KIN 3304 1nd Edition Lecture 3 Outline of Last Lecture I Membranous Organelles cont II Lysosomes III Peroxisomes IV Plasmalemma Outline of Current Lecture I Composition of Bones II Periosteum and Lacunae and Osteo III Compact Bone vs Spongy Bone IV Anatomy of Bone V Periosteum VI Bone Development and Growth VII Ossification Current Lecture I Composition of Bones a 1 3 of matrix consists of collage fibers b Also Ca2 salts i Calcium Phosphate Ca3 PO4 2 1 2 3 of bone weight ii Calcium Carbonate c Ca2 strong but brittle d Collagen by itself weak but flexible e Combination of both strong and flexible II Periosteum and Lacunae and Osteo a Periosteum i Covers most bone surfaces ii Fibrous outer layer cellular inner layer iii Aids in attaching bone to tissue tendons ligaments b Lacunae i Space occupied by bone cells 1 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 vessels iii Canaliculi little canals from network blood and nutrient supply c Osteoblasts build i Found on iner outer surfaces of bone ii Secrete osteoid 1 Organic component of bone matrix iii Responsible for osteogenesis making the bone d Osteoprogenitor Cells i Produce daughter cells that differentiate into osteoblasts ii Significant during healing fractures iii Similar to satellite cells in repairing etc e Osteoclasts clash i Secrete acids that dissolve bone 1 Osteolysis ii Increases Ca2 and phosphate concentration iii Always removing matrix and releasing minerals III Compact Bone vs Spongy Bone Compact Bone Relatively dense solid Forms the walls Huge blood supply Weight barring Blood vessels trapped within matrix Spongy Bone Open network Internal layer surrounding the medullary marrow Not as much blood supply Not weight barring No blood vessels a Compact Bone a Osteon is the functional unit of compact bone b Osteocytes arranged around central canal b Lamellae a Calcified matrix matrices b Concentric lamellae align parallel to the long axis of bone i Concentric lamellae ii Strengthen the osteon c Spongy Bone a Have trabecular branches or spicules b Forms an open framework i Lighter than compact bone still strong ii Found where bones aren t heavily stressed IV Anatomy of Bone a Cortex i Surrounds marrow b Epiphyses i End of bone c Diaphysis i Shaf d Metaphysis i Connects diaphysis to epiphysis V Periosteum a Outer surface of bone i Isolates protects bone from surrounding tissue ii Attachment for circulatory nervous supply iii Participates in growth and repair iv Attaches bone to CT network of deep fascia b Not present where tendons ligaments joint capsules attach c Becomes interwoven with tendon fibers i Collagen fibers called perforating fibers ii cement tendon to the bone 1 Bond can break bone before tendon snaps iii At fluid filled synovial joint Periosteum is continued within joint capsule iv Near joint become continuous with CT 1 Helps stabilize joint VI Bone Development and Growth a Skeletal growth determines size proportion b Begins forming 6 weeks in embryonic stage grows until 25 c Calcification deposition of Ca2 salts within tissue d Ossification during embryonic development tissues replaced bone VII Ossification a Any tissue can be calcified i Only ossification results in bone formation b Intramembranous Ossification i Bone development from mesenchyme or fibrous CT ii Clavicle jaw face c Endochondral Ossification i Bone replaces existing cartilage ii Weight bearing bones formed this way VIII Intramembranous Ossification a Mesenchymal cells differentiate into osteoblasts i Begins during 8th week of development ii 3 Steps 1 Mesenchymal cells differentiate ossification begins 2 Blood vessels trapped in bone 3 Becomes spongy bone iii Step 1 1 Mesenchymal tissue becomes highly vascularized a Cells enlarge become osteoblasts b Osteoblasts cluster i Secrete component of matrix c Ca2 salt crystalize i Ossification of bone iv Step 2 1 Developing bone grows outward a Forms spicules 2 Bone growth is active a Blood vessels grow between spicules b Supply nutrients O2 c More blood flow more growth v Step 3 1 Multiple ossification centers form 2 Becomes spongy bone 3 Continued deposition of bone results in compact bone
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