1. Describe bone physiology and the bone remodeling cycle. Be sure to emphasize the two types of bone tissue and the roles of osteoblasts and osteoclasts.
During our adolescent years our bones are evolving to become protracted and broader. Therefore, formation is occurring until we have reached our peak bone mass. The peak bone mass is usually reached by the age of 30; therefore, as we age formation decelerates. Essentially, exercising is an ethical verdict, especially during our matured years.
One of the key elements of regulating skeletal growth is the Osteoclasts. The Osteoclasts are responsible for initiating the bone remodeling cycle. Blood vessels and nerves are able to penetrate the bone once the chondrocytes die allowing Osteoblasts to secret osteoid; this is a protein fiber, into the cavities created by the Osteoclasts. Once the osteoblasts become trapped in the cavities they turn into osteocytes, thus creating spongy bone forms. Then Osteoblasts build compact bone around the already formed spongy bone by secreting their matrix. In conclusion, the osteoclasts digest old bone and the osteoblasts lay down new bone. (describe steps in building bone and talk about spongy bone and compact bone)
- Resorption- osteoclasts digest old bone
- Reversal- when mononuclear cells appear on the bone surface
- Formation- when osteoblasts lay down new bone until the resorbed bone is completely replaced.
Fractures due to the strain caused by repetitive exercise. They are thought to arise from a combination of MUSCLE FATIGUE and bone failure, and occur in situations where BONE REMODELING predominates over repair. The most common sites of stress fractures are the METATARSUS; FIBULA; TIBIA; and FEMORAL NECK.
- http://www.ncbi.nlm.nih.gov/pubmed/17308163
The continuous turnover of bone matrix and mineral that involves first, an increase in resorption (osteoclastic activity) and later, reactive bone formation (osteoblastic activity). The process of bone remodeling takes place in the adult skeleton at discrete foci. The process ensures the mechanical integrity of the skeleton throughout life and plays an important role in calcium homeostasis. An imbalance in the regulation of bone remodeling’s two contrasting events, bone resorption and bone formation, results in many of the metabolic bone diseases, such as OSTEOPOROSIS. Year introduced: 1992
2. Explain the relationship between calcium and bones.
The bones are made up of two minerals, including calcium. Calcium is critical in order to maintain the level of bone mass to support structures of the body. If calcium is truncated in other regions of the body then it will be released from the bones into the bloodstream sending it to the appropriate destination. Bones begin to weaken if an insufficient amount of calcium is not consumed. The body will discontinue absorbing calcium if an abundant amount of calcium is consumed, in which vitamin D aids this process.
3. Explain how the body controls calcium levels in the bones and blood. Be sure to describe the roles of parathyroid hormone (PTH) and calcitonin in detail. According to National Institutes of Health, 99% of calcium is stored in our teeth and bones. Some of our organs require calcium for certain process, such as muscle contraction; therefore, the remaining one percent remains in our blood. The blood and bones regulates calcium levels by the means of hormones. Two of the main systematic modifiers are Calcitonin and the Parathyroid hormone. Calcitonin and the Parathyroid hormone both influence the calcium concentration in the blood. While calcitonin depresses the calcium levels in the blood it also impedes the parathyroid hormone. Calcitonin is practical only in the bones. In the bones calcitonin inhibits the osteoclast activity, thus hindering bone loss. In contrast, the parathyroid hormone increases the calcium levels in the blood.
4. Explain specifically how osteoporosis affects the bone matrix and the normal bone remodeling cycle.
If resorbtion or formation of the bone is impaired then the individual will be suffering from the disease dubbed Osteoporosis. Two subsequent effects can occur if an individual has Osteoporosis. Either resorbtion occurs at a faster rate than formation, or vice versa. A deficiency of bone deposit results from a lack of calcium and vitamin D.
- http://ic.galegroup.com.ezp.tccd.edu/ic/suic/ReferenceDetailsPage/ReferenceDetailsWindow?failOverType=&query=&prodId=SUIC&windowstate=normal&contentModules=&mode=view&displayGroupName=Reference&limiter=&u=txshracd2560&currPage=&disableHighlighting=false&displayGroups=&sortBy=&source=&search_within_results=&p=SUIC&action=e&catId=&activityType=&scanId=&documentId=GALE%7CA79513488
- http://ic.galegroup.com.ezp.tccd.edu/ic/suic/ReferenceDetailsPage/ReferenceDetailsWindow?failOverType=&query=&prodId=SUIC&windowstate=normal&contentModules=&mode=view&displayGroupName=Reference&limiter=&u=txshracd2560&currPage=&disableHighlighting=false&displayGroups=&sortBy=&source=&search_within_results=&p=SUIC&action=e&catId=&activityType=&scanId=&documentId=GALE%7CA16694001
- Heinz, Agnes. “Osteoporosis.” Pamphlet by: American Council on Science and Health. American Council on Science and Health, 1992. 1+. Student Resources in Context. Web. 14 Nov. 2013
- “Osteoporosis Overview.” Pamphlet by: National Institutes of Health. National Institutes of Health, 2000. 1. Student Resources in Context. Web. 13 Nov. 2013.