Chap 4. conditions Flashcards
(4 cards)
antigen
usually a foreign substance (such as a poison, virus, or bacterium), stimulates the production of antibodies.
Rh condition
is a antigen-antibody reaction. Rh + has a protein coating (antigen) on his or her red blood cells (RBC’s). Rh - have normal RBC’s but their red cells lack the Rh factor antigen. If a Rh- woman gives birth to a Rh+ baby it is a serious condition. During delivery of the first Rh- baby, some of the baby’s blood cells containing Rh+ antigens can escape into the mothers bloodstream. The sensitizes the mother do that she produces a low level of antibodies to the Rh+ antigen. Because this occurs at delivery the first baby is generally not affected and is normal at birth. Difficulties arise with the second Rh+ pregnancy. If this embryo also is Rh+, during pregnancy the mother’s acquired antibodies (from the first preg.) enter the embryo’s bloodstream. These antibodies attack and destroy the embryo’s Rh+ RBCs. The embryo attempts to compensate for this loss by making new but immature RBC’s called erythroblasts (-blast = immature) The affected infant is born with hemolytic disease of the newborn (HDN) or erythroblastosis fetalis.
Hemolytic disease of the newborn (HDN)
Erythroblastosis fetalis.
HDN can occur in the first preg. if a mother has had an Rh+ blood transfusion. One of the clinical signs of HDN is jaundice. Jaundice results from excessive destruction of RBCs. When RBCs breakdown (hemolysis), the hemoglobin within the cells produces bilirubin ( a chemical pigment). High levels of bilirubin in the bloodstream (hyperbilirubinemia) cause jaundice. To prevent bilirubin from affecting the brian cells of the infant, newborns are treated with exposure to bright lights (phototherapy). The light decomposes the bilirubin, which is excreted from the infant’s body. Physicians administer Rh immunoglobulin to an Rh- woman within 72 hours after each Rh+ delivery, abortion, or miscarriage. The globulin binds to Rh+ cells that escape into the mother’s circulation and prevents formation of Rh+ antibodies. This protects future babies from developing HDN.
antibodies
are protein substances made by white blood cells in response to the presence of foreign antigens The reaction between an antigen and an antibody is an immune response.
