Plasma, the pale yellow liquid component of blood, comprises over half of its total volume. It serves as a complex transport system, carrying numerous substances essential for bodily functions. This article explores its circulation within the body and its journey after donation.
Plasma’s Dynamic Role in the Body
Plasma circulates continuously through the cardiovascular system, forming the fluid medium in which blood cells are suspended. It transports nutrients like glucose, amino acids, and lipids from the digestive system to cells throughout the body. Plasma also moves hormones from endocrine glands to target organs, facilitating communication and regulation.
Beyond transport, plasma plays a role in maintaining the body’s internal balance. Its proteins, particularly albumin, help regulate blood pressure and maintain blood volume by preventing fluid from leaking out of blood vessels into surrounding tissues. Plasma also contributes to temperature regulation by distributing heat throughout the body and acts as a buffer to maintain the blood’s pH balance, which is crucial for cellular function.
Plasma carries components for defense and repair. It transports antibodies (immunoglobulins) that identify and neutralize foreign invaders like bacteria and viruses. Plasma also contains clotting factors, such as fibrinogen, essential for forming blood clots to stop bleeding after an injury.
The Continuous Cycle of Plasma Components
Plasma components continuously exchange and transform. Water and small solutes, including electrolytes, glucose, and amino acids, constantly move between the plasma and the interstitial fluid surrounding cells. This continuous exchange allows cells to receive necessary nutrients and dispose of waste products.
Waste products, such as urea, are transported by plasma to organs for elimination. The kidneys filter these substances from the blood, excreting them in urine. Other metabolic byproducts are carried to the liver for processing or detoxification before being removed from the body.
Plasma proteins undergo synthesis, function, and breakdown. Most plasma proteins, including albumin and many globulins, are produced primarily in the liver. Once synthesized, they perform specific roles like maintaining osmotic pressure, transporting molecules, or participating in immune responses. These proteins are eventually broken down into their constituent amino acids, which can then be recycled by the body to build new proteins or used as a source of energy.
The Path of Donated Plasma
Donated plasma undergoes plasmapheresis, a specialized collection process. During this procedure, blood is drawn from a donor, and a machine separates the plasma from other blood components like red blood cells and platelets. These cellular components are then returned to the donor, allowing for more frequent donations compared to whole blood. Donated plasma is typically frozen within 24 hours to preserve its valuable proteins and can be stored for up to one year.
After collection, donated plasma undergoes extensive processing. Multiple donations are pooled and subjected to fractionation, a purification process. This method uses controlled changes in temperature, pH, and alcohol concentrations to extract specific therapeutic proteins. Rigorous testing for pathogens like HIV and hepatitis is performed throughout this process to ensure safety.
Purified plasma proteins create a range of biopharmaceutical products. These include immunoglobulins, which provide antibodies for individuals with weakened immune systems or certain autoimmune conditions. Clotting factors are manufactured for patients with bleeding disorders such as hemophilia, while albumin is used to treat burn victims, those in shock, or individuals with severe liver disease. Donated plasma also contributes to medical research, aiding in the discovery and development of new treatments.