Unit 7: Connective Tissue
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Questions and Answers

What is the primary component of elastic fibers that provides elasticity in connective tissue?

  • Keratin
  • Collagen
  • Elastin (correct)
  • Fibrillin

    • Which cell type is considered the active form of fibroblasts?

  • Pericyte
  • Fibroblast (correct)
  • Mast cell
  • Fibrocyte

    • What structural feature of fibroblasts is observed under an electron microscope?

  • Abundant rough endoplasmic reticulum (correct)
  • Granular cytoplasm
  • Scant cytoplasm
  • Mitochondria predominance

    • What fibers provide the predominant structural support in connective tissue?

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

    What is the main characteristic of fibrocystic cells when viewed microscopically?

    <p>Not granular, intensely basophilic nucleus</p> Signup and view all the answers

    Which of the following is NOT a component of the extracellular matrix (ECM) in connective tissue?

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

    Which type of fiber appears yellowish in large quantities when viewed macroscopically?

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

    What are the two main components of elastic fibers?

    <p>Elastin and fibrillin microfibrils</p> Signup and view all the answers

    What is the primary function of connective tissue?

    <p>Joining together and supporting other tissues</p> Signup and view all the answers

    Which germ layer gives rise to mesenchymal connective tissue?

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

    Which of the following is NOT classified as a specialized connective tissue?

    <p>Loose connective tissue</p> Signup and view all the answers

    What type of connective tissue provides thermal regulation in the body?

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

    Which component of the extracellular matrix provides resistance to compression forces?

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

    What type of connective tissue is characterized by structural diversity and includes various types such as loose and dense connective tissues?

    <p>Connective tissue proper</p> Signup and view all the answers

    Which of the following is a function of connective tissue related to immune response?

    <p>Defense and protection</p> Signup and view all the answers

    Collagen fibers primarily provide which of the following properties to connective tissue?

    <p>Resistance to traction forces</p> Signup and view all the answers

    What are the repeating units that make up Glycosaminoglycans (GAGs)?

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

    Which of the following types of GAGs are known to be sulfated?

    <p>Dermatan sulfate</p> Signup and view all the answers

    What is the primary function of proteoglycans in the ground substance?

    <p>Storing growth factors</p> Signup and view all the answers

    Which adhesive glycoprotein is known for connecting extracellular matrix components to integrins?

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

    What distinguishes collagen fibers under a light microscope stained with H&E?

    <p>Bright white color</p> Signup and view all the answers

    Which type of collagen fibers is known as reticulin fibers?

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

    What property of GAGs contributes to their function as physical barriers?

    <p>Hydrophilic nature</p> Signup and view all the answers

    What is the diameter of collagen fibers observed under a light microscope?

    <p>10 μm</p> Signup and view all the answers

    Which staining technique is commonly used to visualize reticular fibers?

    <p>Silver stain</p> Signup and view all the answers

    What is the role of adhesive glycoproteins in the extracellular matrix?

    <p>Facilitate cell attachment and communication</p> Signup and view all the answers

    What is a distinguishing feature of unilocular adipocytes?

    <p>Have triglycerides in a single large droplet</p> Signup and view all the answers

    Which cell type is known for its contractile activity and is often found in healing areas?

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

    What is the primary function of mast cells?

    <p>Immediate hypersensitivity reaction</p> Signup and view all the answers

    What is a characteristic feature of multilocular adipocytes?

    <p>Numerous small lipid droplets</p> Signup and view all the answers

    Which cell type is part of the mononuclear phagocytic system?

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

    What is the main role of fibroblasts and fibrocytes in connective tissue?

    <p>Production of connective tissue fibers</p> Signup and view all the answers

    How do macrophages contribute to inflammation?

    <p>They release cytokines as signaling molecules.</p> Signup and view all the answers

    Which cells are involved in controlling vascular permeability?

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

    What is NOT characteristic of adipocytes?

    <p>Have thick cell walls</p> Signup and view all the answers

    Study Notes

    Connective Tissue I

    • Connective tissue is a major tissue type used to support and connect other tissues.
    • It forms a continuity of the body and maintains integration.
    • It demonstrates morphological, topographic, and structural diversity.
    • The term "connective" means "joining together."
    • Connective tissue supports and connects other tissues.

    Connective Tissue: Introduction - Embryonic Origin

    • Connective tissue arises from mesoderm, the middle germ layer.
    • Mesenchymal cells are the primary cells differentiating into specialized connective tissues.
    • Mesenchymal cells are undifferentiated cells in the mesoderm layer that give rise to different connective tissues.

    Connective Tissue: Classification

    • Embryonic connective tissue includes mesenchymal and mucous connective tissue.
    • Connective tissue proper includes loose (areolar), dense (regular and irregular), reticular, and adipose tissues.
    • Specialized connective tissues include cartilage, bone, and blood.

