Blood donation - it won't cost you anything

It has been estimated that about 3 M red blood cells of the human blood die every day but 4 times that number is made in the bone marrow every day. so when we donate blood to save the life of another person, then the loss of blood from our body can be made up very quickly, within a day.

because the red blood cells are made in our bone marrow very fast. Why blood donation is important. Blood donation is the biggest donation. Your blood donation can save the life of a needy person.

There are four major blood groups determined by the presence or absence of two antigens – A and B – on the surface of red blood cells. They are:

  • blood group A, 
  • Blood group B, 
  • Blood group AB, 
  • Blood group O.

blood group

In addition to the A and B antigens, there is a protein called the Rh factor, which can be either present (+) or absent (–), creating the 8 most common blood types (A+, A-,  B+, B-,  O+, O-,  AB+, AB-). A patient can receive blood that has the same ABO antigens as theirs, plus. Rh+ can receive Rh+ or Rh-, while Rh- must receive Rh- blood.

Rh-negative blood is given to Rh-negative patients, and Rh-positive or Rh-negative blood may be given to Rh-positive patients. The rules for plasma are the reverse.

Universal red blood cell donor

The universal red cell donor has to Type O negative blood.

Universal plasma cell donor

The universal plasma donor has Type AB blood

Conclusion of blood donation

There are four types of blood, which are A, B, AB, and O. The basis of these blood types is the presence or absence of certain antigens, called agglutinogens, on the surface of the erythrocytes. The red cells of an individual contain antigens on their surfaces that correspond to their blood group and antibodies in the serum that identify and combine with the antigen sites on the surfaces of red cells of another type. The reaction between red cells and corresponding antibodies usually results in clumping—agglutination—of the red cells; therefore, antigens on the surfaces of these red cells are often referred to as agglutinogens.                         

Antibodies are part of the circulating plasma proteins known as immunoglobulins, which are classified by molecular size and weight and by several other biochemical properties. Most blood group antibodies are found either on immunoglobulin G (IgG) or immunoglobulin M (IgM) molecules, but occasionally the immunoglobulin A (IgA) class may exhibit blood group specificity. 
  • The erythrocytes of type A blood carry agglutinogen A;
  • those of type B blood carry agglutinogen B.
  • Type O blood has neither of these agglutinogens,
  • while type AB has both A and B agglutinogens. 

Rh factor is the type of protein on the surface of red blood cells. those people who have Rh factor are positive and those people who do not have Rh factor are Rh-negative
These agglutinogens react with certain antibodies, called agglutinins, that may be present in the plasma.

Agglutinin is a specific type of antibody. An antibody is a protein that helps in identifying invaders. Antibodies are made by a special type of immune cell called the B cell. They are meant to help target pathogens so that they can be removed from the body.

Agglutinogen is an antigen or foreign cell that gets the immune system reacting, which generates agglutinins.

An agglutinin-agglutinogen reaction causes the cells to adhere to each other. This clumping, or agglutination, would then block the small blood vessels in the body, causing death.

Agglutination is simply the clumping of erythrocytes by agglutinins. The blood clotting mechanism or co­agulation is not involved.
  • A Type A person has the A antigen (agglutinogen) and the anti-B antibody (agglutinin).
  • A Type B person has the B antigen and anti-A antibody.
  • A Type O person has no antigens but both anti­bodies. Conversely,
  • A Type AB person has both antigens but no antibodies.

Basically, a person does not have the agglutinin in his plasma which would clump his own red blood cells.


A summary of the antibodies and anti­gens that each blood type contains is outlined in the following table:

Blood Type:                             Agglutinogens (antigens):            Agglutinins (antibodies):

   A-                                                     A                                                   anti-B

   B-                                                     B                                                   anti-A

  AB-                                                   A and B                                         none

  O -                                                     none                                              anti-A and anti-B

Blood typing is a critical factor in blood trans­fusions. Since the agglutinins in the plasma of one type will react with the agglutinogens on the erythrocytes of the other types, transfusions are usually between people with the same blood type. However, one may use another blood type provided that the transfusion is small and the plasma of the recipient and the erythrocytes of the donor are compatible (does not cause a reaction).


Pawan is injured and badly needs a blood transfusion. He types B. His friend Lala volunteers, but he has type O blood. The physician, in view of the urgency of the situation, uses Lala's blood anyway. A few months later, Lala needs a transfusion. Pawan volunteers but the physician turns him down. why Explain.

This type of transfusion was performed in the given case.

Type O blood from Lala was given to Pawan, a blood-type B patient. The anti-A agglutinin in Pawan's plasma finds no agglutinogens to attack Lala's erythrocytes. We can usually ignore the agglutinin, specifically anti-B, in

Lala's plasma, which would normally react with the agglutinogen B on Pawan's erythrocytes. This is because Lala's plasma is sufficiently diluted during transfusion so that the con­centration of agglutinins is too low to cause appreciable agglutination. Lala's blood, type O, can be given to any­one since her erythrocytes contain no agglutinogens.

Type O blood is therefore called the universal donor. Although type O blood can be donated to any type, it can only accept type O since it has the agglutinins, anti-A, and anti-B, which react with the agglutinogens of every other blood type.

In contrast, type AB blood can receive from any type since it has no agglutinins in its plasma to react with the donor's erythrocytes. Type AB blood is therefore called the universal recipient. But it can only donate to other AB patients since its agglutinogens, A and B, react with the plasma of every other type.

The reason Lala's offer was turned down is that his blood, type B, would agglutinate with Lala's blood, type O. The agglutinins in Lala's
plasma, specifically anti-B, would react with the B agglutinogen on Pawan's erythrocytes and cause agglutination.

The major blood types:

Your blood type is determined by the antigens it contains. There are two major types of blood antigens: ABO and Rh, which combine to create blood types: O+. O-, A+, A-, B+, B-, AB+ ,AB-

If your blood type is: You can give to                            You can receive from:

O Positive                                       O+, A+, B+, AB+                                     O+, O-
A Positive                                                     A+, AB+                       A+, A-, O+, O-
B Positive                                                      B+, AB+                       B+, B-, O+, O-
AB Positive                                                AB+ Only                         All blood types
O Negative                                        All blood types                          O- only
A Negative                                    A-, A+, AB-, AB+                         A-, O-
B Negative                                     B-, B+, AB-, AB+                         B-, O-
AB Negative                                               AB-, AB+                         AB-, A-, B-, O-

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