Plasma is separated from whole blood through a process called blood fractionation, primarily using centrifugation.
Blood Fractionation: Separating Plasma
The process of obtaining plasma from blood relies on the different densities of blood components:
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Collection and Anticoagulation: Whole blood is drawn from a donor or patient into a collection tube. An anticoagulant, such as citrate, is added to prevent the blood from clotting. This is crucial because clotting would trap the plasma within the clot.
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Centrifugation: The blood-filled tube is then placed in a centrifuge, a machine that spins the tube at high speed. This spinning action generates a centrifugal force.
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Density Separation: Due to differences in density, the blood components separate into distinct layers:
- Red Blood Cells (Erythrocytes): These are the densest components and settle at the bottom of the tube.
- White Blood Cells (Leukocytes) and Platelets (Thrombocytes): These form a thin layer above the red blood cells, often called the buffy coat.
- Plasma: Being the least dense, the plasma remains at the top of the tube. Plasma is a clear, yellowish fluid.
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Plasma Extraction: After centrifugation, the plasma layer is carefully poured off or drawn off using a pipette or automated device. This separated plasma is then ready for use in various medical applications or further processing.
Summary
In essence, plasma comes from blood by preventing the blood from clotting and then using a centrifuge to separate the different components based on density. The lighter plasma floats to the top and can then be collected.
