Red blood cell Red blood cell Red blood cells, also known as RBCs, red cells, red blood corpuscles, haematids, erythroid cells or erythrocytes (from Greek "erythros" for "red" and "kytos" for "hollow vessel", with "-cyte" translated as "cell" in modern usage), are the most common type of blood cell and the vertebrate's principal means of delivering oxygen (O) to the body tissues—via blood flow through the circulatory system. RBCs take up oxygen in the lungs, or gills of fish, and release it into tissues while squeezing through the body's capillaries. The cytoplasm of erythrocytes is rich in hemoglobin, an iron-containing biomolecule that can
Packed red blood cells a health system. In the United Kingdom they cost about 120 pounds per unit. A number of other versions also exist including whole blood, leukocyte reduced red blood cells, and washed red blood cells. More than 100 million units of blood are collected each year around the world, and about 50% of these are given to people in high income countries. In low-income countries, the majority of blood transfusions (up to 65%) are given to children under 5 years of age to treat severe childhood anemia. Another major use of blood in low income countries is to treat pregnancy-related complications.