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Red blood cell concentrates, also known as red cell concentrates or packed red blood cells, are red blood cells that have been separated for blood transfusion. [1] A red blood cell concentrate typically has a haematocrit of 0.50 – 0.70 L/L and a volume between 250 and 320 mL.
They are responsible for the active transport of calcium out of the cell for the maintenance of the steep Ca 2+ electrochemical gradient across the cell membrane. Calcium pumps play a crucial role in proper cell signalling by keeping the intracellular calcium concentration roughly 10,000 times lower than the extracellular concentration. [1]
Calcium tends to have a slightly lower affinity for PMCA pumps than for SERCA pumps. [9] It is thought that the PMCA pump has 10 segments that cross the plasma membrane, with both C and N termini on the inside of the cell. [2] At the C terminus, there is a long "tail" of between 70 and 200 amino acids in length. [2]
Rendered image of the Ca 2+ pump. Plasma membrane Ca 2+ ATPase (PMCA) is a transport protein in the plasma membrane of cells that serves to remove calcium (Ca 2+) from the cell. It is vital for regulating the amount of Ca 2+ within cells. [3] In fact, the PMCA is involved in removing Ca 2+ from all eukaryotic cells. [4]
The formed elements are the two types of blood cell or corpuscle – the red blood cells, (erythrocytes) and white blood cells (leukocytes), and the cell fragments called platelets [12] that are involved in clotting. By volume, the red blood cells constitute about 45% of whole blood, the plasma about 54.3%, and white cells about 0.7%.
The US Institute of Medicine (IOM) established Recommended Dietary Allowances (RDAs) for calcium in 1997 and updated those values in 2011. [6] See table. The European Food Safety Authority (EFSA) uses the term Population Reference Intake (PRIs) instead of RDAs and sets slightly different numbers: ages 4–10 800 mg, ages 11–17 1150 mg, ages 18–24 1000 mg, and >25 years 950 mg. [10]
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 per microliter. Human red blood cells take on average 60 seconds to complete one cycle of circulation. [5] [9] [22]
Blood is a complex liquid. Blood is composed of plasma and formed elements.The plasma contains 91.5% water, 7% proteins and 1.5% other solutes. The formed elements are platelets, white blood cells, and red blood cells.