Calcium homeostasis is maintained by all except

Ans: b (lung)Ref: Ganong, 22nd ed. Pg. 392Kidney, liver and skin is related to the production of vitamin D in the body, so these are involved in calcium haemostasis. Hormones related to calcium metabolism and their effectParathormone (PTH)-Increase in PTH causes increase bone resorptionIncrease renal reabsorption of calcium, "!reabsorption of phosphatesIncrease Intestinal absorption of calcium through vitamin DOverall effect -- increased S. calcium, decreased S. phosphate.Calcitonin-increase in calcitonin causes- Increase bone mineralization Increase renal excretion-proximal tubule Decrease bone resorptionVitamin D-increased in vitamin D causes:Increase Intestinal reabsorption of calcium through Calbindin D 28K.Increase bone resorption by osteoclastic activity Increase renal reabsorption in proximal tubule of both calcium and phosphates Overall effects-Increase in S. calcium, and increase in S. phosphatesEffects of Hormones on bonePTH - Increase osteoclast, Increase osteoblast Vitamin D - Increase osteoclast, Increase osteoblastCalcitonin - Decrease osteoclast, osteoblast no changeRememberPTH has no direct action on Intestine, but acts through vitamin D Vitamin D augments the action of PTH in kidneyRANKL is seen on the osteoblast and RANK on osteoclastOPG (osteoprotegerin) - inhibitor of RANKL Osteoblastic transducing signal - cbfal