<prompt> Which of the following organs is not involved in calcium homeostasis?KidneysSkinIntestinesLungs  <response>: Ca2 homeostasis is achieved by 3 hormones: PTH, calcitonin, and vit. D. Ca2 levels are regulated from 3 tissues: bone, intestine, and kidneys. Skin has the precursor for vit. D synthesis. Vitamin D is involved in Ca2 absorption from G.I.T. 