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Chapter 6 Notes

Chapter 6 Notes. Osseous Tissue and Bone Structure. 6.1. Intro to the skeletal system A. includes the bones, cartilages, ligaments B. Functions: five primary 1. support- provide framework for muscle attachment 2. Stores minerals & lipids

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Chapter 6 Notes

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  1. Chapter 6 Notes Osseous Tissue and Bone Structure

  2. 6.1 • Intro to the skeletal system A. includes the bones, cartilages, ligaments B. Functions: five primary 1. support- provide framework for muscle attachment 2. Stores minerals & lipids -bones store calcium and phosphate ions -store lipids in yellow marrow

  3. 3. produce blood cells- red marrow produces red and white blood cells 4. protection -protect soft tissues and organs - ribs protect heart and lungs 5. leverage -can change direction and amount of force produced by muscles - allow for precise motion

  4. 6.2 II. Bone classifications A. Shapes -typical adult skeleton has 206 bones - divided into 6 shape based categories 1. long bones- long and slender - found in arm, forearm, thigh, leg, fingers & toes -femur is the largest &heaviest bone in the body 2. flat bones- thin parallel surfaces - form the roof of the skull, sternum, ribs -protect underlying soft tissues - attachment site for muscles

  5. 3. sutural bones- (Wormian bones) - small, flat, irregular shaped - in skull - jigsaw borders 4. irregular bones -complex shapes -short, flat, ridged surfaces - spinal vertebrae, some skull bones 5. short bones -small & boxy -wrist & ankle bones 6. sesamoid bones (shaped like sesame seed) - generally small, flat -develop inside tendons -located near joints -kneecap

  6. B. Bone markings PAGE 187 -surface features -grouped as projections, depressions, openings - can provide info like age, sex, size 1. elevations/projections -form where tendons and ligaments attach -where bones join (joints) 2. depressions/grooves -form sites where blood vessels or nerves lie along surface or go through bone

  7. C. Bone structure 1. parts of long bone a. diaphysis- shaft, made of compact bone b. metaphyses- area between shaft and end (epiphyses) c. epiphyses- expanded area at end of shaft d. medullary cavity- space in shaft for red or yellow bone marrow 2. bone tissue a. compact tissue -relatively solid, dense -forms protective layer around medullary cavity b. spongy bone (cancellous) -open network, porous -covered by thin covering of compact bone (cortex)

  8. 6.3 III. Bone Matrix and Cell types Osseus tissue is a supporting connective tissue Why? –specialized cells -matrix of extracellular protein fibers & ground substance A. bone matrix 1. bone weight 2/3 from calcium phosphate 1/3 from collagen fibers 2% of mass contributed by cells

  9. 2. Calcium phosphate interacts w/ calcium hydroxide -forms hydroxyapatite crystals 3. Calcium crystals are hard but brittle -can tolerate compression -can’t tolerate twisting or sudden impact 4. Collagen fibers are very strong -provide framework for crystals to form on -are flexible, can bend -don’t resist compression 5. fibers &crystal combination allows bone to be strong, somewhat flexible, resistant to shattering

  10. B. Cells in bone 1. osteocytes-mature bone cells - make up most of cell population -each occupies a lacuna, a pocket in layers of matrix(lamellae) - can’t divide - rely on canaliculi (passageways through lamellae) to connect lacunae w/ one another & nutrient source - Functions: *create chemicals that dissolve matrix & rebuild the matrix, stimulating deposition of crystals *can convert to other cell types in case of bone injury (released from lacunae)

  11. 2. osteoblasts- produce new bone (process of osteogenesis) - make & release proteins for matrix - organic component of matrix is called osteoid - elevate calcium phosphate levels to trigger the deposit of salts - turn into osteocytes once surrounded by matrix 3. osteoprogenitor cells- stem cells -divide to produce cells that become osteoblasts - maintain osteoblast populations - important in repairing fractures - located on outer surface of bone (periosteum) & inner layer lining medullary cavity (endosteum)

  12. 4. osteoclasts- remove recycle bone matrix - giant cells - 50+ nuclei -not related to other bone cells, but come from stem cells that produce macrophages -secrete enzymes that dissolve matrix and release stored minerals (osteolysis) -helps to regulate calcium & phosphate concentrations in body fluids 5. balance bwtn osteoblasts & osteoclasts is important in maintaining bone health---too much osteoclast activity will weaken bones

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