Explain how the body maintains homeostasis with regard to

Question

1. Explain how the body maintains homeostasis with regard to blood calcium levels. What does the body do if the blood calcium levels are too LOW? How does it detect this and how does it respond (identify and discuss the stimulus, receptors, control center and all of the effectors involved)? What does the integument have to do with all of this? Be sure to describe all of the hormones involved in this homeostatic mechanism.
2. If a tumor was to develop in the parathyroid gland, how would that affect blood calcium levels?
3.  Why is a compound fracture more serious than a simple fracture (other than broken skin)? How can you tell the difference (anatomy- and physiology-wise) between a stress and a pathologic fracture?
4. Why is a cast needed for proper healing of a bone fracture? At what point in the fracture healing process is the bone most vulnerable? When does it start to become less vulnerable?
5.  Explain how one could prevent osteoporosis through the proper diet (what would need to be consumed?) and exercise. Why is diet and exercise important for healthy bones?