Compact BoneSpongy BoneRelatively dense, solidOpen networkForms the wallsInternal layer surrounding the medullary (marrow)Huge blood supplyNot as much blood supplyWeight barringNot weight barringBlood vessels trapped within matrixNo blood vesselsKIN 3304 1nd Edition Lecture 3 Outline of Last Lecture I. Membranous Organelles cont.II. LysosomesIII. PeroxisomesIV. PlasmalemmaOutline of Current Lecture I. Composition of BonesII. Periosteum and Lacunae and OsteoIII. Compact Bone vs. Spongy BoneIV. Anatomy of BoneV. PeriosteumVI. Bone Development and GrowthVII. OssificationCurrent LectureI. Composition of Bonesa. ~1/3 of matrix consists of collage fibersb. Also Ca2+ saltsi. Calcium Phosphate Ca3(PO4)21. ~2/3 of bone weightii. Calcium Carbonatec. Ca2+ strong but brittled. Collagen by itself weak but flexiblee. Combination of both = strong and flexibleII. Periosteum and Lacunae and Osteoa. Periosteumi. Covers most bone surfacesii. Fibrous outer layer, cellular inner layeriii. Aids in attaching bone to tissue, tendons, ligamentsb. Lacunaei. Space occupied by bone cells1. Within matrix contain osteocytes (bone cells)These 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.ii. Organized around blood vesselsiii. Canaliculi (“little canals” from network (blood and nutrient supply)c. Osteoblasts = buildi. Found on iner/outer surfaces of boneii. Secrete osteoid1. Organic component of bone matrixiii. Responsible for osteogenesis (making the bone)d. Osteoprogenitor Cellsi. Produce daughter cells that differentiate into osteoblastsii. Significant during healing (fractures)iii. Similar to satellite cells in repairing, etc.e. Osteoclasts = clashi. Secrete acids that dissolve bone1. Osteolysisii. Increases Ca2+ and phosphate concentrationiii. Always removing matrix and releasing mineralsIII. Compact Bone vs. Spongy BoneCompact Bone Spongy BoneRelatively dense, solid Open networkForms the walls Internal layer surrounding the medullary (marrow)Huge blood supply Not as much blood supplyWeight barring Not weight barringBlood vessels trapped within matrix No blood vesselsa. Compact Bone a. Osteon is the functional unit of compact boneb. Osteocytes arranged around central canalb. Lamellae a. Calcified matrix (matrices)b. Concentric lamellae align parallel to the long axis of bonei. Concentric lamellaeii. Strengthen the osteonc. Spongy Bonea. Have trabecular branches or spiculesb. Forms an open frameworki. Lighter than compact bone (still strong)ii. Found where bones aren’t heavily stressedIV. Anatomy of Bonea. Cortexi. Surrounds marrowb. Epiphysesi. End of bonec. Diaphysisi. Shafd. Metaphysisi. Connects diaphysis to epiphysisV. Periosteum a. Outer surface of bonei. Isolates/protects bone from surrounding tissueii. Attachment for circulatory, nervous supplyiii. Participates in growth and repairiv. Attaches bone to CT network of deep fasciab. Not present where tendons, ligaments, joint capsules attachc. Becomes interwoven with tendon fibersi. Collagen fibers, called perforating fibersii. “cement” tendon to the bone1. Bond can break bone before tendon snapsiii. At fluid-filled (synovial joint), Periosteum is continued within joint capsuleiv. Near joint, become continuous with CT—1. Helps stabilize jointVI. Bone Development and Growtha. Skeletal growth determines size/proportionb. Begins forming ~6 weeks in embryonic stage, grows until ~25c. Calcification – deposition of Ca2+ salts within tissued. Ossification – during embryonic development, tissues replaced boneVII. Ossificationa. Any tissue can be calcifiedi. Only ossification results in bone formationb. Intramembranous Ossificationi. Bone development from mesenchyme or fibrous CTii. Clavicle, jaw, facec. Endochondral Ossificationi. Bone replaces existing cartilageii. Weight bearing bones formed this wayVIII. Intramembranous Ossificationa. Mesenchymal cells differentiate into osteoblastsi. Begins during 8th week of developmentii. 3 Steps1. Mesenchymal cells differentiate, ossification begins2. Blood vessels trapped in bone3. Becomes spongy boneiii. Step 11. Mesenchymal tissue becomes highly vascularizeda. Cells enlarge, become osteoblastsb. Osteoblasts cluster,i. Secrete component of matrixc. Ca2+ salt, crystalizei. Ossification of boneiv. Step 21. Developing bone grows outwarda. Forms spicules2. Bone growth is activea. Blood vessels grow between spiculesb. Supply nutrients, O2c. More blood flow, more growthv. Step 31. Multiple ossification centers form2. Becomes spongy bone3. Continued deposition of bone results in compact