1. What is blood made up of?

There are 2 major components of blood -- the liquid portion, which is called plasma, & the solid portion, which includes the various blood cells and platelets.

Plasma contains water, antibodies, clotting factors, nutrients (such as glucose, amino acids, fatty acids & glycerol), oxygen, carbon dioxide, ions, triglycerides,vitamins, minerals, etc.

The solid portion includes erythrocytes (red blood cells), leukocytes (white blood cells), & thrombocytes (platelets).

Red blood cells are the cells that can transport oxygen because they have many iron-containing molecules called hemoglobin that attracts oxygen. White blood cells are an important part of our immune systems & help fight disease. Thrombocytes are fragments of a specialized cell which are needed for the blood clotting process.
 
 

2. What is the difference between "clotting" & "agglutination?" Aren't they the same thing?

No, they are not the same process.

Clotting refers to the hemostasis process that occurs in the body when there has been some injury to a blood vessel & blood loss needs to be stopped. It is a process that involves many steps & is vital to our survival. People whose blood will not properly clot, or coagulate, are in danger of bleeding to death. For example, people with the hereditary condition, hemophilia, are missing one of the several factors needed for normal blood coagulation.

Agglutination refers to the clumping of red blood cells that occurs when different blood types are mixed together. It involves a chemical reaction between antigens on the surface of red blood cells & protein antibodies in the plasma, or liquid, part of the blood. Certain blood types cannot be safely mixed together due to this antigen-antibody reaction. The fact that mixing different blood types together can cause agglutination has been used as a means of typing blood, i.e., determining just what blood type a person has.

For more detailed information on the clotting mechanism & on agglutination, refer to your textbook in the chapter on blood.
 
 

3. What are the major blood types?

Type A, which has the A antigen on the surface of the RBC's & anti-B antibodies in the plasma, or liquid portion of the blood

Type B, which has the B antigen on the surface of the RBC's & anti-A antibodies in the plasma

Type O, which has neither A or B antigens on the surface of the RBC's, but does have both anti-A and anti-B antibodies in the plasma of the blood

Type AB, which has both A antigens & B antigens on the surface of the RBC's but has no anti-A or anti-B antibodies in the plasma of the blood

There are additional rare variations of blood types, but these usually do not come into consideration except in cases of organ or bone marrow transplants.
 
 

4. What is the most common blood type?

The most common blood type of the human ABO blood types is Type O, which includes about 45% of the population.
 
 

5. What is the least common of these 4 blood types?

The least common is Type AB.
 
 

6. Can a person safely receive a blood transfusion that doesn't exactly match his/her blood type?

Yes, if a small transfusion is administered slowly to the recipient of the blood, a person who is Type A, B, or AB can receive a donation of Type O blood. (However, the Type A, B or AB person could NOT safely receive non-matching blood from one of the other blood types because the antibodies in his/her blood would cause agglutination of the in-coming red blood cells.)
 
 

7. What is the Universal Donor?

Since Type O blood does not contain RBC's with A or B antigens on their surface, small donations of this blood type can safely be given to the other 3 blood types; therefore, Type O has been called the "Universal Donor." If the transfusion is done slowly, the anti-A and anti-B antibodies in the Type O plasma will be diluted by the recipient's plasma so they don't cause the agglutination reaction (clumping) of the recipient's cells. Typically, however, every attempt is made to match the donor's blood as closely as possible.
 
 
 

8. What is the Universal Recipient?

Type AB is called the Universal Recipient because this blood type does not contain anti-A or anti-B antibodies. This means that a small donation of Type A or Type B blood will not undergo an agglutination reaction if administered slowly enough to dilute the antibodies contained in the donated blood.
 
 

9. What does the + or - after the letter blood type mean?

What is the Rh factor?

The plus or minus following the letter name of the blood type refers to another blood typing factor, which like the ABO types, is hereditary. It is called the Rh factor (from the name of the Rhesus monkey in which it was first studied). The antigen, if it has been inherited, is located on the red blood cells, as is true for the A & B antigens.

If a person is Rh positive (Rh +), it means he/she has inherited the trait for having the Rh antigen on the RBC's. However,there will not be an antibody in the plasma that fights blood lacking the antigen. Note that this is a feature which is different from the ABO blood typing factors.

If a person is designated as Rh negative, the RBC's do not have the Rh antigen on their surface. However, there will also be no antibodies against the factor in the plasma of the Rh- person. This is another difference from what you have learned about ABO blood typing.

For an Rh- person to have anti-Rh antibodies in the blood, that person must be exposed to blood that has the Rh antigen from an Rh+ person. If such an exposure does occur, a reaction will not occur immediately. The recipient's immune system will produce Rh- antibodies in response to the "foreign" antigen over a period of time. A second exposure to Rh + blood can cause the antigen-antibody reaction that could be fatal to the recipient. Such an exposure could occur during a blood transfusion of Rh + blood into the Rh- person. Another situation in which this could occur is if an Rh- woman becomes pregnant with a baby who is Rh +.

Erythroblastosis fetalis is a condition which can develop when an Rh- woman becomes pregnant with a baby who has inherited the Rh + factor from its father. If the mother happens to be exposed to the baby's Rh antigen-bearing RBC's, she will develop anti-Rh antibodies. Since antibodies are able to diffuse from the mother's blood through the placenta, any Rh + baby she may later carry may develop Erythroblastosis fetalis, which could severely affect the developing baby's blood cells & other systems. For this reason as well as many others, it is very important that all pregnant women, as well as those who plan to become pregnant, receive good medical care to avoid serious health problems for their children. A reaction to the Rh antigen can be avoided if the woman's Rh- condition is detected early in the pregnancy by administering an injection which suppresses the development of antibodies.
 
 

10. What is the relationship between AIDs & hemophilia?

People who have inherited hemophilia require transfusions of certain blood products to supply them with the blood clotting factors which their own bodies are not able to produce. They need the particular factors because, without the factors, the hemophilia patient could potentially bleed to death from a bump or nosebleed which, for a person without the condition, could otherwise be rather minor.

Before the AIDs virus was recognized, there were numerous cases of transfusions of blood which contained the AIDs virus, both to hemophilia patients and to other individuals needing blood transfusions during surgery, for example. These patients developed AIDs because they were exposed through the affected blood. Blood supplies are now screened for the AIDs virus and are considered safe for transfusions.