University:
Glendale Community College
Course:
BIO160 | Introduction to Human Anatomy and Physiology
Academic year:

2019
Views:

228

Pages:

13
Author:

Ray Payne

The ABO Group • Your ABO blood type is determined by presence or absence of antigens (agglutinogens) A and/or B on RBCs blood type A has A antigens blood type B has B antigens blood type AB has both A and B antigens blood type O has neither antigen • Frequency of blood types varies among populations, but in the USA, O is the most common and AB is the rarest. Frequency of ABO Blood Groups Population O A B AB Cherokee, NC, USA Pawnee, OK, USA African-American, USA Caucasian, USA Eskimo, USA Nikappu, Japan Bengali, India 95% 58% 51% 46% 47% 31% 30% 4% 40% 25% 42% 45% 38% 26% 2% 3% 19% 9% 6% 22% 36% 0% 0% 4% 4% 2% 9% 7% Agglutinins against the ABO Group Antibodies (agglutinins) against the A and B antigens appear 2-8 months after birth and reach a maximum concentration at 10 about years. – you do not normally produce antibodies that would react against your own antigens (agglutinogens). – each antibody can attach to several antigens at the same time causing agglutination (clumping) of red blood cells. • RBC antigens ABO Blood called agglutinogens A & B – inherited combinations of proteins, glycoproteins and glycolipids on red blood cell membranes • Plasma antibodies called agglutinins anti-A & B – agglutinins are gamma globulins in blood plasma that recognize (stick to) foreign agglutinogens on RBCs – responsible for RBC agglutination in mismatched blood transfusions Types ABO Blood Types Agglutination of Erythrocytes ABO Blood Typing Mismatched Transfusion Reaction • Agglutinated RBCs block blood vessels and RBCs can rupture – free Hb can block kidney tubules and cause death • Universal donors and recipients – AB called universal recipient since it lacks both antibody A and B; O called universal donor – problem is donor’s plasma may have antibodies against recipient’s red blood cells – solution is giving packed cells with minimum plasma The Rh Group • Rh or D agglutinogens were discovered in the Rhesus monkey in 1940, and then a similar system was found in humans. The Rh Group • Blood type is Rh+ if type D agglutinogens are present on RBCs • Anti-D agglutinins are not normally present in blood and only form in Rh- individuals who are exposed to Rh+ blood: – Rh- person gets a blood transfusion of Rh+ blood – Rh- woman carrying an Rh+ fetus • no problems result with either the first transfusion or the first pregnancy – Hemolytic Disease of the Newborn (HDN or erythroblastosis fetalis) occurs if mother has formed anti-D antibodies and is pregnant with 2nd Rh+ child – RhoGAMTM can be given to a pregnant woman with a fetal Rh incompatibility • RhoGAM binds to fetal agglutinogens that get into in the mother’s blood so her immune system will not mount an attack against the fetus during pregnancy Hemolytic Disease of Newborn • • • • • In the first pregnancy, some fetal Rh+ blood crosses into the mother and she slowly develops anti-D agglutinins In second pregnancy, the mother’s antibodies can cross into the fetus and hemolyze the fetal blood causing severe anemia in the baby. Hemolyzed RBCs release hemoglobin which is converted to bilirubin. High bilirubin is toxic to the mother and child and can cause brain damage. Treat with transfusion or UV phototherapy to degrade bilirubin. There is a dominant allele for the D antigen. The genetic pairs that can exist in humans are as follows: Genetic makeup ++ +- - Blood type Rh positive Rh positive Rh negative Parents' Rh types Possible allele combinations Possible Rh in the children Both + Both + Both + Both One + & One One + & One - ++ & ++ ++ & ++- & +-- & -++ & -+ - & -- ++ + + or + + + or + - or - -++ - or - - positive positive positive or negative negative positive positive or negative Frequency of Rh Blood Groups Population Cree, Quebec African-American, USA Caucasian, USA Eskimo, USA Bengali, India + 98% 85% 85% 100% 95% 2% 15% 15% 0% 5%