ihmisveren

ihmisveren, or human blood, is a circulating body fluid that transports oxygen, nutrients, hormones, and waste products, and plays a central role in immune defense and hemostasis. It consists of plasma—the pale-yellow liquid that contains proteins, electrolytes and clotting factors—and cellular elements: red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).

Blood type systems, most notably ABO and Rh(D), determine transfusion compatibility. Matching donor and recipient helps prevent immune reactions such as hemolysis. Compatibility testing and crossmatching are routinely performed before transfusion.

Blood donation is typically voluntary and altruistic. Collected blood is tested for infections, screened for donor eligibility, and processed into components (red cells, plasma, platelets). Units are stored under defined conditions: red cells at 1–6°C for up to about 42 days; platelets at room temperature for up to 5 days; plasma frozen and stored at low temperature for up to a year or more.

Transfusion practices aim to deliver safe, compatible products. Leukoreduction and irradiation are used in some cases to reduce immune reactions and prevent certain complications. Risks include transfusion reactions and alloimmunization; careful donor screening and surveillance mitigate these risks.

Cultural note: The concept of blood groups was identified by Karl Landsteiner in the early 20th century, enabling safer transfusions.