blood type(redirected from A-positive)
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See blood group.
(Medicine) another name for blood group
any of various classes into which human blood can be divided according to immunological compatibility based on the presence or absence of specific antigens on red blood cells. Also called blood type. Compare ABO system, Rh factor.
Any of the four main types into which human blood is divided: A, B, AB, and O. Blood types are based on the presence or absence of certain substances, called antigens, on red blood cells. Also called blood group.
Did You Know? Blood transfusions used to be a doctor's treatment of last resort, since they often caused people to get sick and die. But in the 1890s, a scientist named Karl Landsteiner began to solve the transfusion puzzle. He found that all human red blood cells belonged to one of four groups, or blood types, which he named A, B, AB, and O. The types refer to substances, called antigens, found on the surface of these cells. Antibodies circulating in a person's blood normally recognize the antigens in that same person's blood cells and don't react with them. However, if a person with one blood type is given blood of another type, the antibodies bind to the foreign antigens, causing clumping of the blood and other serious reactions. Thus the key to the transfusion puzzle is to give a person blood that has matching antigens. Today, hospitals always test a blood sample before a transfusion to make sure there is a good match.
Any of various types of blood (notably A, B, AB, O, Rh-positive, Rh-negative) named for the antigen(s) they do or do not contain. Mismatched blood transfusions cause adverse reactions in recipients.
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|Noun||1.||blood type - human blood cells (usually just the red blood cells) that have the same antigens|
blood - the fluid (red in vertebrates) that is pumped through the body by the heart and contains plasma, blood cells, and platelets; "blood carries oxygen and nutrients to the tissues and carries away waste products"; "the ancients believed that blood was the seat of the emotions"
group O, type O, O - the blood group whose red cells carry neither the A nor B antigens; "people with type O blood are universal donors"
Rh positive, Rh-positive blood type - the blood group (approximately 85% of people) whose red cells have the Rh factor (Rh antigen)