About Blood

Blood Components

What is blood made of?

Think of your blood as a fruit smoothie made up of about four basic ingredients blended together, all of them important:

  • Red Blood Cells
  • White Blood Cells 
  • Platelets
  • Plasma

Blood cells are produced in the marrow of bones, especially the vertebrae, ribs, hips, skull and sternum. A unique cell, the stem cell, is the "parent of all cells." These essential blood cells fight infection, carry oxygen and help control bleeding.

Blood _parts _vial
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Red Blood Cells - (erythrocytes)

Red blood cells are disc-shaped cells containing hemoglobin, which enables the cells to pick up and deliver oxygen to all parts of the body, then pick up carbon dioxide and remove it from tissues.

  • Make up about 40 percent of your blood.
  • Carry oxygen from the lungs to tissue, and carry back carbon dioxide to the lungs.
  • Contain the molecule hemoglobin which carries the oxygen and makes blood red.
  • Live about 120 days and are removed by the spleen.
  • Have an after-donation shelf life of 35-42 days.
  • Most needed for patients with significant blood loss through trauma, surgery, or anemia.
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White Blood Cells - (leukocytes)

White cells are the body's primary defense against infection. They can move out of the blood stream and reach tissues being invaded by microbes and foreign bodies.

  • There are several different types of white blood cells.  Lymphocytes are key parts of our immune system and help our bodies fight infection.
  • There are two types of lymphocytes: T cells direct the activity of the immune system; B lymphocytes produce antibodies which destroy foreign bodies.
  • White blood cells may themselves harbor infectious disease and some pathogens are more concentrated in them than other blood products. Leukoreduction is the process of removing white blood cells from blood supplied for transfusion. 
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Platelets - (thrombocytes)

Platelets are very small colorless cell fragments in your blood whose main function is to stop bleeding.  

  • They are the sticky cells that clump together to form clots that control bleeding by sticking to the lining of blood vessels.
  • When exposed to air a chemical reaction causes a protein in the blood, called fibrinogen, to turn into long threads which form a scab over the wound.
  • Survive in the circulatory system for about 10 days and are removed by the spleen.
  • Outside the body they can be stored for only five days.
  • Used to help patients with malignant diseases who have low or abnormal platelets due to the disease itself or chemotherapy. Platelets are in high demand for people with leukemia, blood disorders, cancer; recipients of bone marrow or organ transplants and accident, burn, and trauma victims. 
  • An average of four to eight units of platelets from whole blood donations (or one apheresis donation) is needed to meet one patient's needs.
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Plasma is a pale yellow mixture of water, proteins and salts. One of the functions of plasma is to act as a carrier for blood cells, nutrients, enzymes, and hormones.

  • This is the liquid portion of the blood. Plasma is 90 percent water and makes up more than half of total blood volume.
  • Other 10 percent is protein molecules, including enzymes, clotting agents, immune system components, plus other body essentials such as vitamins and hormones.
  • Helps to maintain blood pressure and keeps everything moving through the circulatory system, supplying critical proteins and serving as an exchange system for vital minerals.
  • Plasma is frozen after collection and can be stored up to one year.
  • Used to treat bleeding disorders when clotting factors are missing; plasma exchanges remove disease-causing factors from patient's plasma.
  • Used to extract cryoprecipitate, a substance rich in Factor VIII, which is needed by hemophilia patients.
  • Plasma purchased at for-profit centers is sold for research and some medical therapies.