Information AboutRed Blood Cell |
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Red blood cells are the most common type of Blood Cell and the Vertebrate Body 's principal means of delivering Oxygen from the Lung s or Gill s to body tissues via the Blood . Red blood cells are also known as RBCs, '''haematids''', or '''erythrocytes''' (from Greek ''erythros'' for "red" and ''kytos'' for "hollow", with ''cyte'' nowadays translated as "cell"). A '''schistocyte''' is a red blood cell undergoing fragmentation, or a fragmented part of a red blood cell. VERTEBRATE ERYTHROCYTES , Thrombocyte , Leukocyte .]] Erythrocytes consist mainly of Hemoglobin , a complex Molecule containing Heme groups whose Iron atoms temporarily link to oxygen molecules in the lungs or gills and release them throughout the body. Oxygen can easily Diffuse through the red blood cell's Cell Membrane . Hemoglobin also carries some of the waste product Carbon Dioxide back from the tissues. (In humans, less than 2% of the total oxygen, and most of the carbon dioxide, is held in solution in the Blood Plasma ). A related compound, Myoglobin , acts to store oxygen in Muscle cells. The color of erythrocytes is due to the heme group of hemoglobin. The takes advantage of this color change to directly measure the Arterial blood Oxygen Saturation using Colorimetric techniques. The sequestration of oxygen-carrying proteins inside cells (rather than having them dissolved in body fluid) was an important step in the Evolution of Vertebrates ; it allows for less Viscous blood and higher concentrations of oxygen. MAMMALIAN ERYTHROCYTES Erythrocytes in s including their Mitochondria and produce energy by Fermentation , via Glycolysis of Glucose followed by Lactic Acid production. Furthermore, red cells do not have an Insulin Receptor and thus glucose uptake is not regulated by Insulin . As a result of the lack of nucleus and organelles, the cells cannot produce new structural or repair proteins or Enzyme s and their lifespan is limited. Mammalian erythrocytes are , where they release their oxygen load. Erythrocytes are circular, except in the Camel family Camelidae , where they are oval. In large blood vessels, red blood cells sometimes occur as a stack, flat side next to flat side. This is known as ''rouleaux formation'', and it occurs more often if the levels of certain serum proteins are elevated, as for instance during Inflammation . The Spleen acts as a reservoir of red blood cells, but this effect is somewhat limited in humans. In some other mammals such as Dog s and Horse s, the spleen sequesters large numbers of red blood cells which are dumped into the blood during times of exertion stress, yielding a higher oxygen transport capacity. HUMAN ERYTHROCYTES The diameter of a typical human erythrocyte disk is 6–8 µm , much smaller than most other Human Cells . A typical erythrocyte contains about 270 million hemoglobin molecules, with each carrying four heme groups. Adult humans have roughly and about 150,000–400,000 Platelet s in each microliter of human blood. The red blood cells store collectively about 3.5 grams of Iron , more than five times the iron stored by all the other tissues combined. Life cycle The process by which red blood cells are produced is called Erythropoiesis . Erythrocytes are continuously being produced in the red Bone Marrow of large bones, at a rate of about 2 million per second. (In the Embryo , the Liver is the main site of red blood cell production.) The production can be stimulated by the Hormone Erythropoietin (EPO), synthesised by the kidney; which is used for Doping In Sports . Just before and after leaving the bone marrow, they are known as Reticulocyte s which comprise about 1% of circulating red blood cells. Erythrocytes develop from committed stem cells through reticulocytes to mature erythrocytes in about 7 days and live a total of about 120 days. The erythrocyte undergoes changes in its plasma membrane making it susceptible to recognition and subsequent phagocytosis in the spleen, liver and bone marrow. Much of the important breakdown products are recirculated in the body. The heme constituent of hemoglobin are broken down into Fe3+ and biliverdin. The biliverdin is reduced to bilirubin, which is released into the plasma and recirculated to the liver bound to albumin. The iron is released into the plasma to be recirculated by a carrier protein called transferrin. Almost all old erythrocytes are removed from the circulation before they are old enough to hemolyze. Hemolyzed hemoglobin is bound to a protein in plasma called haptoglobin which is not excreted by the kidney. Surface proteins There are two main types of Protein s on the surface:
The Blood Type s of humans are due to variations in surface Glycoprotein s of erythrocytes. Separation and blood doping Red blood cells can be separated from which is not equipped to deal with blood of the resulting higher Viscosity . DISEASES AND DIAGNOSTIC TOOLS , red blood cells alter shape and threaten to damage internal organs.]] Blood Diseases involving the red blood cells include:
Several Blood Test s involve red blood cells, including the ''RBC count'' (the number of red blood cells per volume of blood) and the Hematocrit (percentage of blood volume occupied by red blood cells). The Blood Type needs to be determined to prepare for a Blood Transfusion or an Organ Transplantation . HISTORY In 1658 , the Dutch biologist Jan Swammerdam was the first to describe red blood cells. He had used an early Microscope . REFERENCES EXTERNAL LINKS
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