osteoporosis

Topics: Bone, Osteoporosis, Vitamin D Pages: 7 (1832 words) Published: April 27, 2014
Miti Rupani

Assignment #5
Question: What causes osteoporosis? Will many tips that the media sells people for osteoporosis actually helps increase bone density? Claim: Several factors cause osteoporosis such as gender, age, body size, genetic history and lifestyle choices. The tips that media sources publicize will actually help prevent bone mass loss and in the long run, prevent osteoporosis.

Background:

What is osteoporosis?

Osteo comes from the Greek word osteon meaning “bone” while “porosis” comes from the poros meaning “hole passage.” In medical terms, osteoporosis means a chronic disease that causes reduction in the quantity of bone or atrophy of skeletal tissue; age-related disorder characterized by decreased bone mass and loss of normal skeletal microarchitecture, leading to increased susceptibility to fractures. It is the most common disease in humans affecting both sexes and all races. The disease often has no early warning signs, and an individual may not know that he or she has osteoporosis until a fracture occurs in a situation in which a normal person would normally not break a bone. The absence of signs or symptoms makes this disease so difficult to diagnose and hence, treat.

Evidence and Reasoning:

Bone structure and Osteoporosis

In the above picture, it is shown how a normal bone’s structure differs from a bone that has undergone deterioration from osteoporosis. Bone is made up of trabecular bone (spongy marrow found at the end of the long bones) and the denser cortical bone that forms the outside of the bone. The formation of the bone involves 2 processes known as modeling and remodeling. During childhood and adolescence, modeling allows for the formation of new bone in 1 area and removal of old bone in another. Following puberty and during adulthood, the process shifts to remodeling, where the existing bones are reabsorbed and replaced. However, there is no increase in the amount of bone. On the cellular level, there are two kinds of cells involved in bone modeling and remodeling. These two cells are called osteoblasts and osteoclasts. Osteoblasts are responsible for laying down new bone in areas where osteoclasts have created a cavity by resorption of older bone. The process continues until the cavity is filled. A protein called osteoprotegerin that binds to osteoprotegerin-ligand controls bone resorption and growth through this whole process. Osteoporosis results when there in an imbalance between osteoclast and osteoblast activity, resulting in bone that is fragile due to a decrease in bone mass and density. The rapid loss of trabecular bone accompanied by a slower loss of cortical bone puts the individual at risk for fractures. The spine (vertebra) and hipbones have a higher ratio of trabecular bone and, therefore, are at a greater risk of fracture. This is also why the BMD of these bones is most often used in diagnosing osteoporosis.

Hormones and Osteoporosis

Three hormones play a significant role in bone development; parathyroid hormone (PTH), calcitonin and hormonal vitamin D. Parathyroid hormone speeds up bone breakdown, and calcitonin acts to conserve calcium, which blocks the effects of PTH. Parathyroid hormone also acts to increase the level of calcium in the body by increasing the production of activated vitamin D, which in turn increases the intestinal absorption of calcium. Vitamin D is produced in skin tissues during exposure to the sun’s ultraviolet rays. The body works to maintain a constant level of calcium in the blood, and if there is interference with the hormonal feedback process, it results in a decrease in bone quality and strength.

Other risk factors for Osteoporosis

In this graph, it is shown how osteoporosis affects men and women contrarily and how the specific kinds of bones that are affected by osteoporosis differ in both the groups.

Other than bone structure malfunction and endocrinal hormone shortage or surplus, quite...
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