Grades 6–8 · Organisms
How can the inside of a bone help replace blood cells?
Bone is more than a hard supporting material. Inside some bones, red bone marrow contains stem cells that help produce the components of blood. These include red blood cells, many white blood cells and platelet-forming cells.
In the diagramMarrow supplies several blood componentsblood-forming stem cellred blood cellwhite-cell branchlarge precursorplatelet fragments
A blood-forming stem cell can divide while maintaining a supply of stem cells. Some descendants enter developmental paths that lead to specialized cells. Different signals influence which paths are followed and how much production occurs.
Developing red blood cells acquire large amounts of hemoglobin for carrying oxygen. White blood cells have varied immune functions. Large marrow cells called megakaryocytes release small fragments that become platelets, which help limit bleeding.
Blood components do not last forever, so replacement continues throughout life. Marrow production also responds to changing needs. This hidden tissue supports circulation by supplying working parts, rather than pumping blood or turning hard bone directly into blood.
About this explanation
Starting knowledge: Know that blood contains different components and that living cells can divide and specialize.
Sources
- National Heart, Lung, and Blood Institute — Your Guide to Anemia