness is 2 micrometer. Single red cell appears light yellow colored when it is observed by a microscope. Normally, they are in group one above another in a long line close by to each other. They appear red in color if they are stayed in group. The blood is red because of this reason. There is a transparent membrane on the upper portion of the red blood cells which are flexible and colorless.   

     Proteins are needed for the red blood cells for its cells which are got from the amino acids. These cells need irons too and this is the reason that some quantity of iron should be present in the balanced diet. Women need much quantity of iron too.  

     Red blood cells originate in the bone marrow especially small, flat and irregular bones, in the cancellous tissue of the ends of long bones and in the shafts of ribs and in the marrow of sternum.

     Red blood cells undergo several phases of development in the bone marrow.  In the first phase, they are mega blast and there is nucleus in it too. In the second phase, they are normoblast and there is hemoglobin and nucleus. Thereafter, the nucleus gets dissolved by destroying and formations like thin thread are left in the cytoplasm. In this phase, cells are called reticulocytes. Finally, formations like threads come to an end and fully developed red blood cells or mature erythrocyte reach into the blood circulation and circulate all over the body.  

     The life period of red blood cells is about 120 days and that they get destroyed. They are imbibed in the reticuloendothelial system especially in the spleen and liver. Here hemoglobin reaches into liver by breaking into its different parts. Globin is used like protein in tissues by breaking into amino acids or is excreted with urine by breaking very much later on. The haem gets divided into two parts again first one is iron which gets gathered and then it is used in building new red blood cells and the second is pigment which gets changed into the bile pigments by the liver and is excreted with stool. The process of building and destroying remain continue with same rate and thus their counting remains fixed.