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What is the blood composition? What are white blood cells, red blood cells , platelets and their specific function?

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Blood is composed of plasma, red blood cells, white blood cells, and platelets. Blood cells are made by bone marrow.

Plasma is a straw colored substance that is approximately 90% water. It suspends the cells.

There are more red blood cells (erythrocytes) than any other type of cell. Red blood cells never divide. About 3 million red blood cells die and are scavenged by the liver each second. Red blood cells are responsible for transporting oxygen and carbon dioxide.

White blood cells are called leukocytes. There are a lot less white blood cells than red blood cells (1:700). They play a major role in fighting infection. There are many different types of white blood cells that each perform a very specific function. These cells are called monocytes, neutrophils, eosinophils, and basophils.

Platelets are controlled by a homeostatic mechanism. They play a major role in clotting. When coagulation occurs (blood clot) it forms a plug of platelets. Platelets are cell fragments formed by megakaryocytes.

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