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

在绝经后骨质疏松中，雌激素的减少引发了骨吸收的增加。

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

由于缺少应力的作用，骨骼沉积减少，同时骨骼吸收增强。

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

因此，人到80岁之后，骨吸收能力通常压制骨生长能力。

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促进钙在肠内的吸收，因此增加了血清钙的水平，促进骨生长并减弱骨吸收。

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，这种溶骨生钙的过程导致骨变得脆弱易碎，这就是肾性骨营养不良。

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：骨质疏松意味着骨密度的降低，由自身骨吸收能力大于骨生长能力造成。

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，从而增加骨质的吸收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骨吸收，研究发现间歇性注射特立帕肽激活了更多造骨细胞而非破骨细胞，从而增强骨生长。

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.

这是由骨骼逐渐溶蚀所引起，整个过程会造成骨折，最终则因速度太快，远超过骨骼的生长率。

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，甲状旁腺激素分泌增加，刺激钙的重吸收，并且使一小部分磷酸盐从骨中入血。