Question

Pick one of the following questions to answer. Do not repeat answers that have already been stated. No credit will be given for repeated answers. DO NOT answer the question number in its entirety. Answer only what is being asked.

 1. Discuss one specific mechanism in which calcium or phosphate is regulated.

 2. Discuss one specific agent that affects bone metabolism.

 3. Discuss a bone disease that is covered in the powerpoints or textbook and treatment, if any.

 4. Discuss a bone fracture that is covered in the powerpoints or textbook and treatment, if any.

Answer 1

1. The primary mechanism by which calcium is regulated by the action of hormone PTH and vitamin D,  which act at bone, kidney, and GI tract to increase serum calcium and to a lesser extent calcitonin, which decreases bone resorption, but does not appear to have a major effect on serum calcium under normal circumstances. When blood calcium levels are low, The parathyroid hormone (PTH), secreted by the parathyroid glands stimulates the release of osteoclasts, which break down bone to release calcium into the blood stream, and than PTH increases blood calcium levels by increasing the amount of calcium resorbed by the kidneys before it can be excreted in the urine and in addition to this PTH triggers the formation of calcitrol, an active form of vitamin D, which act on the intstine to increase the absorption of dietary calcium, when calcium levels are low PTH release is inhibited.

2.The most important factor that affects bone metabolism is the activity of bone cells like, osteoclast and osteoblast, osteoclasts, which are the cells that resorb bone,while osteoblast are the cells that form bone, age, physical activity and diet can all affect the activity of these bone cells, for eg,  The prevalence of osteoporosis increases with age due to an imbalance in the rate at which bone is removed and replaced during the bone remodeling cycle.

3. Pagets disease, It is a disorder of the bone remodeling process, in which the body absorbs old bone and forms abnormal new bone. Over time, the disease can cause affected bones to become fragile and misshapen. Paget's disease of bone most commonly occurs in the pelvis, skull, spine and legs. The goal of treatment is to relieve bone pain and prevent the progression of the disease.Treatment involves medication that reduces the breakdown of bone.Some common medication include drugs like Bisphosphonates, calcitonin, in rare cases surgery might be done.

4.Stress fracture other wise known as hairline fracture, are caused by repetitive stress or force from overuse, most often tiny cracks on a bone develop in the foot or lower leg. It is common for hairline fractures to occur as a result of sports that involve repetitive jumping or running.These fractures may also occur in the upper limb and are often related to falls or accidents. As a part of tyreatment Your doctor may recommend that you use crutches to keep weight off an injured foot or leg. You can also wear protective footwear or a cast.