In postmenopausal osteoporosis, decreased estrogen levels lead to increased bone resorption.

在绝经后质疏松中，雌激素的少引发了吸的加。

As a result, bone deposition decreases due to a lack of stress, while resorption increases.

由于缺少应力的作用，骼沉积少，同时骼吸。

So, bone resorption usually overtakes bone formation around the 8th decade of life.

因此，人到80岁之后，吸能力通常压制生长能力。

Finally, vitamin D promotes calcium absorption in the gut, so it increases serum calcium, promoting bone formation and decreasing bone resorption.

最后，维生素D促进钙在肠内的吸，因此加了血清钙的水平，促进生长并弱吸。

Over time, this resorption of calcium from the bones leaves them weak and brittle, a condition known as renal osteodystrophy.

随着时间推移，这种溶生钙的过程导致变得脆弱易碎，这就是肾性营养不良。

Alright, as a quick recap, osteoporosis refers to decreased bone density, on account of increased bone resorption compared to bone formation.

好！快速回顾一下：质疏松意味着的降低，由自身吸能力大于生长能力造成。

Parathyroid hormone is produced by the parathyroid glands in response to low serum calcium, and it increases bone resorption to release calcium into the bloodstream.

顾名思义，甲状旁腺激素在甲状旁腺产生，来应对血清中过低的钙水平，从而加质的吸来释放更多的钙进入血液。

Now, even though parathyroid hormone stimulates bone resorption, it's been found that intermittent injections with teriparatide activates osteoblasts more than osteoclasts, therefore increasing bone formation.

其实，即使甲状旁腺激素刺激吸，研究发现间歇性注射特立帕肽激活了更多造细胞而非破细胞，从而生长。

This is caused by increased bone resorption, which is a process that breaks bones down, eventually fast enough that it outweighs the rate of new bone growth.

这是由骼逐渐溶蚀所引起，整个过程会造成折，最终则因速太快，远超过骼的生长率。

Parathyroid hormone is secreted in response to low blood calcium levels, and it stimulates the resorption of calcium and a small amount of phosphate from the bone and into the bloodstream.

在血钙降低时，甲状旁腺激素分泌加，刺激钙的重吸，并且使一小部分磷酸盐从中入血。

But, for reasons that we don't understand yet, the osteoclasts actually increase their rate of bone resorption in low gravity, while the osteoblasts dial back on the bone formation.

但是，由于我们还不明白的原因，破细胞实际上在低重力下加了吸的速，而成细胞则少了的形成。

On the other hand, calcitonin is produced by the thyroid gland in response to high serum calcium, so it opposes the action of PTH - therefore promoting bone formation and decreasing bone resorption.

另一方面，当血清中钙含量较高时，甲状腺释放降血钙素，来制约甲状旁腺激素的作用，从而促进骼的形成并缓骼的吸。

When they get there, they secrete both a collagen-digesting enzyme, and an acidic hydrogen-ion mixture that dissolves the calcium phosphate, releasing its components back into the blood. This tear-down process is called resorption.

当它们到达那里时，它们会分泌胶原蛋白消化酶和酸性氢离子混合物，溶解磷酸钙，将其成分释放回血液中。这种撕裂过程被称为吸。