Service to Humanity is Service to God

Blood - Overview

  • Intoduction
  • Who can/can't donate blood
  • Why Donate Blood
  • Blood Donation Process

Blood… An introduction

Blood is the river of life that flows through the human body. We cannot live without it. The heart pumps blood to all our body cells, supplying them with oxygen and food. At the same time, blood carries carbon dioxide and other waste products from the cells. Blood also fights infection, keeps our temperature steady, and carries chemicals that regulate many body functions. Finally, blood even has substances that plug broken blood vessels and so prevent us from bleeding to death.

The amount of blood in our body depends on our size and the altitude at which we live. An adult who weighs 160 pounds (73 kilograms) has about 5 quarts (4.7 liters) of blood. An 80-pound (36-kilogram) child has about half that amount, and an 8-pound (3.6-kilogram) infant has about 81/2 ounces (250 milliliters). People, who live at high altitudes, where the air contains less oxygen, may have upto 2 quarts (1.9 liters) more blood than people who live in low regions.

Blood Groups, Blood Typing and Blood Transfusions


The discovery of blood groups


Experiments with blood transfusions, the transfer of blood or blood components into a person's blood stream, have been carried out for hundreds of years. Many patients have died and it was not until 1901, when the Austrian Karl Landsteiner discovered human blood groups, that blood transfusions became safer.

Mixing blood from two individuals can lead to blood clumping or agglutination. The clumped red cells can crack and cause toxic reactions. This can have fatal consequences. Karl Landsteiner discovered that blood clumping was an immunological reaction which occurs when the receiver of a blood transfusion has antibodies against the donor blood cells.

Karl Landsteiner's work made it possible to determine blood types and thus paved the way for blood transfusions to be carried out safely. For this discovery he was awarded the Nobel Prize in Physiology or Medicine in 1930.


What is blood made up of?


An adult human has about 4–6 liters of blood circulating in the body. Among other things, blood transports oxygen to various parts of the body.

Blood consists of several types of cells floating around in a fluid called plasma.

The red blood cells contain hemoglobin, a protein that binds oxygen. Red blood cells transport oxygen to, and remove carbon dioxide from, the body tissues.

The white blood cells fight infection.

The platelets help the blood to clot, if you get a wound for example.

The plasma contains salts and various kinds of proteins.


What are the different blood groups?


The differences in human blood are due to the presence or absence of certain protein molecules called antigens and antibodies. The antigens are located on the surface of the red blood cells and the antibodies are in the blood plasma. Individuals have different types and combinations of these molecules. The blood group you belong to depends on what you have inherited from your parents.

There are more than 20 genetically determined blood group systems known today, but the ABO and Rh systems are the most important ones used for blood transfusions. Not all blood groups are compatible with each other. Mixing incompatible blood groups leads to blood clumping or agglutination, which is dangerous for individuals.

Nobel Laureate Karl Landsteiner was involved in the discovery of both the ABO and Rh blood groups.



ABO blood grouping system



According to the ABO blood typing system there are four different kinds of blood types: A, B, AB or O (null).


Blood group A
If you belong to the blood group A, you have A antigens on the surface of your red blood cells and B antibodies in your blood plasma.


Blood group B
If you belong to the blood group B, you have B antigens on the surface of your red blood cells and A antibodies in your blood plasma.


Blood group AB
If you belong to the blood group AB, you have both A and B antigens on the surface of your red blood cells and no A or B antibodies at all in your blood plasma.


Blood group O
If you belong to the blood group O (null), you have neither A or B antigens on the surface of your red blood cells but you have both A and B antibodies in your blood plasma.



Rh factor blood grouping system


Many people also have a so called Rh factor on the red blood cell's surface. This is also an antigen and those who have it are called Rh+. Those who haven't are called Rh-. A person with Rh- blood does not have Rh antibodies naturally in the blood plasma (as one can have A or B antibodies, for instance). But a person with Rh- blood can develop Rh antibodies in the blood plasma if he or she receives blood from a person with Rh+ blood, whose Rh antigens can trigger the production of Rh antibodies. A person with Rh+ blood can receive blood from a person with Rh- blood without any problems.



Blood group notation

According to above blood grouping systems, you can belong to either of following 8 blood groups:



A Rh+

B Rh+

AB Rh+

O Rh+

A Rh-

B Rh-

AB Rh-

O Rh-



Blood typing – how do you find out to which blood group someone belongs?



1. You mix the blood with three different reagents including either of the three different antibodies, A, B or Rh antibodies.

2. Then you take a look at what has happened. In which mixtures has agglutination occurred? The agglutination indicates that the blood has reacted with a certain antibody and therefore is not compatible with blood containing that kind of antibody. If the blood does not agglutinate, it indicates that the blood does not have the antigens binding the special antibody in the reagent.

3. If you know which antigens are in the person's blood, it's easy to figure out which blood group he or she belongs to!

What is happening when the blood clumps or agglutinates?

For a blood transfusion to be successful, AB0 and Rh blood groups must be compatible between the donor blood and the patient blood. If they are not, the red blood cells from the donated blood will clump or agglutinate. The agglutinated red cells can clog blood vessels and stop the circulation of the blood to various parts of the body. The agglutinated red blood cells also crack and its contents leak out in the body. The red blood cells contain hemoglobin which becomes toxic when outside the cell. This can have fatal consequences for the patient.

The A antigen and the A antibodies can bind to each other in the same way that the B antigens can bind to the B antibodies. This is what would happen if, for instance, a B blood person receives blood from an A blood person. The red blood cells will be linked together, like bunches of grapes, by the antibodies. As mentioned earlier, this clumping could lead to death.

