Blood Typing

What's in a speck of blood?
Blood is made up of plasma, red and white blood cells, and platelets. 
 
 

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Here is a close-up view.
 

 
 
 
 
How much blood is in our body?
A newborn baby has about half a pint (one cup) of blood in his or her body.  An adult has roughly 10 - 15 pints of blood.  Blood makes up about 10 percent of one's body weight. 
 
Blood can both give life and take it away.  Consider the history of blood transfusions. A transfusion means  taking blood from one living thing and injecting it into the bloodstream of another.  In the 1660's, several scientist experimented with it.  Richard Lower transfused blood between dogs with some success.  Then he injected lamb blood into humans.  A patient died.  Blood transfusion was outlawed. 
 
In 1818, James Blundell gave a women blood from her husband- no problem. But other patients died from transfusions.  Decades later, a German named Leonard Landois learned why blood mixing can be fatal:  Sometimes it makes red blood cells clump and explode.
 
In 1901, American bilogist Karl Landsteiner found the reason.  Some blood has antigens called A and B. (Antigens are special markers on germs and other substances that cause your body to make antibodies, proteins that defend against invaders.) These antigens are harmful to blood that doesn't have A or B antigens.
 
Today, doctors test blood for antigens BEFORE doing a transfusion.  Safe transfusions save countless lives.
 
 
 
All Blood Is Not Created Equal
Blood types include A, B, AB, and O.  The letters stand for two antigens (substances on germs that cause the body to make antibodies) labeled A and B. Type A blood has only the A antigenType B has the B antigenType AB has both.  Type O has neither.
 
 
Which A, B, and O types can safely mix?
 
Type A can donate only to someone who has the A antigen.
 
Type B can donate only to someone who has the B antigen.
 
Type AB can donate only to someone who has both the A and B antigens.
 
Type O has neither antigen and can safely donate to anyone.  Type O is called the "universal donor".
 
 
 

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Check for understanding:
Which blood type is the "universal recipient'?
Which blood type can recieve blood only from someone with the same blood type?
 
 
 
 
 
 
 
What happens if you get a blood transfusion with the wrong blood type? Even though a patient's own blood type is the first choice for blood transfusions, it's not always available at the blood bank. Try to save some patients' lives and learn about human blood types!
 
 
 
 
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