Bone and Calcium Homeostasis
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Created by:
collfire90 on March 6, 2012
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21 terms
Terms | Definitions |
|---|---|
 Osteoid | the collage matrix that surrounds the other types of connective tissue in bones. Upon it are many deposited minerals, particularly the crystals of calcium phosphate and hydroxyl ions called hydroxypapitate |
| Osteoblasts, Osteocytes, and Osteoclasts | the three types of bone cells |
| mineralization | the process by which osteoblasts secrete collage to form a surrounding matrix which then becomes calcified |
| osteocytes | name for osteoblasts when they are surrounded by calcified matrix |
| Osteoclasts | large multinucleate cells that break down previously formed bone by secreting hydrogen ions which dissolve crystals and hydrolytic enzymes |
| Parathyroid Hormone (PTH) | a hormone that controls directly or indirectly the bone, kidney, and GI tract |
| parathyroid gland | the endocrine gland that produces parathyroid hormone |
| 1,25-dihydroxyvitamin D (1,25-(OH)2D) | the active form of vitamin D that stimulates the intestinal absorption of Ca2+ |
| Calcitonin | a peptide hormone secreted by cells called parrafollicular cells. It decreases plasma concentration of Ca2+ mainly by inhibiting osteoclasts thereby reducing bone resorption. It is stimulated by the increase in plasma Ca2+ concentration |
| Rickets | a condition in children in which mineralization of bone matrix is deficient causing bones to be soft and easily fractured |
| Osteomalacin | a condition in adults in which mineralization of bone matrix is deficient causing bones to be soft and easily fractured |
| Osteoporosis | a disease in which both matrix and minerals are lost as a result of an imbalance between bone resorption and bone formation |
| Bisphosphonates | a group of drugs that interfere with the resorption of bone by osteoclasts |
| Hypercalcemia | a dramatic increase in Ca2+ levels due to an excess amount of PTH |
| Primary Hyperparathyroidism | a disease that causes hypercalcimia due to excessive secretion of PTH most likely cause by an adenoma on the parathyroid gland |
| Humoral hypercalcemia of malignancy | a type of cancer that causes hypercalcimia by secreting a PTH-related peptide |
| Hypocalcemia | a dramatic decrease in plasma levels of Ca2+ |
| primary hypoparathyroidism | a disease that causes hypocalcemia because of a malfunction of the parathyroid glad |
| pseudohypoparathyroidism | A disease that leads to the symptoms of hypocalcemia due to resistance of effects of PTH on target tissue evn though PTH levels seem to be in excess |
| secondary hyperparathyroidism | a disease that causes a hypocalcemic state due to failure to absorb vitamin D from the GI tract or decreased kidney 1,25-(OH)2 production |
| hypocalcemic tetany | a symptom of hypocalcemia that appears in the form of muscle spasms |
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