Human plasma is the yellowish liquid component of blood, making up approximately 55% of its total volume. This fluid transports blood cells throughout the body. It is a fundamental part of the circulatory system, carrying substances necessary for maintaining bodily functions.
The Building Blocks of Plasma
Plasma is primarily composed of water, accounting for about 92% of its volume. This high water content allows plasma to dissolve and transport a wide array of substances throughout the body. Dissolved within this water are various plasma proteins, which constitute about 7% of plasma’s composition. These proteins include albumin and globulins, which play diverse roles such as immunity and transport. Fibrinogen is another significant plasma protein.
Beyond proteins, plasma contains electrolytes like sodium, potassium, and calcium, which regulate nerve and muscle function and maintain the body’s pH balance. Glucose, amino acids, and fats are also present as nutrients, transported by plasma to cells. Hormones travel through plasma to reach their target organs, alongside waste products such as urea and creatinine, which are carried to the kidneys for excretion.
Vital Functions of Plasma
Plasma serves as the primary transportation system within the body, carrying dissolved substances where they are needed. It transports absorbed nutrients like glucose and amino acids to various cells. Hormones are also ferried by plasma to distant target tissues, regulating physiological processes. Plasma transports dissolved gases, including oxygen and carbon dioxide, between the lungs and body tissues.
The immune system relies on plasma for defense against pathogens. Immunoglobulins, also known as antibodies, are plasma proteins that identify and neutralize foreign invaders such as bacteria and viruses. These antibodies circulate within the plasma, providing a protective response against infections. Plasma also contains various clotting factors, notably fibrinogen, which are inactive until an injury occurs. Upon injury, these factors are activated to form a fibrin mesh, which forms a clot to prevent blood loss.
Plasma proteins, particularly albumin, are instrumental in maintaining the body’s fluid and electrolyte balance. They exert osmotic pressure, which helps to retain fluid within the blood vessels, preventing it from leaking into surrounding tissues and causing swelling. Plasma also contributes to thermoregulation by distributing heat throughout the body, helping to maintain a stable internal temperature.
Plasma Donation: A Lifesaving Contribution
Plasma donation, known as plasmapheresis, involves drawing whole blood, separating the plasma, and returning red blood cells and platelets to the donor. This procedure allows individuals to donate plasma more frequently than whole blood, as the body can replenish plasma proteins quickly. The demand for donated plasma is high due to its wide range of medical applications.
Donated plasma is administered directly to patients suffering from severe burns, trauma, or massive blood loss to restore blood volume. It also treats individuals with bleeding disorders, providing the clotting factors they lack. Patients with liver disease also benefit from plasma transfusions.
Beyond direct transfusion, donated plasma is fractionated to produce specific plasma-derived therapies. Intravenous Immunoglobulin (IVIG) is a concentrated form of antibodies used to treat patients with immune deficiencies or autoimmune disorders. Albumin, another plasma-derived product, is used to expand blood volume in patients with severe burns. Clotting factor concentrates are also manufactured from plasma, providing targeted treatment for bleeding disorders. Each plasma donation contributes to the manufacture of these therapies, improving patient quality of life.