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Red cells, white cells, and platelets are made in the marrow of bones, especially the vertebrae, ribs, hips, skull, and sternum. These essential blood cells fight infection, carry oxygen, and help control bleeding. |
More than half of blood is plasma. Plasma is the liquid portion of blood; a straw-colored liquid that is 90 percent water and constitutes 55 percent of a humans' blood volume. The remaining ten percent of plasma contains more than 200 substances including proteins, vitamins, sugar, fats, and minerals that fight disease and act as chemical messengers.
Plasma is the circulating liquid in which red and white cells, as well as platelets, move. It carries nutrients to all parts of the body and carries off waste products. It helps to maintain blood pressure and blood volume, and supplies proteins for blood clotting and immunity.
The average adult body contains about 10-11 pints of blood, of which six pints are plasma.
Red Blood Cells give your blood its color. The red color comes from a combination of oxygen and hemoglobin, which consists of iron containing protein. The hemoglobin makes it possible for red blood cells to pick up oxygen from the air you breathe and to carry that oxygen from your lungs to the trillions of cells that make up your body.
The oxygen released by the red cells helps convert nutrients in foods such as milk, red meat, and green vegetables into energy. As each red blood cell distributes its load of oxygen to the cells, it picks up carbon dioxide and carries it back to lungs to be exhaled.
Red Blood Cells are round and tiny, about 3,000 end-to-end would equal once inch. An average adult's body contains about 25 trillion red blood cells, approximately 600 times the number of white cells. Red blood cells live approximately 120 days in the circulatory system.
An average adult’s body normally contains over 35 billion white cells –one for every 600 red cells.
Photo Copyright: Dennis Kunkel, University of Hawaii |
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White Blood Cells are important to your body in several ways:
- They protect the body from invasion by bacteria, fungi, and viruses.
- They keep you from catching the same viral diseases over and over again.
- They “eat” harmful bacteria, the kind you would have in a cut, scraped knee or in an infected ear.
Platelets are very small and irregularly shaped particles in the blood. When you get a scratch or cut that bleeds, it means that some blood vessel has been cut or broken. In the blood, near the cut, platelets adhere to the lining of the blood vessels. They pile together at the injury site, sticking to each other to slow the flow of blood.
As more platelets gather, some break up and release chemicals which form a web of fibrin threads. Red and white blood cells get caught in the web of fibrin, making the plug grow bigger and more solid. Finally it is a firm clot that stops the flow of blood.
Platelets survive in the circulatory system for an average of 9-10 days before being removed by the spleen.
- Every three seconds someone needs blood.
- One out of every seven people entering a hospital needs blood.
- Approximately 38,000 units of blood are used each day in the United States.
- The average male adult has about 12 pints and females have about nine pints of blood in circulation.
- There are four main blood types: A, B, AB, and O.
- One unit of blood can be separated into several components (red blood cells, plasma, platelets and cryoprecipitate).
- Red blood cells are made in the bone marrow and transport oxygen to body tissue. The body replaces red blood cells approximately two to three weeks after donation. Refrigerated red cells have an expiration date of 42 days.
- Plasma makes up 55% of blood volume and transports blood cells, clotting factors, nutrients, and antibodies. The body replaces plasma within 24 hours of donation. Frozen plasma can be stored up to one year.
- Platelets are made in the bone marrow. The body replaces platelets within 72 hours of donation. Platelets are always in demand as they have a shelf life of five days.
- People who have been in car accidents and suffered massive blood loss need transfusions to recover. Anemic patients need blood transfusions to increase their iron levels.
- Cancer, transplant and trauma patients, and patients undergoing open-heart surgery may require platelet transfusions to survive. Severe burn victims often require multiple units of platelets during their treatment.
- Apheresis is a special kind of blood donation that allows a donor to donate specific blood components through the use of automated equipment.
- 37% of the US population is eligible to donate – only 5% of those eligible donate regularly.
- There is no substitute for human blood.
- Whole blood can be safely donated every 8 weeks.
- Blood makes up approximately 7% of your body's weight.
- If you began donating at age 16 (with parental permission) and donated every 56 days until you reached age 76, you would have donated over 45 gallons of blood.
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