Osteogenic cells stem cells found in endosteum and inner layer of periosteum

Osteogenic cells stem cells found in endosteum and

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- Osteogenic cells : stem cells found in endosteum and inner layer of periosteum. + arise from embryonic mesenchymal cells. + multiply continuously and five rise to most other bone cell types. - Osteoblasts : bone-forming cells. + form single layer of cells under endosteum and periosteum + Nonmiotic + Synthesize soft organic matter of matrix which then hardens by mineral deposition. + Stress stimulates osteogenic cells to multiply rapidly and increase the number of osteoblasts which reinforce bone. + Secrete hormone osteocalcin (stimulates insulin secretion of pancreas; increases insulin sensitivity in adipocytes which limits the growth of adipose tissue). - Osteocytes : former osteoblasts that have become trapped in the matrix they deposited + Lacunae: tiny cavities where osteocytes reside + Canaliculi: little channels that connect lacunae + Cytoplasmic processes of osteocytes reach into canaliculi and contact processes of neighboring cells (gap junctions allow for passage of nutrients wastes, signals). + Some osteocytes reabsorb bone matrix while others deposit it. + Act as strain sensors- when stressed, produce biochemical signals that regulate bone remodeling (shape and density changes that are adaptive). - Osteoclasts : bone dissolving cells found on bone surface. + osteoclasts develop from same bone marrow stem cells that give rise to blood cells (different origin from other bone cells) + Ruffled border (large surface area) faces bone. + Cells often reside in resorption bays (pits in bone surface). + Dissolving bone is part of bone remodeling. 4.Bone matrix is 2/3 (inorganic/organic) and 1/3 (inorganic/organic)? 5. Differentiate between Rickets and Osteogenesis imperfecta (Brittle Bone Disease). - Rickets is a disease caused by mineral deficiency and resulting in soft, deformed bones. - Osteogenesis imperfecta (brittle bone disease) results from a defect in collagen deposition. 6. Differentiate between interstitial, concentric, and circumferential lamellae.
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- Interstitial lamellae: fill irregular regions between osteons, - Concentric lamellae: surround a central (Haversian) canal running longitudinally. - Circumferential lamellae: fill outer region of dense bone. 7. Differentiate between red and yellow bone marrow function. - Red marrow (myeloid tissue): contains hemopoietin tissue: produces blood cells. + In nearly every bone in a child + In adults, found in skull, vertebrae, ribs, sternum, part of pelvic girdle, and proximal heads of humerus and femur. - Yellow marrow found in adults + Fatty marrow that does not produce blood. + Can transform back to red marrow in the event of chronic anemia.
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  • Fall '15
  • Anatomy, Bone marrow, Bone Disease

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