100%(1)1 out of 1 people found this document helpful
This preview shows page 5 - 7 out of 13 pages.
-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.
-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 chronicanemia.