Red blood cells (RBCs), also known as red cells, haematodes, red blood corpuscles, erythrocytes or erythroid cells (from Greek erythros for "red" and kytos for "hollow vessel," with -cyte translated as "cell" in modern usage), have been the most typical type of blood cell and the vertebrate's main way to deliver oxygen to body tissues through blood supply through the circulatory system. RBCs absorb oxygen from the lungs or the gills of fish and discharge it into tissues while pumping via the capillaries of the body.
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Hemoglobin, an iron-containing bio-molecule which can bind oxygen and is responsible for the red colour of the cells and blood, is abundant in the cytoplasm of erythrocytes. These haemoglobin molecules are found in around 270 million human red blood cells. The cell membrane is made up of proteins and lipids, and it supplies qualities necessary for physiological cell function like deformability and stability when travelling through the circulatory system, particularly the capillary network.
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Human mature red blood cells are oval biconcave discs that are flexible. They lack a cell nucleus and also most organelles to allow for optimum haemoglobin storage; they could be thought of as haemoglobin sacks with a plasma membrane acting as the sack. In adults, around 2.4 million new erythrocytes are created every second. The cells form in the bone marrow and circulate in the body for roughly 100–120 days until being recycled by macrophages. It takes roughly 60 seconds for each circulation (one minute). 20–30 trillion red blood cells make up about 84 percent of the cells in the body of a human. Red blood cells make up over half of the blood volume (40 to 45 percent).
Erythropoiesis is the process by which human red blood cells evolve from committed stem cells to mature red blood cells in roughly 7 days. When fully grown, these cells can survive in the bloodstream for up to 120 days in a healthy person. They are taken out of circulation when they reach the end of their useful life. The lifespan of red blood cells is shortened in several chronic illnesses.
Creation - The process of producing new red blood cells, erythropoiesis, lasts roughly 7 days. Red blood cells were continuously created in the red bone marrow of big bones as a result of this process. (The liver is the primary location of red blood cell synthesis in the embryo.) The hormone erythropoietin (EPO), which is produced by the kidney, can boost output. Reticulocytes are growing cells that form just before and after leaving the bone marrow; they make up about 1% of circulating red blood cells.
Functional Lifetime - A red blood cell does have a functional lifetime of roughly 100–120 days, and during that time it is constantly pushed by blood flow push (in arteries), pull (in veins), or a mixture of the two as it squeezes via microvessels like capillaries. In addition, they are regenerated in the bone marrow.
Senescence - The plasma membrane of an ageing red blood cell changes, rendering it vulnerable to macrophage detection and eventual phagocytosis throughout the mononuclear phagocyte system (liver, spleen, and lymph nodes), eliminating old and faulty cells and purifying the blood. Eryptosis, or the programmed death of red blood cells, is the name given to this process.
This mechanism balances the overall circulating red blood cell count by occurring at the very same pace as erythropoiesis. Sepsis, malaria, haemolytic uremic syndrome, beta-thalassemia, sickle cell anaemia, phosphate depletion, glucose-6-phosphate dehydrogenase deficiency, iron insufficiency, and Wilson's disease all lead to an increase in eryptosis.
Disease - The following are examples of blood disorders that affect red blood cells:
Anemias (or anemias) are disorders in which the blood's oxygen transport capacity is reduced due to decreased red cell count or a defect in the red blood cells or haemoglobin.
The most prevalent anaemia is iron deficiency anaemia, that develops when the food intake or absorption of iron is inadequate, preventing the formation of haemoglobin, which contains iron.
Sickle-cell disease is a hereditary condition that causes faulty haemoglobin molecules to form. These become insoluble as they release their oxygen load within tissues, resulting in misshapen red blood cells. These sickle-shaped red cells seem to be less deformable and viscoelastic, causing blood vessel blockage, strokes, discomfort, and other tissue damage.
Thalassemia is a hereditary disorder that causes an improper ratio of haemoglobin components to be produced.
Pernicious anaemia is an autoimmune condition in which the body lacks intrinsic factor, which is necessary for food absorption of vitamin B12. Hemoglobin is produced with the help of vitamin B12.
The failure of the bone marrow to create blood cells causes aplastic anaemia.
The failure of the bone marrow to manufacture just red blood cells causes pure red cell aplasia.
Transfusion - A blood transfusion may include the administration of red blood cells. Blood might be supplied by someone else or preserved by the receiver at a previous time. Donated blood is frequently subjected to screening to verify that donors do not have risk factors for blood-borne infections or will not be harmed as a result of providing blood.
Hepatitis B, Hepatitis C, and HIV are all frequent or significant blood-borne infections that are usually collected and tested. To reduce the risk of an acute hemolytic transfusion reaction (A, B, AB, or O), the blood type (A, B, AB, or O) or the blood product is recognized and compared with the recipient's blood. This refers to the existence of antigens on the cell surface. After this, the blood is kept and then used within a short period of time. Blood could be supplied as a whole product or as packed red blood cells if the red blood cells are separated.
Tests - Red blood cells are used in a variety of blood tests. RBC count, hematocrit calculation, and erythrocyte sedimentation rate are among these tests. To prepare for a blood transfusion or an organ transplant, the blood type must be verified.