Histology of Bone

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Histology of Bone
2015-11-24 18:40:24

Histology of Bone Kalliecharan 11/23-24/2015
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  1. What are the primary functions of bone
    • Mechanical Support
    • Locomotion via tendons
    • Protection of vital organs (skull)
    • Metabolic Reservoir of mineral salts
  2. Ezymatic reactions are dependent on what found in bones
  3. What do osteogenesis imperfecta patients lack
    Type I Collagen
  4. What are considered the support cells in the bones
    Osteoblasts and osteocytes
  5. Resorption and remodeling cells in the bone are
  6. The matrix of the bones is made up of what two substances
    • Inorganic mineral salts
    • Organic materials
  7. Non mineralized organic matrix is called an
  8. The inorganic component of the bone matrix is made up of what elements
    Calcium and phosphorus (Mg, K, and HCO3 minor amounts)
  9. The Ca and Phosphorus form what
    Hydroxyapatitie crystals alongside coll. I
  10. What is the function of the surface crystals of hydroxyapatite
    They form a hydration shell with water allowing ion exchange with the extracellular fluid
  11. Amorphous means
    Non- crystaline solid
  12. The organic component of the bone matrix is made up of
    • 90% Coll I and some Coll V
    • Ground substance in the form of GAG's (Chondroitin sulfate, karatan sulfate, and hyaluronic acid)
  13. What causes the organic matrix to stain basophilic
    The abundance of Coll. I
  14. Glycoproteins in bone such as osteocalcin, osteonectin, and osteopontin. As well as sialoproteins are important in the matrix for
    Binding to crystals, fibers, ground substance, and cells
  15. Ground substance and collagen become mineralized to form
  16. What are the four different cell types in bones
    • Osteogenic (Osteoprogenitors)
    • Osteoblasts
    • Osteocytes
    • Osteoclasts
  17. Osteoprogenitor (Osteogenic) cells are derived from
  18. Osteoprogenitor cells can differentiate into what cells
    • Fibroblasts
    • Osteoblasts
    • Chondrogenic cells
  19. Where are the Osteoprogenitor cells found
    • Lining the haversian canals
    • Inner cellular layer of the periosteum
  20. The bone grows only by what means
  21. Osteoblasts form
    • The matrix of the bone
    • - Coll I
    • - GAG's
    • - Glyco proteins
    • - Osteoids
  22. What shape are the osteoblasts
    Cuboidal or columnar
  23. Why do the osteoblasts stain basophilic
    The extensive RER gives them a negative charge
  24. How do the Osteoblasts and Ostecytes communicate
    Gap Junctions
  25. Alk. Phosphatase is used
    As a marker in blood samples for the status of bones
  26. Osteoblasts secrete vesicles into the matrix high in
    • Ca
    • PO4 ions
    • ATPase
    • Alk. Phosphotase
    • Pyrophosphatase
  27. What cleaves PO4 from the extracellular matrix
    • Alk. Phosphatase
    • Pyrophosphatase
  28. What happens when the concentration of Ca and PO4 increase
    They form CaPO4 and growing hydroxyapitite crystals burst the membrane of matrix vesicles
  29. What surrounds osteoblasts and acts as a site of initiation
  30. Rapid growth of hydroxyapatite crystals are deposited where
    Into gap regions of collagen mineralizing the matrix
  31. Osteocytes are, and perform what
    • Mature bone cells
    • Perform maintenance of bone matrix
  32. Osteocytes are dervived from
  33. What surrounds osteocytes
    Lacunar space
  34. What unique feature allows the Osteocytes to communicate outside the lacuna
  35. Through what means do Canaliculi communicate
    Gap Junctions, with other osteocytes and Osteoblasts
  36. What type of things are transported in the canaliculi
    Ions and small molecules
  37. What is found in canaliculi
    • Ions
    • Small molecules
    • Nutrients
    • Matabolites
    • Extracellular Fluid
  38. Osteocytes have what physical features
    • Almond shaped
    • reduced RER and Golgi
  39. What results in the death of osteocytes
    Resorption of the matrix
  40. What are the three functional states of an osteocyte
    • Quiescent
    • Formative
    • Resorptive
  41. In the quiescent stage of an osteocyte
    There is scant RER
  42. In Formative osteocytes
    There is lots of RER, deposition of osteoids in the pericellular space with the lacuna
  43. Resorptive osteocytes have what organelles in abundance and perform what function
    Lots of RER (making lysosomes), Golgi (removing matrix into the blood), and secretory lysosomes.
  44. The pericellular space has no
    Collagen fibrils
  45. Osteocytic osteolysis is
    Resorption stage of osteocytes when Ca is released
  46. Osteoclasts are derived from
    Monocytes fusing, they are large cells with 5-50 nuclei
  47. Osteoclasts have abundant
    • Mitochondria
    • Golgi
    • RER
    • Lysosomes
  48. Osteoclasts have a membrane that
    Is ruffled on the bone side and a clear zone that demarcates the area of bone to be resorbed
  49. The clear zone of an osteoclast has abundant
  50. Osteoclasts have what two phases of resorption
    Initial dissolution of Ca salts by organic acids from PM

