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2010-09-08 17:52:15
connective tissue

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  1. stroma
    connective and non-functional supportive framework of a cell or tissue or organ
  2. parenchyma
    the functional part of a cell or tissue or organ (as compared to the stroma)
  3. extracellular matrix
    made up of protein fibers and ground substance
  4. ground substance
    a hydrophilic complex of anionic macromolecules and multiadhesive glycoproteins that stabilizes the extracellular matrix
  5. protein fibers
  6. structure of loose/areolar connective tissue
    few cells; disorganized fibers; abundant ground substance; little tensile strength
  7. structure of dense regular connective tissue
    abundant collagen fibers arranged in the same direction
  8. structure of dense irregular connective tissue
    predominant collagen fibers loosely arranged in bundles w/o specific orientation
  9. function of loose/areolar connective tissue
    holds blood; supports epithelium; arena for immune function and nutrient exchange
  10. function of dense regular connective tissue
    mechanical coordination and support; withstand stress from one particular direction
  11. function of dense irregular connective tissue
    mechanical support and integrity; withstand stress from many directions
  12. epidermis
    outer layer of skin; consists of epithelium plus loose connective tissue
  13. dermis
    layer of dense irregular connective tissue underlying the epidermis
  14. ligament
    connects bone to bone; made up of dense regular connective tissue
  15. tendon
    connects bone to muscle; made up of dense regular connective tissue
  16. cornea structure
    composed of alternating lamellae of collagen I fibers arranged perpendicularly for mechanical strength and transparency
  17. migratory CT cells
    derived from hemtopoeitic stem cells; include immune cells and osteoclasts
  18. resident CT cells
    derived from undifferentiated mesenchymal cells; include stationary connective tissue cells
  19. fibroblasts
    most abundant connective tissue cell type; secrete collagen & elastin & proteoglycans & associative proteins & growth factors; produce fibers; repair injured connective tissue
  20. reticular cells
    specialized fibroblasts; produce reticular fibers made of type III collagen; produce supporting network for organs that change size/shape
  21. unilocular adipose tissue
    "common ""yellow fat;"" color from dissolved carotenoids; main fat type in adults; one large lipid molecule in center"
  22. multilocular adipose tissue
    """brown fat;"" color from mitochondrial carotenoids and capillaries; common in newborns and hibernating animals; important in non-shivering thermogenesis; lipids organized into droplets"
  23. proteoglycan structure
    brush-shaped structure with rod-shaped protein core and negatively charged GAG extensions; retain water
  24. glycoprotein structure
    globular proteins with branched monosaccharides
  25. aggrecan
    largest proteoglycan; involved in hydration of collagen extracellular matrix; abundant in loose connective tissue
  26. decorin
    a type of proteoglycan; involved in collagen fibrillogenesis and cell signaling
  27. versican
    a type of proteoglycan; binds to fibulin; involved in cell-cell and cell-matrix interactions
  28. syndecan
    a type of proteoglycan; binds extracellular matrix and intracellular actin
  29. secondary structure of collagen
    alpha helical organization
  30. tertiary structure of collagen
    triple helical organization; coiled-coil; glycines to the inside
  31. quarternary structure of collagen
    microfibrils and fibrils aligned rod-like oligomers
  32. aminoacid composition of collagen
    33% glycine; 10% proline; 10% hydroxyproline
  33. procollagen
    precursor to tropocollagen; terminal propeptides have not yet been cleaved; synthesized collagen fibers have been assembled and hydroxylated; ready for export out of cell
  34. tropocollagen
    product once terminal propeptides have been cleaved from procollagen; occurs extracellularly
  35. lacunar region of collagen fibril
    light-colored striated area between collagen fibers; makes up about 90% of collagen length
  36. overlapping region of collagen fibril
    dark-colored striated area in which collagen fibers overlap; makes up about 10% of collagen length
  37. lysyl oxidase
    an extracellular enzyme that is involved in the cross-linking of collagen fibers
  38. Ehlers-Danlos Type IV deficiency
    results from haploinsufficiency; faulty transcription of collagen type III; results in aortic and/or intestinal rupture
  39. Ehlers-Danlos Type VI deficiency
    results from enzymatic insufficiency; faulty lysine hydroxylation; results in augmented skin elasticity and rupture of eyeball
  40. Ehlers-Danlos Type VII deficiency
    results from enzymatic insufficiency; decrease in procollagen peptidase activity; results in increased articular motion and joint dislocation
  41. scurvy
    results from enzymatic insufficiency; lack of vitamin c - cofactor for proline hydroxilase; results in hemorrhages and ulceration of gums
  42. osteogenesis imperfecta
    dominant negative mechanism of transmission; change in one nucleotide for the collagen I gene causes misfolding of proteins; results in spontaneous fractures and cardiac insufficiency
  43. haploinsufficiency
    occurs when a diploid organism has only one functional copy of a gene
  44. dominant negative mutations
    a mutation that reduces the functioning or stability of other related proteins
  45. lysine hydroxylase deficiency
    disrupts fross-linking of collagen fibers; results in hypermotility of joints and easy bruising and poor wound healing and scarring
  46. reticular fibers
    composed of collagen type III; thin and branching
