Biology / Unit 13 Bio 3095 short lesson, about 20 seconds
Bone Marrow: Red and Yellow
Captions available
The idea
Red bone marrow produces blood cells inside spongy bone cavities, while yellow bone marrow stores fat and gradually replaces red marrow in many bones with age.
In practice
An adult's red marrow concentrates in flat bones like the sternum, while long-bone shafts hold mostly yellow marrow.
Where people slip
Yellow marrow can revert to blood-cell production under severe demand — the two types are not fixed permanently.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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