connective tissue

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connective tissue
2011-08-23 20:17:06
histology connective tissue

MS1/Mod 1: histology; connective tissue
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  1. collagen type 1
    most common; widespread distribution, "classic collagen"
  2. collagen type 2
    found in hyaline, elastic cartilage and fibrocartilage (intervertebral disks)
  3. collagen type 3
    assoc w/ type 1; "reticular fibers"; structural scaffolding of lymphoid tissues and bone marrow
  4. collage type 4
    basal lamina
  5. What is connective tissue derived from?
    • splanchnic mesoderm (walls of GI tract)
    • somatic mesoderm (body walls)
  6. What is the pathway of collagen formation?
    preprocollagen (rER)--->procollagen (w/in rER)--->tropocollagen/collagen (outside cell via protease)--->collagen fibrils (outside cell)--->collagen fibers (in ECM)
  7. What is CT comprised of?
    collagen and proteoglycans
  8. What are proteoglycans made of?
    glycosaminoglycans (GAGs) and a protein core
  9. What (primarily) makes GAGs and collagen?
  10. How do GAGs make a hydrated gel?
    GAGs have lots of negative charges and attract Na+ which allows water to follow...hydrated gel
  11. What is the function of the hydrated gel of GAGs?
    rapid diffusion of water soluble molecules through ground substance and slowing the passage of lg molecules and bacteria
  12. What can synthesize collagen?
    fibroblasts/fibrocytes, sm muscle cells, chrondroblasts/chondrocytes, osteoblasts/osteocytes
  13. Where else is collagen found besides CT?
    reticular layer of basement membrane
  14. Where are reticular fibers synthesized?
    fibroblasts/cytes in LCT and reticular cells in lymphoid tissues and in bone marrow
  15. What are the functions of reticular fibers?
    supportive lattices in LCT near epithelium and adipose tissue; hematopoietic and lymphoid tissues
  16. What is the composition of elastic fibers?
    elastin protein and fibrillin (glycoprotein)
  17. What makes elastic fibers?
    smooth muscle cells, fibroblasts/cytes, chondroblasts/cytes
  18. What are some physical characteristics of elastic fibers?
    not easily seen w/ reg staining; highly pliable and elastic
  19. What happens if connective tissue is damaged?
    fibrocytes--->fibroblasts repair damage--->fibrocytes (same for chondrocytes/blasts and osteocytes/blasts)
  20. What are the differences btw fibrocytes/blasts
    • fibroblast: LCT and CT undergoing repair
    • fibrocytes: dense CT

    • both synth and secrete all major components of ECM
    • DIFF: activity level
  21. What is the job of a reticular cell?
    prod reticular fibers in hematopoietic and lymphoid tissues; phagocytize antigenic mat and cellular debris; collect Ag on surface--->activate immunocompetent cells
  22. What usually lives with reticular cells?
    lymphocytes, macrophages, FDC
  23. dense connective tissue
    fewer cells; thick matrix
  24. dense irregular connective tissue
    dense matrix is non directional
  25. dense regular connective tissue
    dense matrix is directional (i.e. tendons and ligaments)
  26. specialized CT
    • adipose tissue
    • cartilage and bone
    • lymphatic tissue
  27. What are the functions of adipose tissue?
    store energy in the form of stored lipids; cushions and insulates body
  28. What is characteristic of white adipose?
    unilocular adipose
  29. What is characteristic of brown adipose?
    multilocular adipose
  30. What is subcutaneous fat?
    • beneath skin
    • comprises "panniculus adiposus"
    • can be thicker or thinner depending on person
  31. What is intra-abdominal fat?
    in variable amts surrounding blood/lymphatic vessels in omentum and mesenteries

    located in retroperitoneal areas
  32. What is adipose tissue responsible for making?
    aromatase....makes estradiol
  33. What are some characteristics of LCT?
    • made of fibroblasts
    • support vascular channels supplying other basic tissues
  34. What cells live in LCT?
    • mast cell
    • macrophage
    • plasma cell
    • lymphocyte
    • neutrophil
    • eosinophil
    • *do not originate in LCT but migrate there once mature
  35. Mast cell
    • derived from bone marrow precursors
    • abundant basophilic granules in cytoplasm: heparin and histamine
  36. Macrophage
    • from circulating monocytes
    • phagocytic once active
    • several can fuse to become a multinucleated cell
    • lg, irregular, lg pale staining nuc
  37. Plasma cell
    • primary source of sec Ab
    • abundant in areas susceptible to invasion (GI tract)
    • lg, ovoid, eccentric nuc, abundant rER (bc sec Ab)
  38. Lymphocyte
    • present in variable numbers around body
    • sm, round cell w/ dk round nuc
  39. Neutrophil
    • migratory, phagocytic, short-lived
    • multilobed nuc
    • abundant cytoplasmic lysosomes
  40. Eosinophil
    • bilobed nuc
    • bright-red cytoplasmic granules