    Subsequent enzymatic degredation of collagen by lysosomal enzymes (collagenase, Proteolytic enzymes)
  51. Osteoclasts do not belong to what family
    Osteogenic, made by monocytes
  52. PTH has what effect on osteoblasts
    • It stimulates them to release osteoclast stimulating factor causing the osteoclasts to absorb bone
    • It can also affect osteoclasts directly
  53. What effect does calcitonin have on osteoclasts
    Reduces the bone resorption of osteoclasts
  54. High calcitonin shuts off
    PTH release
  55. Somatotropin can have what effects when not in balance
    Gigantism when high, dwarfism when low
  56. What are the two types of bone on a microsopic level
    • Primary - Immature or woven, first to form, abundant osteocytes, no arrangement, found in fetal and bone development
    • Secondary - mature, found in adults, strong bone, replaces primary, in parallel array
  57. What are the two types of bone marrow, where are they found, and what do they do
    • Red - found in the sternum, ribs, ends of long bones, make blood cells
    • Yellow bone - diaphyseal cavity of long bones, stores fat
  58. Bone grows only by what means
  59. When the matrix is calcified it is considered
    Strong bone
  60. Intramembranous bone is formed in what order
    • Mesenchyme
    • Osteogenic cells
    • Osteoblasts
    • Spongy bone (trabeculae, cancellous)
    • Primary bone
    • Secondary bone (lamellar)
  61. What two phases make up the Endochondral Ossification
    • Hypertrophy and destruction of chondrocytes
    • Osteogenic budding
  62. When a bone is fractured what takes place
    • The periosteum covers the fragments
    • Hyaline cartilage follows
    • Bone is formed around a callus
    • Fracture is healed
  63. What is the role of vitamin D in bone formation
    It is necessary for the absorption of Ca from the intestines
  64. Deficiency in Vitamin C, D, or phosphorus will lead to
    Rickets in children osteomalacia in adults (major problem in pregnancy), child normally has bowed legs
  65. Vitamin C has what function in bone formation
    It is necessary for collagen formation, lack of vitamin C causes Scurvy
  66. What is the role of vitamin A in bone formation
    Lack of it inhibits proper bone formation, excess causes early ossification of epiphyseal plates
  67. Osteopetrosis is when
    There is no ruffled boarder in the osteoclasts and therefore high density of bones
  68. Osteoporosis is when
    There is a low bone density due to increase bone resorption, or decrease bone formation
  69. Acromegaly is
    An excess of GH causing gigantism affects
  70. Papain can have a negative effect because
    It destroys gound substance of cartilage resulting in lose of rigidity