Bone marrow is the flexible tissue found in the interior of bones. In humans, red blood cells are produced in the heads of long bones, in a process known as hematopoesis. On average, bone marrow constitutes 4% of the total body mass of humans; in an adult weighing 65 kilograms (140 lb), bone marrow accounts for approximately 2.6 kilograms (5.7 lb). The hematopoietic compartment of bone marrow produces approximately 500 billion blood cells per day, which use the bone marrow vasculature as a conduit to the body's systemic circulation. Bone marrow is also a key component of the lymphatic system, producing the lymphocytes that support the body's immune system.
Famous quotes containing the words bone and/or marrow:
“Two wooden tubs of blue hydrangeas stand at the foot of the stone steps.
The sky is a blue gum streaked with rose. The trees are black.
The grackles crack their throats of bone in the smooth air.
Moisture and heat have swollen the garden into a slum of bloom.
Pardie! Summer is like a fat beast, sleepy in mildew....”
—Wallace Stevens (18791955)
“Our hearts seemed safe in our breasts and sang to the
The marrow in the bone
We dreamed was safe . . . the blood in the veins, the
sap in the tree
Were springs of Deity.”
—Dame Edith Sitwell (18871964)