Blood Facts
Blood contains four main components:
- Red Cells - that help carry oxygen to tissues
- White Cells - that help the body fight disease and infection
- Platelets - that help prevent bleeding
- Plasma - that carries proteins and other clotting factors.
There are four major blood types: "O", "A", "B", and "AB". Also, a certain substance, the "Rh- factor, is either present on the red cells or absent.
Approximately 85% of the population has "Rh" factor on their red cells. These people are categorized as "Rh" positive. About 15% of the population lack the "Rh" factor making them "Rh" negative. The blood type breakdown in the United States is as follows:
| Blood Type | Number of People | % of Population |
| O pos | 1 in 3 | 37.4% |
| O neg | 1 in 15 | 6.6% |
| A pos | 1 in 3 | 35.7% |
| A neg | 1 in 16 | 6.3% |
| B pos | 1 in 12 | 8.5% |
| B neg | 1 in 67 | 1.5% |
| AB pos | 1 in 29 | 3.4% |
| AB neg | 1 in 167 | 0.6% |
The rarest type of blood is the type that is not available when a patient needs it.
It takes 24 to 72 hours to type and test blood after a donation and BEFORE it can be used for patient.
In a crisis, the blood that saves lives is the blood that was donated BEFORE the crisis!
How Much Blood Does a Person Have?
- A unit of blood is equal to one pint or two cups.
- For every 25 lbs. of body weight, you have two pints.
- A person weighing 125 lbs. has 10 pints of blood in circulation.
- A person weighing 150 lbs. has 12 pints of blood.
