Parathyroid hormone (pth) and calcitriol (the active form of vitamin d) to ensure enough calcium in the blood.
calcitriol does so by making sure enough ca2+ is absorbed from the diet. in order for ca2+ to be absorbed, cells lining the small intestine need ca2+ transporters. calcitriol is a steroid hormone.
1. propose a mechanism for how calcitriol works to increase ca2+ absorption from the diet.
one way that pth works is by ensuring kidneys don't allow ca2+ to leave via urine. in order to do this, kidney cells need ca2+ transporters. pth is a peptide.
2. propose a mechanism for how pth works at kidney cells. (hint: pth uses the camp system)
3. when you take vitamin d as a supplement, it is in the form of inactive vitamin d3. given all of this, does it matter if you take v-d and calcium at the same time? explain.