Bone structure and physiology Practice Questions and Answers 100% Pass

Bone structure and physiology Practice Questions and Answers 100% Pass Bone - Correct Answer ️️ -One of hardest connective tissues when fully developed It's a mineralised tissue 30% organic material 45% inorganic material What's bone composed of - Correct Answer ️️ -Living cells embedded in a mineralised extracellular matrix What does hydroxyapatite do - Correct Answer ️️ -Provide strength What's function of bone - Correct Answer ️️ -Support the body and protect internal organs Allows movement Haematopoiesis Calcium homeostasis Haematopoeis - Correct Answer ️️ -Production of blood cells Different types of bones - Correct Answer ️️ -Cortical/compact/laminar Trabecular/cancellous Woven bone Cortical/compact/laminar - Correct Answer ️️ -Approx 80% of skeleton, dense, very strong forms the outer layer of all bones Trabecular/ cancellous - Correct Answer ️️ -Porous mesh work of bone Make up approx 20% of the skeleton mainly in axial skeleton Bone strength also determined by the trabecular microstructure can change in disease eg osteoporosis Woven bone - Correct Answer ️️ -Forms quickly during periods of repair or rapid growth and is remodelled into lamellar bone Periosteum - Correct Answer ️️ -Lines the outer surface of cortical bone Alveolar process - Correct Answer ️️ -Thickened ridge which contains the tooth sockets- supports th eteeth Where does the alveolar process sit - Correct Answer ️️ -Outer and inner cortical plates Trabecular or cancellous bone filling Where is periodontal ligament attached - Correct Answer ️️ -Periodontal ligament attached to dentin and alveolar bone When periodontal ligament is squashed - Correct Answer ️️ -Fluid pushed out, inner cortical plate got pores, fluid goes into these into alveolar bone Bone matrix - Correct Answer ️️ -Forms scaffold of interwoven collagen fibres Between fibres are small, uniform , plate like crystals of carbonated hydroxyapatite Small amounts of non collagenous proteins some which are unique to calcified tissue (eg osteocalcin) Cell types in bone - Correct Answer ️️ -Osteoclast Osteoblast Osteocyte Bone lining cells Osteoprogenitor(stromatal cells) Osteoclast - Correct Answer ️️ -Large multi uncleared cells which resorb bones Osteoblast - Correct Answer ️️ -Cells which form bone Osteocyte - Correct Answer ️️ -Originate from osteoblasts which have become embedded in the bone matrix Sensing mechanical loads and Ca2+ homeostasis Bone lining cells - Correct Answer ️️ -Originate from osteoblasts Line quiescent periosteal and endosteal surfaces of bone Osteoprogenitor cells(stromatal cells) - Correct Answer ️️ -Precursors of osteoblastic lineage Bone remodelling - Correct Answer ️️ -To carry out its functions bone is constantly being remodelled Remodelling estimated to occur at 1-2 million microscopic sites/skeleton at any one time Phases of bone remodelling - Correct Answer ️️ -Starts with resorption phase Bone ECM destroyed and removed, this phase takes approx 3 weeks/remodelling site A bone formation phase then follows New ECM is formed and mineralised this phase takes 3-4 months/remodelling site Mechanism of bone remodelling - Correct Answer ️️ -1- recruitment of osteoclast precursors to remodelling sites 2- osteoclast precursors mature into osteoclasts 3- bone living cells erode a little ECM and leave the remodelling site 4- osteoclasts bind to the exposed ECM and digest the bone matrix with enzymes to form resorption pits 5-osteoclasts stop digesting matrix and die(apoptosis) 6- osteoblast precursors recruited to the remodelling site 7- osteoblasts precursors develop into mature osteoblasts 8- osteoblasts make new ECM to fill the resorption pit made by the osteoclasts 9- when the synthesis of matrix is complete the new bone surface becomes covered in bone lining cells Why are mechanical forces/stresssed on bone important - Correct Answer ️️ -For its maintenance and formation particularly for alveolar bone Systematic factors which stimulate bone resorption - Correct Answer ️️ -Parathyroid hormone, 1 -25 dihydroxy vitamine D3. Thyroid hormone, vitamin A, cortisol Parathyroid hormone - Correct Answer ️️ -Receptors for PTH act on cells of Ob lineage Stimulate Ob to produce Oc stimulating factors 1 -25 dihydroxy vitamin D3 - Correct Answer ️️ -Promote Oc precursor differentiation Promote stromatal cell/Ob to produce Oc stimulating facotrs Thyroid hormone - Correct Answer ️️ -Directly stimulates Oc Vitamin A - Correct Answer ️️ -Directly stimulates Oc