From Wikipedia, the free encyclopedia
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Human red blood cells (6-8μm)
Red blood cells (also referred to as erythrocytes) are the most common type of blood cell and the vertebrateorganism's principal means of delivering oxygen (O2) to the body tissues via the blood flow through thecirculatory system. They take up oxygen in the lungs or gills and release it while squeezing through the body'scapillaries.
These cells' cytoplasm is rich in hemoglobin, an iron-containing biomolecule that can bind oxygen and is responsible for the blood's red color.
In humans, mature red blood cells are flexible biconcave disks that lack a cell nucleus and most organelles. 2.4 million new erythrocytes are produced per second.[1] The cells develop in the bone marrow and circulate for about 100–120 days in the body before their components are recycled by macrophages. Each circulation takes about 20 seconds. Approximately a quarter of the cells in the human body are red blood cells.[2][3]
Red blood cells are also known as RBCs, red blood corpuscles (an archaic term), haematids, erythroid cells or erythrocytes
A typical human erythrocyte has a disk diameter of 6–8 µm and a thickness of 2 µm, being much smaller than most other human cells. These cells have a volume of about 90 fL with a surface of about 136 μm2, and can swell up to a sphere shape containing 150 fL, without membrane distension.
Adult humans have roughly 2–3 × 1013 (20-30 trillion) red blood cells at any given time, comprising approximately one quarter of the total human body cell number (women have about 4 to 5 million erythrocytes per microliter (cubic millimeter) of blood and men about 5 to 6 million; people living at high altitudes with low oxygen tension will have more). Red blood cells are thus much more common than the other blood particles: there are about 4,000–11,000 white blood cells and about 150,000–400,000 platelets in each microliter of human blood.
Human red blood cells take on average