    Connective Tissue: Functions

    • Connective tissue connects all four tissue types.
    • It provides structural support (bones, cartilage, ligaments, tendons, capsules, and stroma).
    • It regulates temperature (adipose tissue).
    • It exchanges nutrients and waste products.
    • It defends, protects, and repairs the body (phagocytic cells, immunocompetent cells, pharmacological substances, and physical barriers).
    • Fat stores energy.

    Connective Tissue: Components - Extracellular Matrix (ECM)

    • The ECM is composed of ground substance and fibers.
    • The proportion of components varies in different connective tissues.
    • Cells are also components, varying in type and proportion depending on the tissue.

    Connective Tissue: Components - Extracellular Matrix (ECM) - Ground Substance

    • Hydrated, gel-like material.
    • Provides resistance to compression forces.
    • Contains glycosaminoglycans (GAGs), proteoglycans (PGs), and adhesive glycoproteins.
      • GAGs are long polysaccharides with repeating disaccharide units (amino sugar + uronic acid).
      • GAGs are often sulfated (negatively charged), retaining liquid and acting as a physical barrier.
      • Examples include keratin sulfate, heparan sulfate, chondroitin sulfate, dermatan sulfate, and heparin.
      • Hyaluronic acid is a type of GAG that is not sulfated.
      • Proteoglycans are GAGs bound to core proteins. Aggregates of proteoglycans with hyaluronic acid are important for tissue structure, especially in cartilage.
      • Adhesive glycoproteins bind ECM components together and to cells; examples include fibronectin, laminin, entactin, tenascin, chondronectin, and osteonectin.

    Connective Tissue: Components - Extracellular Matrix (ECM) - Fibers

    • Collagen fibers: Most abundant and present in most connective tissues.
      • Macroscopically: bright white.
      • Microscopically: 10 μm in diameter, organized in bundles. H&E stains collagen pink.
      • Van Gieson stain and light green techniques can also be used to distinguish collagen.
      • Electron microscopy reveals cross-banding at regular intervals (67 nm).
      • Types of collagen (I, II, III, IV, V) exist and perform different functions in different tissues (dermis, tendons, bone, hyaline cartilage, etc).
    • Reticular fibers: Thin, branching collagen fibers forming a flexible mesh.
      • Stained with silver techniques and PAS.
      • Important in organs and tissues.
    • Elastic fibers: Provide elasticity to tissues.
      • Macroscopically: yellowish.
      • Microscopically: acidophilic, shiny, wavy bundles.
      • Composed of elastin (central amorphous material) and fibrillin microfibrils.

    Connective Tissue: Cells

    • Connective tissue cells are categorized as fixed or resident and transient or immigrant cells.
    • Fixed/Resident cells: include fibroblasts, pericytes, fat cells, mast cells, and macrophages.
    • Transient/Immigrant cells: include plasma cells, lymphocytes, neutrophils, eosinophils, basophils, monocytes, and some macrophages.

    Connective Tissue: Cells - Fibroblasts and Fibrocytes

    • Fibroblasts are the most abundant in connective tissue.
    • Derived from mesenchymal cells.
    • Synthesize most of the ECM (collagen, elastin, ground substance)
    • Fibrocytes are the resting form of fibroblasts; less active in synthesis.

    Connective Tissue: Cells - Pericytes

    • Spindle-shaped cells with cytoplasmic processes.
    • Partially surround endothelial cells of capillaries and small venules.
    • Have contractile activity.

    Connective Tissue: Cells - Fat Cells/Adipocytes

    • Synthesize and store triglycerides.
    • Two types:
      • Unilocular adipocytes (white fat): single, large fat droplet.
      • Multilocular adipocytes (brown fat): multiple small fat droplets, abundant mitochondria.

    Connective Tissue: Cells - Mast Cells

    • Originate in bone marrow.
    • Ovoid shape, variable size, with basophilic granules.
    • Contain heparin (anticoagulant) and histamine (vasodilator).
    • Involved in immediate hypersensitivity reactions (allergies).

    Connective Tissue: Cells - Macrophages

    • Macrophages are derived from monocytes in the blood, and are a part of the mononuclear phagocytic system.
    • Phagocytic; responsible for removing foreign materials and debris.
    • Present antigens to lymphocytes, and release signaling molecules.
    • Function in chronic inflammation (epithelial cells formation, foreign body giant cells)

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    Connective Tissue I PDF

    Description

    This quiz covers the essential concepts of connective tissue, including its functions, classifications, and embryonic origins. Explore the different types of connective tissues such as loose, dense, and specialized tissues. Perfect for students looking to deepen their understanding of this critical tissue type.

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