The regulation of bone remodeling is both systemic and local. The major systemic regulators include parathyroid hormone (PTH), calcitriol, and other hormones such as growth hormone, glucocorticoids, thyroid hormones, and sex hormones.
What causes the constant remodeling of bone?
Bone remodeling is thought to be regulated by many factors including nutritional status, humoral factors, and biomechanical stress. However, the involvement of the autonomic nervous system, mainly the sympathetic nervous system (SNS), in the modulation of bone remodeling is beginning to receive more attention.
Is bone remodeling a continuous process?
There are five phases in the bone remodeling process: ACTIVATION, RESORPTION, REVERSAL, FORMATION, and QUIESCENCE. The total process takes about 4 to 8 months, and occurs continually throughout our lives.
What cells are responsible for bone remodeling?
Bone remodelling relies on the correct function of two principal cells of the bone tissue: the osteoclasts, multinucleated cells that destroy the bone matrix, and the osteoblasts, having osteogenic functions.
What are the 2 main hormones in bone remodeling?
PTH and PTHrP. PTH is a hormone synthesized and secreted by the parathyroid glands. The main function of PTH is to maintain blood calcium homeostasis. In addition, PTH regulates bone mass in an endocrine manner (52).
What is the role of calcium in bone remodeling?
Calcium is the major component of the bone, where it is present at more than 99% as calcium-phosphate complexes, and provides the skeleton strength and structure, making the bone a metabolic reservoir to maintain the intra- and extra-cellular calcium pool.
What is the mechanism of bone remodeling?
Bone remodeling involves tight coupling and regulation of osteoclasts and osteoblasts and is modulated by a wide variety of hormones and osteocyte products secreted in response to mechanical stimulation and microdamage.
Which hormone is responsible for bone growth?
Testosterone is important for skeletal growth both because of its direct effects on bone and its ability to stimulate muscle growth, which puts greater stress on the bone and thus increases bone formation. Testosterone is also a source of estrogen in the body; it is converted into estrogen in fat cells.
What is the role of osteoclasts in bone remodeling?
Osteoclasts are the cells that degrade bone to initiate normal bone remodeling and mediate bone loss in pathologic conditions by increasing their resorptive activity. They are derived from precursors in the myeloid/monocyte lineage that circulate in the blood after their formation in the bone marrow.
How is bone remodeling accomplished quizlet?
How is bone remodeling accomplished? Osteoblasts form new bone matrix and Osteocytes remove and replace calcium salts.
Does Calcitonin affect bone remodeling?
Bone is in a constant state of remodeling. Old bone is removed by cells called osteoclasts, and new bone is added by cells called osteoblasts. Calcitonin inhibits bone removal by the osteoclasts and at the same time promotes bone formation by the osteoblasts.
What factors affect bone growth and bone remodeling?
Bone growth factors affect the process of bone remodeling. These factors include insulin-like growth factors I and II, transforming growth factor beta, fibroblast growth factor, platelet-derived growth factor, and bone morphogenetic proteins. Bone volume is determined by the rates of bone formation and bone resorption.
Which of the following hormones maintains bone?
Growth Hormone (GH): This hormone plays key roles in the growth of bones during childhood, but also maintains bone health in adulthood.
What is the bone remodeling cycle?
During the bone remodelling cycle, osteoclastic resorption is tightly coupled to osteoblastic bone formation. The remodelling cycle occurs within the basic multicellular unit and comprises five co-ordinated steps; activation, resorption, reversal, formation and termination.
How are bone cells involved in bone remodeling quizlet?
-Osteoclasts are involved in the remodeling process. -Bone remodeling is a combination of bone deposition and resorption. -Bones are remodeled to accommodate the stresses put on them. Osteoclasts are involved in the remodeling process.
Which cells are involved in bone resorption quizlet?
Osteoclasts are large multinuclear phagocytic cells, located within or adjacent to a depression or pit on bone surface called a resorption lacuna, involved in breaking down in an important process called bone resorption.
What is calcitonin function?
What is calcitonin? Calcitonin is a hormone that your thyroid gland makes and releases to help regulate calcium levels in your blood by decreasing it. Calcitonin opposes the actions of the parathyroid hormone, which is a hormone that increases your blood calcium levels.
What is the function of calcitonin and parathyroid hormone?
Parathyroid hormone (PTH) and calcitonin (CT) are two peptide hormones that play important roles in calcium homeostasis through their actions on osteoblasts (bone forming cells) and osteoclasts (bone resorbing cells), respectively.
How do hormones and physical stress regulate bone remodeling?
Explain how hormones and physical stress regulate bone remodeling. Falling Ca++ levels cause thryoid gland to release PTH, PTH causes osteoclasts to degrade matrix which releases Ca++ into blood. If too much Ca++, calcitonin secreted and stimulates calcium salt deposit into bone.
Which hormone increases osteoclast activity?
PTH receptor signaling in osteoblasts and osteocytes can increase the RANKL/OPG ratio, increasing both osteoclast recruitment and osteoclast activity, and thereby stimulating bone resorption.
What is the relationship between bone remodeling and blood calcium levels?
Parathyroid hormone (PTH) is an important contributor to the bone remodeling process. High levels of PTH can activate osteoclasts and cause excessive bone breakdown. Calcium in your blood triggers the release of PTH. Low calcium levels in the blood, or hypocalcemia, can cause high levels of PTH.
What are 4 factors that stimulate bone growth?
Summary. Bone contains several growth factors, including bone morphogenetic proteins (BMPs), transforming growth factor beta (TGF-β), insulin-like growth factors I and II (IGF-I and IGF-II), platelet derived growth factor (PDGF) and basic and acidic fibroblast growth factor (bFGF and aFGF).
What stimulates osteoblast activity?
Additional components known to enhance osteoblast differentiation are strontium, isoflavones, and whey protein [40–42]. Whether any of these dietary components actually leads to an increase in the anabolic response of bone tissue—as a whole—to mechanical loading remains to be investigated.
What is the role of vitamin D in bone development?
Vitamin D is necessary for strong bones and muscles. Without Vitamin D, our bodies cannot effectively absorb calcium, which is essential to good bone health. Children who lack Vitamin D develop a condition called rickets, which causes bone weakness, bowed legs, and other skeletal deformities, such as stooped posture.
Which of these cells is responsible for bone remodeling quizlet?
 Two main types of cells are responsible for bone metabolism: osteoblasts (which secrete new bone), and osteoclasts (which break bone down).