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WK8 A&P part 2

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winniesmith's version from 2016-12-14 13:49

Section 1

Question Answer
What are the 3 types of bone growth intramembraneous ossification, endochondral ossification, appositional bone growth
What is ossification?conversion of tissues to bone.
How do you form osteoblasts?Mesenchymal (stem cells) differentiate to osteoblasts
Describe the process of intramembranous ossifciationMesenchymal cells aggregate, differentiate into osteoblasts, and begin ossification process.Spicules interconnect, and trap blood vessels within the bone. Spongy bone formed, may be remodeled into compact bone or medullary cavity.
Describe the process of endochondral ossification(Cartilage replaced by bones) Most common. Chondrocytes at the centre of the growing cartilage model enlarge and then die as the matrix calicifies.Newly derived osteoblasts cover the shaft of the cartilage in a thin layer of bone. Blood vessels penetrate the cartilage. New osteoblasts form a primary ossification centre.The bone of the shaft thickens, and the cartilage near each epiphysis is replaced by shafts of bone. Blood vessels invade the epiphyses and osteo-blasts form secondary centres of ossification.
Describe the process of appositional bone growthBone width. Bone deposited by osteoblasts (around outside) and bone reabsorbed by osteoclasts in centre.
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Section 2

Question Answer
what supplies blood to the bone Nutrient Artery and Vein. Metaphyseal Vessels. Periosteal vessels.
Nutrient Artery and Vein Enter the diaphysis through the nutrient foramen.
Metaphyseal Vessels Supply the epiphyseal cartilage
Periosteal Vessels Supply superficial osteons.
Requirements for normal bone growthMinerals (Ca+ and P) Vitamins (D3,C,A) Hormones (growth,sex, thyroid). Loading.
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Section 3

Question Answer
What is remodelling Continuous breakdown and reforming of bone tissue (shape reflect applied load).
What is the role of remodeling To shape/rebuild bone and mineral turnover, important for calcium homeostasis (99% of Ca stored in bone)
How do hormones control storage/release of Ca+PTH releases bone calcium. Calcitonin stores bone calcium.
Remodelling of trabecular boneOsteoclasts- dissolve old bone, Osteoblasts- secrete osteoid(protein)&mature into osteocytes. Osteoid mineralised to form new bone.
Remodelling of cortical boneOsteoclasts form cutting cone in oesteon (bone resorption cavity (tear drop). Osteoblasts form closing cone of osteoid (unmineralised bone)
At what age does your bone mass peak usually 30s
When does bone loss occur?from 40s, most rapid loss in women after menopause.
Where is trabecular bone most affected Epiphyses,Vertebrae, Jaws
how do you assess bones?Dual X-ray absorptiometry (DXA)
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Section 4

Question Answer
What is OsteoporosisOsteoporosis is a systemic skeletal disease. Characterised by low bone mass and microarchitectural deterioration of bone tissue, thus increasing bone fragility and susceptibility to fracture.
Risk of Osteoporosis in UK1 in 2 for women, 1 in 5 for men.
What is a fracture A crack or break in a bone
What are the steps in fracture repairFracture haematoma,mitoses in periosteum,endosteum (internal and external callus). Bone remodeling.
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