The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
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Until 1900, no one understood why blood could not be transfused from one person to another without occasional difficulties. Viennese pathologist Karl Landsteiner was the first to discover that not everyone's blood is exactly alike, and actually can be divided into four primary groups or types: A, B, AB, and O.
The various blood types are identified according to the various proteins, or antigens, on the surface of blood cells, and the antibodies to other antigens. Antibodies react to antigens as part of the body's defense mechanism to protect the blood supply, by combining with them chemically. One person with a blood antigen type A, for example, will have antibodies to blood type B, and vice versa. Some people have both A and B antigens (thus the AB blood type) and do not have antibodies for either group, or the O group. Those with this type of blood are called the "universal recipient," because they can receive blood from A, B or O donors. Approximately half of the world's population has antibodies to both A and B antigens, and make up the O group. They are called the "universal donors" because they can provide blood to people with all other blood types.
Since blood with one blood type's antigen does not carry antibodies to that particular antigen, blood of the same type can be easily transferred and mixed. Transfusing blood from one person to another is a common transplant today, but it is essential that the correct blood type be given to the recipient. If he or she has antibodies to the transfused blood type or antigens, an immune reaction occurs and the red cells in the blood clump together.