Physiology 4530A/B Final: Final Exam Notes
13 Apr 2017
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Endochondral ossification: most bones (axial and appendicular) (through cartilage intermediate) Periosteum: layer of fibroblastic tissue surrounding bone for cycling and regulating growth. Osteoblasts (become osteocytes when embedded in bone) Chondrodysplasia: mutations in fgfr3, sox9, col ii. Achondroplasia: gof constitutive fgfr, so chondrocytes go straight to hypertrophy and haven"t proliferated enough. Can"t do in vitro so need animal models like mouse: economic because of size, lifespan is short, easily genetically manipulated (combined with surgery, diet, drugs, exercise, easily) They differentiate into chondrocytes (via chondrogenesis with sox9) This is when they are terminally differentiated. Cartilage is vascularized, then breaks down, then bone is formed: limiting factor is nutrient and o2 can run out, so hypoxia occurs, which activates. Hif1alpha, which activates vegf angiogenesis, creating blood vessels and osteoblast/clast precursors calcification of matrix (osteoclasts resorb cartilage, osteoblasts lay down bone) Primary ossification: 1st time vascularization happens (in centre of bone; at ends, they are still proliferating.
