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By the end of this section, you will be able to:
  • Describe the two basic physiological consequences of transfusion of incompatible blood
  • Compare and contrast ABO and Rh blood groups
  • Identify which blood groups may be safely transfused into patients with different ABO types
  • Discuss the pathophysiology of hemolytic disease of the newborn

Blood transfusions in humans were risky procedures until the discovery of the major human blood groups by Karl Landsteiner, an Austrian biologist and physician, in 1900. Until that point, physicians did not understand that death sometimes followed blood transfusions, when the type of donor blood infused into the patient was incompatible with the patient’s own blood. Blood groups are determined by the presence or absence of specific marker molecules, called antigens, on the plasma membranes of erythrocytes. With their discovery, it became possible for the first time to match patient-donor blood types and prevent transfusion reactions and deaths.

Antigens, antibodies, and transfusion reactions

Antigens are substances that the body does not recognize as belonging to the “self” and that therefore trigger a defensive response from the leukocytes (WBC) of the immune system. Here, we will focus on the role of immunity, antigens, and antibodies in blood transfusion reactions.

Antigens are generally large proteins, but may include other classes of organic molecules, including carbohydrates, lipids, and nucleic acids. Following an infusion of incompatible blood, erythrocytes with foreign antigens appear in the bloodstream and trigger an immune response. Proteins called antibodies (immunoglobulins), which are produced by certain B lymphocytes called plasma cells, attach to the antigens on the plasma membranes of the infused erythrocytes and cause them to stick to one another (i.e. agglutinate). The clumps of erythrocytes block small blood vessels throughout the body, depriving tissues of oxygen and nutrients. As the erythrocyte clumps are degraded, in a process called hemolysis    , their hemoglobin is released into the bloodstream. This hemoglobin travels to the kidneys, which are responsible for filtration of the blood. However, the load of hemoglobin released can easily overwhelm the kidney’s capacity to clear it, and the patient can quickly develop kidney failure.

More than 50 antigens have been identified on erythrocyte membranes, but the most significant in terms of their potential harm to patients are classified in two groups: the ABO blood group and the Rh blood group.

The abo blood group

Although the ABO blood group    name consists of three letters, ABO blood typing designates the presence or absence of just two antigens, A and B. Both are glycoproteins. People whose erythrocytes have A antigens on their erythrocyte membrane surfaces are designated blood type A, and those whose erythrocytes have B antigens are blood type B. People can also have both A and B antigens on their erythrocytes, in which case they are blood type AB. People with neither A nor B antigens are designated blood type O. ABO blood types are genetically determined.

Questions & Answers

Help me am confused what is the cell membrane as a partially permeable membrane
Janelle Reply
it is the ability of a molecules to cross a cell membrane depending on their both size and chemical properties.
Andrews
Based on my previous understanding of biological systems, a cell membrane is a semi-permeable membrane made up of a phospholipids bi-layer. The polar head consisting of phosphate and the hydrophobic end made up of lipids.
Abayomi
Smallest bone of rabbit is
Sahrukh Reply
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Rodrick Reply
Describe how a healthy pregnancy could be maintained
Rodrick
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Sahrukh
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Samllest bone
Sahrukh
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AlfredOfficial Reply
by DNA tests
lasford
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AlfredOfficial
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R.k Reply
208
Rani
A baby's body has about 300 bones at birth. These eventually fuse (grow together) to form the 206 bones that adults
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R.k
A baby's body has about 300 bones at birth. These eventually fuse (grow together) to form the 206 bones that adults h
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R.k
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Manali
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R.k
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Manali
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Rani
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Jasper
babies have 300 bones in which it fuses to become 206 as an adult.
Andrews
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Nchimunya
figure of male reproduction
Rani Reply
front view of male reproductive system
Rani
front view of male reproductive system
Rani
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Rhonda Reply
Actin is a family of globular multi-functional proteins that form microfilaments. 
Lauren
difference between throat and lyrnx
Lone
what is the difference between a vaccine and a antiserum
Silver Reply
An antiserum contains antibodies already produced and is used to pass on immune responses. A vaccine contains a substance that stimulates the production of antibodies to create an immune response.
Nana
A vaccine a preparation of antigens for one (or more) diseases that is given to stimulate active immunity and protect against the disease (s). while an antiserum either neutralizes the "infection " or stimulates your immune system to attack an infection.
Oliver
what is deoxyribonucleic acid
Carlene Reply
A negatively charged molecule; polymer of nucleotides found in the nucleus of a cell ... DNA.
Abayomi
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Asali
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Janelle
hi
Oliver
hello
Rani
how are you doing?
Jasper
DNA is genetic material which is present in cell DNA is made up of nitrogen base,phosphate group and pentose sugar.
Manali
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Jasper
give a front view of male reproductive system
Rani
to maintain certain biological activities of cell
jeeni Reply
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Shaili Reply
caused by two different agents.. malaria is caused by Culex mosquito in birds and Anopheles in humans.. while dengue fever is caused by Aedes mosquito
Rayyan
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Rani
what is oral pilli
Rani
pili is hair like appendages found on cell surface and play important role in cause disease
Manali
correct
Jasper
what is immune system
Shaili Reply
system that defends the body against invading microbes n pathogens... (white blood cells makes immune system)
Rayyan
what is interferon's ?
maya Reply
interferon is any group of glycoproteins, produce by the immune system.
Henry
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Shaili
immune system is the defence mechanism that protect our body to unwanted particles
Manali

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Source:  OpenStax, Human biology. OpenStax CNX. Dec 01, 2015 Download for free at http://legacy.cnx.org/content/col11903/1.3
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