Final answer:
Other factors that affect PTH in bone metabolism include calcitonin, which inhibits osteoclasts, and growth hormone, thyroid hormone, and sex hormones which stimulate osteoblast activity. PTH itself stimulates osteoclasts, affects calcium reabsorption in the kidneys, and activates vitamin D to increase intestinal absorption of calcium.
Step-by-step explanation:
Other Receptors/Enzymes Affecting PTH in Bone Metabolism:
In addition to PTH (parathyroid hormone), there are other receptors and enzymes that play significant roles in bone metabolism. Calcitonin, a hormone from the thyroid gland, acts in opposition to PTH by inhibiting osteoclast activity, thereby reducing calcium levels in the blood and promoting calcium uptake by bones. Furthermore, the rate at which osteoblasts form new bone is influenced by growth hormone, thyroid hormone, and sex hormones (estrogens and androgens).
To regulate the correct balance of calcium, PTH stimulates osteoclast activity which releases calcium into the bloodstream when blood calcium levels are low. It also affects the kidneys, increasing reabsorption of calcium to prevent its loss through urine. Moreover, PTH promotes the conversion of vitamin D into its active form, calcitriol, which is crucial for calcium absorption in the intestine.
These hormones and enzymes work together to maintain calcium homeostasis, with their activities being finely tuned by feedback mechanisms responding to the calcium levels in the blood.