Blood Facts
Blood Components
Whole blood is compromised of four main components: plasma, red cells, white cells, and platelets.
Plasma is a pale yellow mixture of water, protein, and salts. One of its primary functions is to carry blood cells, nutrients, enzymes, hormones, certain gases, and waste products.
Red cells are disc-shaped cells containing hemoglobin, a red protein that contains iron. Hemoglobin enables the cells to pick up and deliver oxygen to all parts of the body. Red cells also take carbon dioxide to the lungs, where it is exhaled.
White cells are the body's primary defense against infection. They have the ability to move out of the blood stream and reach tissue being invaded.
Platelets are small blood cells that control bleeding. They form clusters to plug holes in blood vessels and assist in the clotting process when the vessels are severely damaged.
Blood Types
There are four blood types: A, B, AB, and O. The approximate distribution of blood types in the U.S. are as follows (distribution may be different for specific racial and ethnic groups):
- O+38%
- O-7%
- A+34%
- A-6%
- B+9%
- B-2%
- AB+3%
- AB-1%
People with type O negative blood are known as universal donors, and those with type AB positive blood are known as universal recipients.
Did You Know?
- There is no substitute for human blood. It can only come as a gift from people.
- About 1 in 7 people entering a hospital need blood.
- One pint of blood can save up to three lives. One unit is divided into three parts: red blood cells, platelets, and plasma.
- If all blood donors donated two to four times a year, it will help prevent blood shortages.
- 40,000 pints of donated blood are used each day in the U.S.
- The average transfusion patient receives 3 units of red blood cells.
- 4.5 million Americans would die each year without life-saving blood transfusions.
- Every 2 seconds someone needs blood.
Those in Need
Car accident victims who have suffered massive blood loss can require red blood cell transfusions of 50 units or more.
The average bone marrow transplant patient requires 120 units of blood platelets and approximately 20 units of red blood cells.
Severe burn victims require approximately 20 units of plasma during their treatment.
Anemic patients need blood transfusions to increase their red cell count.
Cancer, transplant, trauma patients and patients undergoing open heart surgery require blood platelet transfusions to survive.
Some patients with complications from severe sickle cell disease, an inherited disease that affects more than 80,000 people in the U.S. (98% of whom are of African-American descent), may receive blood transfusions every month - up to four units at a time.
