Production and Degradation of Blood Cells

In vertebrates, the various cells of blood are made in the bone marrow in a process called hematopoiesis, which includes erythropoiesis, the production of red blood cells; and myelopoiesis, the production of white blood cells and platelets. During childhood, almost every human bone produces red blood cells; as adults, red blood cell production is limited to the larger bones: the bodies of the vertebrae, the breastbone (sternum), the ribcage, the pelvic bones, and the bones of the upper arms and legs. In addition, during childhood, the thymus gland, found in the mediastinum, is an important source of T lymphocytes. There are recent reports that the lungs may also be the site of hematopoiesis.The proteinaceous component of blood (including clotting proteins) is produced predominantly by the liver, while hormones are produced by the endocrine glands and the watery fraction is regulated by the hypothalamus and maintained by the kidney.

Healthy erythrocytes have a plasma life of about 120 days before they are degraded by the spleen and the Kupffer cells in the liver. The liver also clears some proteins, lipids, and amino acids. The kidney actively secretes waste products into the urine.

History Of Blood Group Invention By Karl Landsteiner

Karl Landsteiner

Two blood group systems were discovered by Karl Landsteiner during early experiments with blood transfusion: the ABO group in 1901and in co-operation with Alexander S. Wiener the Rhesus group in 1937. Development of the Coombs test in 1945, the advent of transfusion medicine, and the understanding of ABO hemolytic disease of the newborn led to discovery of more blood groups, and now 33 human blood group systems are recognized by the International Society of Blood Transfusion (ISBT), and in the 33 blood groups, over 600 blood group antigens have been found;many of these are rare or are mainly found in certain ethnic groups.

Czech serologist Jan Janský is credited with the first classification of blood into the four types (A, B, AB, O) in 1907, which remains in use today. Blood types have been used in forensic science and were formerly used to demonstrate the impossibility of paternity (e.g., a type AB man cannot be the father of a type O infant), but both of these uses are being replaced by genetic fingerprinting, which provides greater certainty.

According to the Austrian Federal Ministry of Health[full citation needed] the original terminology used by Karl Landsteiner in 1901 for the classification is A, B and 0 (zero); the "O" (oh) found in the ABO group system is actually a subsequent variation occurred during the translation process, probably due to the similar shape between the number 0 and the letter O.