Blood has five functions: 1. Transport function; 2. Adjustment function; 3. Stop and coagulate blood; 4. Maintain the stable function of the internal environment; 5. Defense function.

Blood products refer to: what patients lack, what to supplement, such as anemia (hemoglobin below 6g), red blood cell transfusion; Platelets below 20,000 or bone marrow transplantation for platelet transfusion; Keywords liver cirrhosis hypoproteinemia, albumin transfusion; Immune diseases, gamma globulin transfusion, etc.