Blood is made up of four components - red blood cells, platelets, plasma, and white blood cells.

Red Blood Cells carry oxygen from the lungs to the body’s cells and bring carbon dioxide back to the lungs to be exhaled. Red blood cells are the most commonly transfused component and are used by accident victims, people receiving chemotherapy treatments, patients with ulcers and patients undergoing surgery. Platelets are cells that control bleeding by helping the blood clotting process. They are most commonly used to help patients receiving treatment for various cancers like leukemia. Plasma is the liquid portion of the blood, which transports water and nutrients to the rest of the body. It makes up about 55 percent of the total blood volume, and is used to treat clotting disorders, burn victims and shock. White Blood Cells protect the body against infection and disease, fight bacteria and help the body develop immunity to disease.

Why is blood separated?

Different patients need different types of blood components, depending on their illness or injury. After you donate whole blood, the unit is separated into red cells and plasma in our laboratory. One apheresis platelet donation provides enough platelets for one complete transfusion – that’s six times the amount collected from a whole blood donation.

How long does blood last?

Each blood component has a different "shelf life."

Platelets need to be stored at room temperature and must be kept in constant motion to prevent them from clumping before they are transfused into a patient. Platelets have a shelf life of only 5 days.

Red blood cells need to be stored in refrigeration and have a shelf life of 42 days.

Plasma is frozen and can be stored for up to a year. Once a unit of plasma is thawed, it must be transfused within 24 hours.

How much blood do I have in my body?

An average adult has between 10 and 12 units (pints) of blood or 2 units for every 25 pounds of body weight.

What is the Universal blood type?

Type O negative, occurring in about 9% of the U.S. population, is the Universal Donor and can be given to any other blood type. Type AB positive, which occurs in about 3% of the U.S. population, is the Universal Recipient and can receive blood from any other blood type.



The Blood and Tissue Center invites you to visit the Puget Sound Blood Center website for an interactive, graphically rich educational presentation about blood and hematology, the study of blood. Also interesting is the History of Blood Transfusion.