where does red blood cell production occur in adults
Red blood cell In humans, mature red blood cells are flexible and oval biconcave disks. They lack a cell nucleus and most organelles, in order to accommodate maximum space for hemoglobin; they can be viewed as sacks of hemoglobin, with a plasma membrane as the sack. Approximately 2.4 million new erythrocytes are produced per second in human adults.[2] The cells develop in the bone marrow and circulate for about 100â€“120 days in the body before their components are recycled by macrophages. Each circulation takes about 60 seconds (one minute).[3] Approximately a quarter of the cells in the human body are red blood cells.[4][5] Nearly half of the blood's volume (40% to 45%) is red blood cells.
Packed red blood cells Packed red blood cells, also known as red cell concentrate and packed cells, are red blood cells that have been separated for blood transfusion.[1] They are typically used in anemia that is either resulting in symptoms or when the hemoglobin is less than 70–80 g/L (7–8 g/dL).[1][2] One unit brings up hemoglobin levels by about 10 g/L (1 g/dL).[3] Repeated transfusions may be required in people receiving cancer chemotherapy or who have hemoglobin disorders.[1] Cross matching is typically required before the blood is given.[1] It is given by injection into a vein.[4]