PSIO 201 5th Edition Lecture 11Outline of Last Lecture Bone OrganizationOutline of Current Lecture I. Bone GrowthII. Interstitial Growth III. Growth at epiphyseal plate IV. Appositional GrowthCurrent LectureBone Growth: - Bones in children are not fully developed so they will have more bones then adults; more spaces- Epiphyseal plate located in children but stops function as adut-A) Interstitial Growth- growth from within cartilage; growth in length at epiphyseal plate1. Chondroblasts build matric and differentiate into chondrocytes in ECM2. Chondrocytes divide into isogenic groups3. Chondrocytes build matric and spread apart4. Cartilage tissue grows from withinGrowth at Epiphyseal Plate:1. Interstitial growth of cartilage 2. Endochondral OssificationLayers include:- resting cartilage- proliferating cartilage ( interstitial growth)- hypertonic cartilage- calcified cartilage (will be replaced with bone)- diaphysis bone- Diaphyseal osteoclast will break down calcified cartilage. - Osteoblasts lay down spongy bone- Chondrocytes continue to form cartilage matric at proliferating cartilage region- Growth in length stops when chondroblasts and chondroclasts work faster that chondrocytes at proliferating zone and then epiphyseal plate closed and becomesepiphyseal line.B) Appositional Growth- growth in width1. Periosteal osteogenic cells differentiate into osteoblasts2. Osteoblasts build bone in outer surface and Endosteum 3. Osteoclasts increase the diameter of marrows cavity4. Bone diameter and cortical width increase. 5. Osteons are added to periosteal side of bone by:a) ridges in perosteum create grooves for peristeal blood vesselsb) osteoblasts build now concentric lamellae inward toward center making new
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