What Bone Marrow Is, The Two Types Of Bone Marrow, & Why They Are Important To The Body

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3. What is bone marrow? What two types of bone marrow exist, and why are they important to the overall health of the body?

We think of our bones simply as hard mineral structures that give our bodies a frame. In fact, our bones aren’t only a matrix of calcium, phosphorus, and collagen. Our bones also contain thousands of living cells and nerves inside of them. This is why we feel pain when our bones get broken or damaged. Long and flat bones, such as our ribs, hips, femur and shoulders, all contain bone marrow internally. This bone marrow comes in two different types.

Red marrow creates blood cells and stem cells. This includes osteoblasts, “immature” bone cells which secrete osseous material and the mineral matrix. The “mature” osteocytes, secrete bone growth hormones during childhood and bone maintenance hormones during adulthood. The counterpart of red marrow is yellow marrow. These are mostly fat cells which support the function of the red marrow. It is interesting to note that newborns do not have any yellow marrow; the child’s bones begin producing it only when the child begins to mature. Once a human reaches adulthood, his bones contain equal amounts of both variations of marrow.

Red and yellow marrow are part of the trabecular bone, which is spongy inside. This is the part of the bone that contains most of the living cells as opposed to the cortical or compact bone. Which contains mostly the mineral matrix. An easy way to remember the functions of these two different marrows is to associate red marrow with blood, and yellow marrow with fat.

Lesson 170, Biology @zbelles