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Skeletal System Overview

Skeletal System Overview. Chapter 7 p. 192 – p. 204. What makes up bone?. Osteocytes (bone forming cells) and extracellular matrix Osteocytes are found in lacunae (holes in the bony matrix) Extracellular matrix is made up of collagen and inorganic salts. Types of Bones. Long bones

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Skeletal System Overview

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  1. Skeletal System Overview Chapter 7 p. 192 – p. 204

  2. What makes up bone? • Osteocytes (bone forming cells) and extracellular matrix • Osteocytes are found in lacunae (holes in the bony matrix) • Extracellular matrix is made up of collagen and inorganic salts

  3. Types of Bones • Long bones • Short bones • Flat bones • Irregular bones • Sesamoid bones

  4. Long Bones • Epiphysis • Articular Cartilage • Diaphysis • Spongy bone • Compact bone

  5. Parts of the Long Bone • Periosteum • Vascular, fibrous outer covering of bone • Endosteum • Lines medullary cavity • Contains bone forming cells • Medullary Cavity • Hollow region of bone • Continuous with the spongy bone • Marrow, blood vessels found here

  6. Spongy Bone • Trabeculae: branching bony plates • Space between the bony plates allows for cushion

  7. Compact Bone • Made up of osteons • Circular units with central blood vessels and nerves • Also called Haversian systems • Resists compression • Volkmann’s canals • Also known as perforating canals • Contain larger blood vessels and nerves • Communicate with surface of the bone

  8. Osteon

  9. Volkmann’s Canals

  10. Short Bones • Make up hands and feet

  11. Flat Bones • Scapula (shoulder blade) • Skull • Ribs

  12. Irregular Bones • Vertebrae • Facial bones

  13. Sesamoid Bones • Not always a separate category • Round bones • Patella

  14. Bone Marrow

  15. Bones under the microscope

  16. Osteoporosis

  17. Bone Development • Osteogenesis: development of bone • Intramembranous Bone (flat bones) • Unspecialized cells appear at site of new bone formation • Blood vessels move into these cells and allow cells to differentiate into osteoblasts • Deposit bony matrix to form spongy bone • Spongy bone would fill in with higher amounts of bony matrix to form compact bone

  18. Bone Development • Endochondral Bones • Develop from masses of hyaline cartilage • Hyaline cartilage lays down basic bone layout • Over time, bone forms over the cartilage template • Osteoblasts form and secrete bony matrix • Once bony matrix surrounds the osteoblasts, they are called osteocytes • Endochondral ossification

  19. Bone Development • Primary ossification center • Bone begins to replace hyaline cartilage in the diaphysis • Osteoblasts in periosteum deposit compact bone • Secondary ossification centers • Epiphyses • Spongy bone • Epiphyseal plate – zone of cartilage between diaphysis and epiphysis

  20. Bone Development

  21. Growth at the Epiphyseal Plate • 4 layers • Resting cartilage • No growth • Closest to the epiphysis • Proliferating cartilage • Young cells, mitosis • Zone of hypertrophic cartilage • Older cells • Zone of calcified cartilage • Dead cells and extracellular matrix

  22. Growth at the Epiphyseal Plate • http://www.gla.ac.uk/ibls/US/fab/tutorial/generic/bone5.html

  23. Osteoclasts • Invade areas of calcified cartilage • Break down extracellular matrix • Osteoblasts then move in • Deposit bony matrix in place of calcified cartilage

  24. Ossification Timetable (p. 200)

  25. Factors Effecting Bone Growth and Repair • Nutrition • Exposure to sunlight • Hormones • Physical exercise • Work with a partner to research a factor effecting bone growth and it’s effect on development • Look up a bone growth disorder, too. (Brief!)

  26. Fractures • Greenstick – incomplete, across bone (usually in developing bone) • Fissured – incomplete, longitudinal • Comminuted – complete, shatters the bone • Transverse – complete, right angle to bone axis • Oblique – at an angle other than a right angle • Spiral – caused by excessive twisting of the bone • Compound – bone breaks the skin

  27. Fractures

  28. Bone Repair • Hematoma forms (blood released from vessels within the bone) • Formation of spongy bone and fibrocartilage • Bony callus • Osteocytes, osteoblasts and osteoclasts

  29. Functions of the Skeletal System • Support and Protection • Movement • Origin and insertion of muscle • Origin: immovable end of the muscle • Insertion: movable end – during contraction, insertion will move toward the origin

  30. Functions of the Skeletal System • Blood production • Hematopoiesis • Bone marrow – long bones, spongy bone, larger canals of compact bone • Red marrow: produces red blood cells, white blood cells and platelets • White marrow: fatty tissue

  31. Functions of the Skeletal System • Inorganic salt storage • Salts account for approximately 70% of extracellular matrix of bone • Mostly calcium phosphate – hydroxyapatite • Also: magnesium, sodium, potassium, carbonate ions • Will also absorb small amounts of harmful metallic elements (lead, strontium)

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