The essential functions of bone marrow range from creating cartilage, bone, and fat to providing the basis for the immune system. Bone marrow creates blood cells and platelets. White blood cells fight infection, red blood cells carry oxygen, and platelets are responsible for blood clotting. The body produces approximately 200 billion new blood cells every day. Marrow has an essential role in growth, fighting infection, and keeping sufficient amounts of oxygen in tissues and organs. Babies are born with almost entirely red bone marrow to support the rapid growth in the first years of life; yellow marrow develops with age. The body can convert yellow marrow back to red marrow to increase blood cell production in adults if oxygen levels in tissues severely decrease.


1. Structure

It is a soft, gelatinous tissue inside the bones. The two types of bone marrow are myeloid tissue or red bone marrow and fatty tissue or yellow bone marrow. Capillaries and other blood vessels fill both types. Red marrow is usually present in the breast bone, skull, ribs, vertebrae, hip bones, shoulder blades, and the ends of long bones. Yellow marrow exists in the cavities of long bones.

structure bone marrow

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