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ONE TWO THREE FOUR

Mastering Medical

Terminology

Essential of Human

Anatomy and Physiology

Mosby’s Dictionary KENHUB

By Sue Walker, Maryann Wood

and Jenny Nicol

By Elaine Marieb and Suzanne

Keller

By Mosby www.kenhub.com

Introduction

3Khaleel Alyahya, PhD, MEd

▪ Although there are many blood group systems with

several subtypes, the two best-known ways of classifying

blood are the ABO group system and the Rhesus (Rh) type

system.

▪ In the former, there are four main blood groups, known as

types A, B, AB and O which are identified based on

combinations of inherited antigens and antibodies present on

the surface of red blood cells.

History


▪ The ABO blood group system was first identified by an Austrian

scientist Dr Landsteiner in 1901.

▪ Dr Landsteiner recognized the reactions between the blood antigens

and certain antibodies in the plasma that caused the blood serum of

some people to clump the blood of others.

▪ After further experimentation, he formally identified the four mutually

incompatible blood groups (A, B, AB, O) based on the presence or

absence of the two specific antigens, A and B.

▪ Later in his career Landsteiner identified the Rhesus factor.

ABO System


▪ These blood types are determined by the absence of a particular

antigen corresponding to the presence of an antibody for that antigen.

Therefor:

▪ If a person is blood group A, they will have A antigens on their red

blood cells and antibodies to antigen B in their plasma.

▪ If the individual is blood group B, they will have B antigens on their

red blood cells and antibodies to antigen A in their plasma.

▪ People who have blood type AB have both A and B antigens on their

red blood cells, so do not have antibodies to either A or B in their

plasma.

▪ Individuals with blood type O have no A or B antigens but have

antibodies to both A and B in their plasma, thus, this type of blood can

give blood to any other types.

Rhesus Factor


▪ Blood type is also determined by a pair of inherited genes known as

the Rhesus (Rh) factor.

▪ Rhesus factor, or Rh factor as it is also called, was first identified in

the blood of Rhesus monkeys.

▪ These small monkeys were often used for medical

experimentation.

▪ A person is either Rh-positive or Rh-negative, depending on the

presence or absence of the inherited Rhesus protein in their red blood

cells.

▪ A person who is Rh-negative will experience a severe immune

system reaction if Rh-positive blood gets into their bloodstream

because the body creates antibodies against the foreign protein.

▪ This can occur during a mismatched transfusion or through the

placenta during a second or subsequent pregnancy where the

mother is Rh-negative, and the baby inherits Rh-positive blood from

its father.

Blood Transfusion


▪ A blood transfusion is the transfer of blood or blood products from adonor to a recipient.

▪ It may be given to replace the blood of a patient followinghaemorrhage, surgery, injury or certain illnesses such as anaemia.

▪ The blood used in a transfusion must be compatible with the bloodtype of the recipient; otherwise, an antibody reaction calledagglutination will result.

▪ It is always preferable for patients to be transfused with blood of thesame ABO and Rh groups as they have themselves.

▪ If a person undergoing transfusion of blood has a blood group thatdoes not have any antibodies against the antigens present in thedonor blood, all will be well.

▪ However, if the recipient’s blood has antibodies which match theantigens in the donated blood, agglutination or binding of the redblood cells in the donated blood will occur.

▪ In an emergency, however, if the required blood group is notavailable, it is possible for a patient to be given a different group asfollows.

Donors


▪ A person with type O blood is known as the universal donor

because type O blood can be given to a person with any blood type.

However, a person with type O blood can only receive type O blood.

▪ A person with type AB blood is known as the universal recipient

because they can receive type A, B, AB or O blood.

▪ A person with type A blood can receive a transfusion of types A and

O blood.

▪ For a type B recipient, the blood transfusion must be type B or type

O.

▪ However, the Rh factor must always be compatible between the

donor and the recipient.

▪ A blood transfusion may consist of ‘whole blood’, containing both the

plasma and cellular components of blood, or only the red cells known

as packed cells.

▪ This type of transfusion is normally given to a patient who is lacking

red blood cells because of anaemia.

Blood Analysis


▪ Haematology is a general term for the study of blood.

▪ Within the specialty of haematology, there are several different

categories of blood tests that may be performed by a laboratory.

▪ All tests compare a patient’s results against a ‘reference range’.

▪ The reference range represents the average value for a ‘normal’

population group, generally with any expected variation that may be

seen (usually plus or minus 2 standard deviations from the average).

▪ Reference ranges are set by the laboratory that provides the test

results, and different laboratories use varying equipment and testing

methods.

▪ That means each laboratory has its own references ranges, and

these may differ from laboratory to laboratory.

▪ Therefore, results from one laboratory cannot always be compared

with those from another laboratory.

▪ See page 539 for examples of standard haematological values.

Transfusion Reactions


▪ Transfusion reactions occur when mismatched blood is infused.

▪ Donor’s cells are attacked by the recipient’s plasma antibodies

causing:

• Diminished oxygen-carrying capacity.

• Clumped cells that impede blood flow.

• Ruptured RBCs that release free hemoglobin into the bloodstream.

▪ Circulating hemoglobin precipitates in the kidneys and causes renal

failure.

Blood Types & Reactions


Blood Type Testing


Rh Factors & Pregnancy


Blood Tests

Haematology


▪ Haematology specifically looks at blood and bone marrow to

identify cancers of the blood (such as leukaemia and

lymphoma) and clotting disorders.

▪ Blood grouping and antibody testing for blood banking is also

done by haematology as is the most commonly ordered test —

a full blood count.

Biochemistry


▪ Biochemistry assesses the levels of chemicals in the body to

determine if a disease is present or not.

▪ Biochemistry tests include electrolytes, liver function tests,

cholesterol, triglycerides, lipids, blood glucose and drug levels.

Cytogenetics


▪ This is a new area of study which examines genes and

chromosomes.

▪ It is concerned with genetic testing and cancer diagnosis.

▪ Cytogenetic tests can be performed on blood, bone marrow,

fetal specimens, and body tissues.

Microbiology


▪ Microbiology looks for infections such as viruses, bacteria,

parasites in blood as well as other body tissues.

Serology


▪ Serology examines blood serum for antibodies to specific

infections such as influenza, rubella, Epstein-Barr virus, Ross

River fever and to various allergens.

▪ By performing a serology test, it is possible to determine a

patient’s infection status or if they have responded to an

immunization.

Venepuncture


▪ Venepuncture is the process of obtaining intravenous access for the

purpose of intravenous therapy or for blood sampling of venous blood.

▪ In healthcare, this procedure is performed by medical laboratory

scientists, medical practitioners, and some other technicians and

nursing staff.

▪ It is essential to follow a standard procedure for the collection of blood

specimens to get accurate laboratory results.

▪ Any error in collecting the blood or filling the test tubes may lead to

erroneous laboratory results.

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