Blood Groups and Transfusions page 568

Blood can be typed on the basis of the surface structures of its cells.

1. Antigens and antibodies a. Red blood cell membranes may contain antigens, and blood plasma may contain antibodies.

b. Blood typing uses known antibodies to identify antigens on red blood cell membranes.

2. ABO blood group a. Blood can be grouped according to the presence or absence of antigens A and B.

b. Whenever antigen A is absent, antibody anti-A is present; whenever antigen B is absent, antibody anti-B is present.

c. Adverse transfusion reactions are avoided by preventing the mixing of red blood cells that contain an antigen with plasma that contains the corresponding antibody.

d. Adverse reactions are due to agglutination (clumping) of the red blood cells.

3. Rh blood group a. Rh antigens are present on the red blood cell membranes of Rh-positive blood; they are absent in Rh-negative blood.

b. If an Rh-negative person is exposed to Rh-positive blood, anti-Rh antibodies are produced in response.

c. Mixing Rh-positive red cells with plasma that contains anti-Rh antibodies agglutinates the positive cells.

d. If an Rh-negative female is pregnant with an Rh-positive fetus, some of the positive cells may enter the maternal blood at the time of birth and stimulate the maternal tissues to produce anti-Rh antibodies.

e. Anti-Rh antibodies in maternal blood may pass through the placental tissues and react with the red blood cells of an Rh-positive fetus.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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