PSIO 121 5th Edition Lecture 10Outline of Last Lecture Organization of BoneOutline of Current Lecture I. Spongy Bone and FunctionII. Compact Bone and FunctionIII. Bone Formation and GrowthIV. Intramembranous OssificationV. Endochondral OssificationCurrent Lecture- Rickets Disease – Calcium deficient (inorganic)- Scurvy Disease- Collagen deficient (organic)Spongy Bone: - irregular lattice of thing plats called trabecullae- osteocytes housed in lacunae - Located in epiphysis of long bone surrounding marrow cavities, flat, short, and irregular- Contains ; osteocytes, trabecullae, osteoclasts, lacuna, osteoblasts, concentric lamellae rings, and caniculli. - Lamellae is made out of collagen fibers- Function; withstand forces from many directions- trabecullae are aligned along lines of stress- Lightens the skeleton - Contains red marrow for hemopoiesis Compact Bone:- solid network of bone organized in concentric ring structure called osteonsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Location ; external layer of all bones and diaphysis of long bones- Function; give long bones ability to withstand forces along longitudinal axis.- Osteon’s are the functional unit of compact bone to carry nutrients and remove waste. - Compact bone contains; osteocytes, osteoclasts, osteoblasts, trabecullae, lacuna, lamellae, concentric rings and caniculi. - ONLY FOUND IN Compact Bone: osteons, central canal, perpherating canals, interential lamellae, circumferential lamellae. Bone Formation and Growth:- Fontanel “soft spot” of infants where bone has not yet formed. - Epyphasis of large bone in infants is only made of cartilage.- Bones of the fetus are composed of 1. Loose connective tissue (mesenchyme) 2. Hyline cartilage Ossification – development of bone by replacing Connective TissueA) Intramembraneous Ossification – “within membrane” from mesenchyme to bone- found in cranial bone, mandible, sternum, clavicle- Heterotropic bone formation- Sesamoid bones- Abnormal stress stimulate bone formationSteps:1. development of ossification center2. Calcification 3. Formation of trabecullae4. Development of Periosteum B) Endochondral Ossification- “inside cartilage” mesenchyme to cartilage to bone- growth in length at epiphyseal plate 1. development of cartilage model2. growth cartilage model3. development of primary ossification center4. development medullary cavity5. development 2nd ossification center 6. formation of articular cartilage and epiphysis plate*Primary vs. Secondary
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