Cell Biology and Immunology Quiz
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Questions and Answers

What is the main function of fibroblasts?

  • Cause vasodilation and increased vascular permeability
  • Engulf foreign particles
  • Release histamine and proteases
  • Produce and secrete extracellular matrix components (correct)

    • Which cell type is involved in phagocytosis and engulfing foreign particles?

  • Macrophages (correct)
  • Mast cells
  • Quiescent fibroblasts
  • Fibroblasts

    • Which cell type releases mediators such as histamine and proteases?

  • Mast cells (correct)
  • Macrophages
  • Quiescent fibroblasts
  • Fibroblasts

    • What distinguishes quiescent fibroblasts from active fibroblasts?

    <p>Less active components and less cytoplasm</p> Signup and view all the answers

    Which cell type plays a role in the inflammatory response by releasing mediators?

    <p>Mast cells</p> Signup and view all the answers

    What is the characteristic feature of mast cells?

    <p>Granules containing mediators such as histamine and proteases</p> Signup and view all the answers

    What is the main function of connective tissue?

    <p>Providing and maintaining shape and firmness in the body</p> Signup and view all the answers

    Which of the following is NOT a component of connective tissue matrix?

    <p>Adipose cells</p> Signup and view all the answers

    What is the role of proteoglycans in the ground substance of connective tissue?

    <p>Filling the spaces between collagen and elastic fibers</p> Signup and view all the answers

    Which component exceeds the volume of cells in all types of connective tissue?

    <p>Ground substance</p> Signup and view all the answers

    What is the main function of plasma cells?

    <p>Producing antibodies that mediate immunity</p> Signup and view all the answers

    What is the primary function of eosinophils in the immune response?

    <p>Phagocytosing parasites</p> Signup and view all the answers

    Which leukocytes migrate from the bloodstream into tissues through diapedesis?

    <p>Eosinophils</p> Signup and view all the answers

    Which is the most abundant type of collagen in the human body?

    <p>Collagen I</p> Signup and view all the answers

    What is the characteristic periodicity of collagen fibrils?

    <p>64 nm</p> Signup and view all the answers

    What is the main content of basophilic granules in eosinophils?

    <p>Basic proteins</p> Signup and view all the answers

    Which cells are involved in mediating inflammation and inactivating histamines and leukotrienes?

    <p>Eosinophils</p> Signup and view all the answers

    What is the role of plasma cells in the immune response?

    <p>Producing antibodies that mediate immunity</p> Signup and view all the answers

    How are collagen fibrils formed?

    <p>Through polymerization into microfibrillar units</p> Signup and view all the answers

    What type of protein provides strength and structure to various tissues in the body?

    <p>Structural proteins</p> Signup and view all the answers

    What constitutes the most common protein in the human body?

    <p>Collagen I</p> Signup and view all the answers

    What are plasma cells involved in producing?

    <p>Antibodies</p> Signup and view all the answers

    What provides structure to the mesentery?

    <p>Collagen fibers</p> Signup and view all the answers

    In polarizing microscopy, what color are collagen bundles observed as in superimposed regions?

    <p>Dark</p> Signup and view all the answers

    Which type of staining procedure makes elastic fibers appear darker?

    <p>Other than H&amp;E</p> Signup and view all the answers

    What are elastic fibers formed by before accumulating elastin?

    <p>Small glycoprotein microfibrils</p> Signup and view all the answers

    What is the high-viscosity substance that fills the spaces between cells and fibers in connective tissue?

    <p>Ground substance</p> Signup and view all the answers

    How is the ground substance revealed in electron micrographs?

    <p>As a fine granular material among collagen and elastic fibers</p> Signup and view all the answers

    What are proteoglycans composed of?

    <p>A core protein and covalently bound glycosaminoglycans (GAGs)</p> Signup and view all the answers

    What are GAGs?

    <p>Linear polysaccharides made up of repeating disaccharide units</p> Signup and view all the answers

    What is the structure of proteoglycans?

    <p>A central protein to which GAGs are covalently bound</p> Signup and view all the answers

    What distinguishes glycoproteins from proteoglycans?

    <p>Globular protein molecules with covalently attached branched chains of monosaccharides</p> Signup and view all the answers

    What is the main component of collagen fibers?

    <p>Type I collagen</p> Signup and view all the answers

    What is the main function of elastin fibers?

    <p>Supporting collagen fibers</p> Signup and view all the answers

    How are elastin cross-links formed?

    <p>Through covalent reactions between lysine residues</p> Signup and view all the answers

    Which type of collagen forms reticular fibers?

    <p>Type III collagen</p> Signup and view all the answers

    What initiates the degradation of collagen fibers?

    <p>Collagenases</p> Signup and view all the answers

    What is the rate of turnover for stable collagen in tendons, ligaments, and periodontal ligaments?

    <p>Low turnover rate</p> Signup and view all the answers

    What process allows for the assembly of collagen fibrils?

    <p>Cleavage of proteases to form tropocollagen</p> Signup and view all the answers

    What is the general composition of elastin?

    <p>High proportion of glycine, proline, and two unusual amino acids</p> Signup and view all the answers

    What is the structure of elastin?

    <p>Globular molecule that polymerizes to form elastin, an amorphous rubber-like glycoprotein</p> Signup and view all the answers

    Study Notes

    • Collagen fibrils are assembled with a regular, overlapping pattern, resulting in cross striations with alternating dark and light bands in electron microscopy.
    • Collagen fibrils are linked together to form larger collagen fibers visible by light microscopy.
    • Collagen fibers form larger aggregates, typically of Type I collagen, which are bundled and linked together by other collagens.
    • Collagen synthesis in RER involves the formation of polypeptide chains, injection as preprocollagen, and subsequent hydroxylation and glycosylation to form procollagen.
    • The removal of signalling sequences from procollagen results in procollagen, which is then transported out of the cell.
    • Procollagen is cleaved by proteases to form tropocollagen, allowing for the assembly of collagen fibrils.
    • Collagen fibrils spontaneously aggregate to form fibers, and fibers are further reinforced by covalent cross-links between tropocollagen molecules.
    • Collagen turnover is generally a slow process, with stable collagen in tendons, ligaments, and periodontal ligaments having a low turnover.
    • Degradation of collagen fibers can be initiated by collagenases, which remove the original tropocollagen peptides and allow for further degradation by normal proteases.
    • Collagen fibers are often organized into bundles in various parts of the body.
    • Collagen fibers are mainly composed of Type I collagen, which is visible as acidophilic fibers in connective tissues.
    • Type III collagen forms reticular fibers, which are much thinner (0.5 to 2 µm) and form a loose network in various tissues such as smooth muscles, endoneurium, and blood-forming organs.
    • Elastic fibers are composed of three types of fibers: oxytalan, elaunine, and elastin.
    • Elastin cross-links are formed through covalent reactions between lysine residues, resulting in desmosine and isodesmosine.
    • Elastin fibers are not elastic on their own, but oxytalan fibers form a network that supports elastin, allowing for its elastic properties.
    • Elastic fibers stretch easily due to the different ratio of microfibrils to elastin, which is adapted to the local tissue requirements.
    • Elastin is a globular molecule that polymerizes to form elastin, an amorphous rubber-like glycoprotein.
    • Elastin is made up of a high proportion of glycine, proline, and two unusual amino acids: desmosine and isodesmosine.
    • Elastin fibers have a high turnover in areas such as the arterial wall.
    • Deficiencies in collagen type III can result in the rupture of the arterial wall.

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