1. long term resident cells
    fibroblasts - produce extracellular matrix components

    Other cells- other jobs besides producing connective tissue
  2. extracellular matrix
    -composed of fibers/fibrils and gelantinous ground substance both produced by fibroblasts
  3. ground substance
    rich in glycosaminoglycans (GAGs) and proteoglycan aggregates

    -secrete some multiadhesive glycoproteins that stablilize the matrix and aid in cell- CT interactions

    -allows diffusion of molec and access of blood borne cells
  4. GAGs
    long chain linear polysaccharides that interact with other ground substance molecules to form proteoglycans

    ex) hyaluronic acid (longer and more rigid than other examples) - increases viscosity

    -sulfate residues give neg charge making them basophilic

    -sodium ions are attracted to the neg charge and bring in water
  5. 3 parts of ground substance
    GAGs, Proteoglycans, multiadhesive glycoproteins
  6. Proteoglycans
    linear proteins with GAG side chains (look like bottle brush)

    -often attached to hyaluronic acid (GAG) through linker protein to form proteoglycan aggregates
  7. multiadhesive glycoproteins
    secreted by principal CT cells and act to stabilize ECM and link it to cell surfaces

    ex) fibronectin and laminin - play key roles in basal lamina and attaching epi. cells to underlying CT
  8. Fibrous component of CT
    secrete proteins into space around cell which become fibrils (TEM) -> fibers (LM)

    -provides tensile strength

    3 types of fibers - collagen, elastic, reticular
  9. CT classifications (general)
    1) CT proper: Loose, Dense (Reg and irreg), reticular, elastic, adipose

    • 2) Developmental CT: in embryos/newborns
    • -mesenchyme, wharton's jelly, brown adipose tissue

    • 3) Supportive CT: structural support with harder ECM
    • -Cartilage, bone

    4) Peripheral blood: special case
  10. Loose CT (general)
    highly cellular CT usually under epithelial cells

    -anchors epi. and monitors bacterial/antigenic invasion

    -cells more than type 1 collagen and elastic fibers
  11. cells of loose CT
    • Fibroblasts
    • Macrophages
    • Mast cells
    • Adipose cells
    • Plasma cells
    • Leucocytes
  12. Loose CT: Fibroblast
    principal cell type: small, varied shapes, derived from mesenchymal cells

    Function: produce matrix of type 1 collagen fibers and elastic fibers in a viscous ground substance to form the ECM

    LM appearance: elongated nucleus, thin cytoplasm

    • TEM appearance: rough ER is prominent, scalloped cell outline, thin processes seen extending from cell to collagen
    • bundles
  13. Loose CT: Macrophages
    when blood monocytes enter loose CT from blood by diapedesis

    function: resident phagocytic cells

    LM appearance: larger nuclei than fibroblasts, indented nuclear envelope, easier to recognize when phagocytosing something, phag. material may be foamy/granule looking

    TEM appearance: many lysosomes, may extend pseudopods
  14. Loose CT: Mast Cells
    precursors in bone marrow and take residence in loose CT

    • Function: promote inflammation
    • -have basophilic/metachromatic granules (heparin, histamine, tryptase, eosinophil chemotactic factor)
    • -has cell surface receptors for IgE with IgE bound -> Ag binds, Ca2+ channels open
    • -after granule release, plasma membrane releases leukotrienes

    LM appearance: near blood vessels, nonlobulated/ovoid nucleus, granules can stain intensely basophilic

    TEM appearance: large cytoplasmic granules (dark)
  15. Loose CT: Adipose cells
    Large cell with glycogen, A large fat inclusion, thin rim of cytoplasm, has external lamina

    Functions: store energy, secrete weight control factors, convert precursor hormones

    LM appearance: washed out, eccentrically flattened nucleus, cell looks like signet ring
  16. Plasma cells
    from Bcells in connective tissue and enter the CT

    Function: secretes proteins and each secretes a specific antibody

    LM appearance: homogenous basophilic cytoplasm, clumps of heterochromatin (clock face/wagon wheel appearance)

    TEM appearance: lots of rER, marginated heterochromatin with clock face appearance
  17. leucocytes
    enter CT from blood (granulocytes like basophils etc and agranulocytes like Tcells, Bcells, and monocytes)

    function: promote immune response to parasites, Ag, or bacteria
  18. ECM
    produced by fibroblasts and consists of Type 1 collagen fibers and elastic fibers in a viscous ground substance

    • Function: allows for nutrient metabolic product diffusion to the blood, allows movement of leucocytes into the CT and
    • retards bacterial movement
Card Set
connective tissue proper and cartilage