  47. elastic fibers
    thin fibers made up of the glycoprotein fibrillin; form sparse networks interspersed with collagen; confer elasticity and resilience to many tissues; found in large arteries and lungs and skin and ligaments and tendons
  48. Marfan syndrome
    autosomal dominant disorder; caused by mutations in the fibrillin gene; can lead to death by aortic rupture
  49. cutis laxa
    caused by mutations in the elastin gene; causes loose skin and can cause emphysema and heart problems
  50. associative elements
    glycoproteins that link fibers in ECM with cellular receptors; include fibronectin and laminin and tenascin and entactin
  51. integrins
    receptors that mediate attachment between a cell and its environment; anchor cells to the ECM
  52. cartilage
    semi-rigid form of avascular connective tissue; characterized by predominant ground substance/ECM
  53. chondrocytes
    connective tissue cells found in cartilage; synthesize and produce extracellular matrix
  54. hyaline cartilage
    the most common form of cartilage; transparent and smooth; smooth texture ideal for articulations; primarily composed of type II collagen
  55. fibrocartilage
    combination of dense connective tissue and cartilage; has cells in individual lacunae arranged in rows; found where resistance to shearing and compressing forces are required; high combination of collagen I fibers
  56. elastic cartilage
    a flexible and elastic cartilage; many elastic fibers; cells closely packed and disorganized; found in ear and nose and epiglottis
  57. osteoclasts
    multi-nucleated giant cells involved in the resporption and remodeling of bone; derived from monocytes
  58. osteocytes
    mature bone cells; develop from osteoblasts that have secreted matrix; sit in lacunae of bone
  59. osteoblasts
    bone cells found at the surface of bone; synthesize organic components of matrix
  60. osteoid
    "unmineralized matrix; ""pre-bone"""
  61. lacunae of bone
    cavities in the lamellae of bone in which osteocytes reside
  62. canaliculi
    thin cylindrical spaces that perforate bone matrix; allow for exchanges between osteocytes and blood capillaries
  63. cell processes
    allow for biochemical coupling of osteocytes; rely upon gap junctions
  64. Howship lacunae
    enzymatically etched depressions in which osteoclasts lie; formed during the process of resorption
  65. bone resorption process
    osteoclasts attach to bone surface via integrins and seal area to be degraded; osteoclasts release HCl to degrade minerals; osteoclasts release protesases to degrade collagen
  66. ruffled border
    irregular projections formed by the border of active osteoclasts against bone matrix
  67. osteopetrosis
    a condition mediated by defective osteoclast activity; leads to excessively hard and brittle bones and increased propensity for bone fractures
  68. Paget's disease
    a condition initially marked by excessive large osteoclast activity
  69. matrix vesicles
    foci for deposition of hydroxyapatite; site of mineralization; contain alkaline phosphatase
  70. osteomalacia
    deficient bone mineralization in adults
  71. rickets
    deficient bone mineralization in children
  72. cancellous bone
    porous bone; has large surface area for mineral exchange; adds support without weight; also called trabecular or spongy bone
  73. trabecular bone
    porous bone; has large surface area for mineral exchange; adds support without weight; also called cancellous or spongy bone
  74. spongy bone
    porous bone; has large surface area for mineral exchange; adds support without weight; also called cancellous or trabecular bone
  75. compact bone
    "dense areas of bone without cavities
  76. cortical bone
    "dense areas of bone without cavities
  77. medullary cavity
    central marrow-containing cavity of the bone; confers resistance without weight
  78. osteon
    the structural unit of bone; also called the Haversian system
  79. Haversian system
    the structural unit of bone; also called the osteon
  80. cement line
    a collagen-rich layer defining the outer boundary of an osteon
  81. Volksmann's canal
    tubes that run perpendicular to Haversian canals; connect Haversian canals
  82. collagen
    the most abundant protein in the human body; makes up 30% of dry weight; has a mainly structural function
  83. types of collagens
    fibril-forming collagens; network-forming collagens; fibril-associated collagens; transmembrane collagens; anchoring fibril-forming collagens
  84. fenestrated layers
    layers of elastin produced by smooth muscles; found in arteries
  85. elastin production
    secreted by fibroblasts in connective tissue and smooth muscle cells in blood vessels
  86. basement membrane
    structural attachment site for overlaying epithelia and underlying connective tissue; synthesized by epithelial cells
  87. functions of connective tissue
    support and packing; transport; storage; defense; repair
  88. perichondrium
    a layer of dense connective tissue that surrounds cartilage in most places; forms an interface between cartilage and tissue; harbors vascular supply; not present in fibrocartilage
  89. interstitial growth
    a type of chondrogenesis in which preexisting chondrocytes divide mitotically
  90. appositional growth
    a type of chondrogenesis in which perichondrial cells differentiate into chondrocytes
  91. intramembranous ossification
    a method of bone formation in which osteoblasts differentiate directly from mesenchyme and begin secreting osteoid; occurs in bones of the face and skull
  92. endochondral ossification
    a method of bone formation in which the matrix of preexisting hyaline cartilage is eroded and replaced by osteoblasts producing osteoid
  93. Haversian canal
    a series of concentric circular tubes in an osteon; contain blood vessels and nerves