People with blood group    O - "universal donors" & people with blood group AB - "universal receivers".


Blood transfusions – who can receive blood from whom?


Of course you can always give A blood to persons with blood group A, B blood to a person with blood group B and so on. But in some cases you can receive blood with another type of blood group, or donate blood to a person with another kind of blood group.

The transfusion will work if a person who is going to receive blood has a blood group that doesn't have any antibodies against the donor blood's antigens. But if a person who is going to receive blood has antibodies matching the donor blood's antigens, the red blood cells in the donated blood will clump.

Blood Group



Can give blood to

Can receive blood from


A and B



AB, A, B, O




A and AB

A and O




B and AB

B and O



A and B

AB, A, B, O


Who can/can't donate blood

Let others benefit from your good health. Do donate blood if...

  • You are between age group of 18-60 years.
  • Your weight is 45 kgs or more.
  • Your haemoglobin is 12.5 gm% minimum.
  • Your last blood donation was 3 months earlier.
  • You are healthy and have not suffered from malaria, typhoid or other transmissible disease in the recent past.

There are many, many people who meet these parameters of health and fitness!

Do abide by our rules - be truthful about your health status!

We ensure the health of blood, before we take it, as well as after it is collected. Firstly, the donor is expected to be honest about his or her health history and current condition. Secondly, collected blood is tested for venereal diseases, hepatitis B & C and AIDS.
You have to be healthy to give 'safe blood' .

Do not donate blood if you have any of these conditions

  • Cold / fever in the past 1 week.
  • Under treatment with antibiotics or any other medication
  • Cardiac problems, hypertension, epilepsy, diabetes (on insulin therapy), history of cancer, chronic kidney or liver disease, bleeding tendencies, venereal disease etc
  • Major surgery in the last 6 months
  • Vaccination in the last 24 hours
  • Had a miscarriage in the last 6 months or have been pregnant / lactating in the last one year
  • Had fainting attacks during last donation
  • Have regularly received treatment with blood products
  • Shared a needle to inject drugs / have history of drug addiction
  • Had sexual relations with different partners or with a high risk individual
  • Been tested positive for antibodies to HIV
  • Malaria (within 1 year)
  • Hepatitis B, C *
  • Any other type of Jaundice (within 16 years)
  • AIDS
  • Tuberculosis (within 2 years)
  • Diabetes (are you under medication currently?)
  • Fits / Convulsions (are you under medication currently?)
  • Cancer *
  • Leprosy or any other infectious diseases
  • Any allergies (Only if you are suffering from severe symptoms)
  • Hemophilia / Bleeding problems *
  • Kidney disease *
  • Heart disease *
  • Chicken Pox (within 1 year)
  • Hormonal disorders *
  • Hemoglobin deficiency / Anemia (recently)
  • Drastic weight loss (recently)
  • Small Pox Vaccination (within the last 3weeks)
  • Blood Donation (within the last 3 months)
  • Blood Transfusion (within the last 6 months)
  • Major Surgery (within the last 3 months)
  • Pregnancy (within the last 6 months)
  • Organ Transplant (within one year)
    * Highly restricted.

Pregnancy and Menstrual Period

  • Females should not donate blood during pregnancy
  • They can donate after 6 weeks following a normal delivery and when they are not breast feeding
  • Females should not donate blood if they are having heavy menstrual flow or menstrual cramps

Why Donate Blood

Blood is the part of life that is given to those who need it by those who have the resource to satisfy the need.
Your blood donation may be even more special than you realize.
A single donation from you can help one or more patients. This is possible because whole blood is made up of several useful components. These components perform special functions in your body and in the body of patients who receive your blood. The various blood components are Red Blood Cells, White Blood Cells, Platelets, Plasma and selected Plasma Proteins. Each of these components can be separated from your donated volume of blood and transfused into a specific patient requiring that particular component. Thus, many can benefit from one unit of blood.

Blood is needed every minute

  • To replace blood lost because of accidents or diseases.
  • To treat shock due to injury.
  • For Major & Minor surgeries including open heart surgeries, transplants etc.
  • For burn victims.
  • For patients suffering from Anemia.
  • During child birth for the mother.
  • For exchange transfusion for new born infants.
  • To make blood derivatives which are used to treat medical problems.
  • For children suffering from ailments like Thalassaemia, Hemophilia (bleeding disorders) , Leukemia, Blood Cancer.

Blood Donation Process

Donating blood is safe and simple. It takes approximately 10-15 minutes to complete the blood donation process. Any healthy adult between 18 years and 60 years of age can donate blood. This is what you can expect when you are ready to donate blood:

  • You walk into a reputed and safe blood donation centre or a mobile camp organised by a reputed institution.
  • A few questions will be asked to determine your health status (general questions on health, donation history etc). Usually you will be asked to fill out a short form.
  • Then a quick physical check will be done to check temperature, blood pressure, pulse and haemoglobin content in blood to ensure you are a healthy donor.
  • If found fit to donate, then you will be asked to lie down on a resting chair or a bed. Your arm will be thoroughly cleaned. Then using sterile equipments blood will be collected in a special plastic bag. Approximately 350 ml of blood will be collected in one donation. Those who weigh more than 60 Kg can donate 450 ml of blood.
  • Then you must rest and relax for a few minutes with a light snack and something refreshing to drink. Some snacks and juice will be provided.
  • Blood will be separated into components within eight hours of donation.
  • The blood will then be taken for testing.
  • Once found safe, it will be kept in special storage and released when required.
  • The blood is now ready to be given to the hospital, to save lives.

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