Why is a mature rbc biconcave

Enucleation involves dramatic chromatin condensation and establishment of the nuclear polarity, which is driven by a rearrangement of actin cytoskeleton and the clathrin-dependent generation of vacuoles at the nuclear-cytoplasmic junction. This process is favored by interaction between the erythroblasts and macrophages at the erythroblastic island.

Mitochondria are eliminated by mitophagy. Human erythrocytes or red blood cells RBCs are the primary cellular component of blood. They are involved in oxygen transport through the body and have features that distinguish them from every other type of human cell. Adult humans have roughly trillion RBCs at any given time, comprising approximately one quarter of the total number of human cells. RBCs are disc-shaped with a flatter, concave center.

This biconcave shape allows the cells to flow smoothly through the narrowest blood vessels. Gas exchange with tissues occurs in capillaries, tiny blood vessels that are only as wide as one cell. Many RBCs are wider than capillaries, but their shape provides the needed flexibility to squeeze through. Carayon, K. Proteolipidic composition of exosomes changes during reticulocyte maturation. Chan, E. Chen, Z. Autophagy 13, — Da Costa, L.

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Erythroblast enucleation is a dynein-dependent process. Koury, S. Cytoskeletal distribution and function during the maturation and enucleation of 13 mammalian erythroblasts. Koury, M. In vitro maturation of nascent reticulocytes to erythrocytes. Each chain has a heme group that contains an iron atom. Oxygen can bind to these iron atoms, which means that one molecule of hemoglobin can carry four oxygen molecules.

In the lungs, the hemoglobin in the red blood cells picks up oxygen. However, hemoglobin does not carry all the carbon dioxide in the blood back to the lungs—the blood can also transport CO2 as a dissolved gas or as bicarbonate HCO3. Like red blood cells, platelets are derived from myeloid stem cells. Some of these stem cells develop into megakaryoblasts, which give rise to cells called megakaryocytes in the bone marrow.

After a megakaryocyte has matured, pieces of its cytoplasm break away into cell fragments called platelets. A single megakaryocyte can produce — platelets. However, they do contain numerous granules or vesicles.

The hormone thrombopoietin, produced by the liver and kidneys, regulates the production of megakaryocytes and platelets. Platelets have different appearances in their inactivated and activated states.

When inactivated , platelets are irregularly shaped discs. Activated platelets are spherical, with protrusions that allow them to stick to wound tissue and to other platelets to form a plug at the site of a blood vessel tear.