MICROANATOMY

Detailed explanation-1: -This hormone raises calcium levels by releasing calcium from your bones, increasing the amount of calcium absorbed from your small intestine and decreasing the amount of calcium lost in urine. When blood-calcium levels are too high, the parathyroid glands produce less parathyroid hormone.

Detailed explanation-2: -At the bone, PTH inhibits osteoblast activity and stimulates osteoclast activity leading to bone breakdown and calcium release. At the kidneys, PTH increases calcium reabsorption and blocks phosphate reabsorption from the tubules. PTH also acts at the kidneys to stimulate the formation of vitamin D.

Detailed explanation-3: -Calcium homeostasis is maintained by actions of hormones that regulate calcium transport in the gut, kidneys, and bone. The 3 primary hormones are parathyroid hormone (PTH) 1, 25-dihydroxyvitamin D-3 (Vitamin D3), and calcitonin.

Detailed explanation-4: -Figure 37.9. 1: Regulation of blood calcium levels: Parathyroid hormone (PTH) is released in response to low blood calcium levels. It increases blood calcium levels by stimulating the resorption of bones, increasing calcium resorption in the kidneys, and indirectly increasing calcium absorption in the intestines.