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Why do our bones atrophy without gravity?
Muscles I understand- but why bones?
Related- spend long enough time in space, would every part of our bodies go bad? Eyesight and hearing too?
How about our minds with the thinking stuff we do? Would those synaptic connections weaken or stop working?
- 1 month ago
Bone density is dependent on stress. So if your bones are subject to lots of stress, e.g., during exercise you will have high bone density. When not subjected to as much gravity as on Earth bones do not suffer very much stress.
Bone tissue is constantly being made and broken down. Its density depends on which is happening at a greater rate. Bone synthesis happens at a greater rate under stress. When there is little stress breakdown is greater and density is lost.
- SciencenutLv 71 month ago
I am an MD. As I was taught, our bones are being continuously recycled throughout our lifetimes. Furthermore, bone mineralization is being constantly adjusted throughout our lives based on needs, which for bones, means stress, including the stress of bearing weight. If there is little or no stress, then the bone mineral density tends to diminish, since the need is absent. And for instance, fat people tend to have strong, dense bones, while skinny little old ladies tend to have almost no bone density, causing them to be easily prone to bone fractures.
And as a general principle, anything in the body that is less used will tend to undergo atrophy.
- ?Lv 61 month ago
Bones evolved to support weight. If they no longer need to do so, the body harvests their inventory of calcium and other minerals, leading to the bones weakening.
Similarly minds evolved to be stimulated. Spending months or years drifting through the sheer utter boredom of outer space causes the brain to shrink to the size of a pea, although to be daft enough to be suckered into such a misadventure in the first place suggests a certain amount of atrophy to begin with.