Cell Junctions and Adhesion
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Questions and Answers

What is the primary function of glandular epithelia?

  • To form sheets that cover body surfaces
  • To synthesize, store and release various products (correct)
  • To contain sensory nerve endings
  • To connect organs and systems in the body
  • What is the main characteristic of epithelial tissue?

  • It is composed of closely aggregated cells with very little extracellular substance (correct)
  • It is only found in nervous tissue
  • It is only found in muscular tissue
  • It has a lot of extracellular substance
  • What is the purpose of lining epithelia?

  • To synthesize and release products
  • To contain sensory nerve endings
  • To connect organs and systems in the body
  • To form sheets that cover body surfaces or line luminal organs (correct)
  • What is the name of the type of epithelial tissue that contains sensory nerve endings?

    <p>Special epithelia</p> Signup and view all the answers

    How many basic types of tissue are there in the body?

    <p>4</p> Signup and view all the answers

    What is the term for the aggregation of cells and extracellular substances?

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

    What is a characteristic feature of epithelial tissue?

    <p>High cellular density with little intercellular substance</p> Signup and view all the answers

    What is the term used to describe the dense sublayer of the basement membrane present between two epithelial layers?

    <p>Basal lamina</p> Signup and view all the answers

    What is the function of the basement membrane in epithelial tissue?

    <p>To act as a selective barrier between epithelium and connective tissue</p> Signup and view all the answers

    What is the orientation of epithelial cells in relation to the basement membrane?

    <p>Basal surface facing the basement membrane</p> Signup and view all the answers

    What is the significance of the basement membrane in relation to blood capillaries?

    <p>Blood capillaries never enter the epithelium across the basement membrane</p> Signup and view all the answers

    What is the characteristic of epithelial tissues subject to pressure and traction?

    <p>Marked intercellular adhesion</p> Signup and view all the answers

    What is the characteristic of simple squamous epithelium?

    <p>Flat, elongated cells with a round to oval nucleus</p> Signup and view all the answers

    Which type of epithelial tissue is found in the olfactory system?

    <p>Specific epithelium (sensory)</p> Signup and view all the answers

    What is the primary function of gap junctions in epithelial tissue?

    <p>To facilitate communication between cells through ions and small molecules</p> Signup and view all the answers

    What is the term for the lining of body cavities?

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

    What type of junctions are responsible for the cohesiveness of epithelial cells?

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

    Which type of epithelial tissue is composed of a single layer of cells?

    <p>Simple epithelium</p> Signup and view all the answers

    Where is simple squamous epithelium commonly found?

    <p>Walls of blood vessels and lymphatic vessels</p> Signup and view all the answers

    What is the function of gap junctions in epithelial tissue?

    <p>To allow cell-to-cell communication through ions and small molecules</p> Signup and view all the answers

    What is the term for the lining of body cavities?

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

    What is the characteristic feature of the stratified epithelium?

    <p>Multiple layers of cells</p> Signup and view all the answers

    What is the function of E-cadherins in epithelial tissue?

    <p>To facilitate cell adhesion</p> Signup and view all the answers

    What is the type of epithelial tissue found in the olfactory system?

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

    What is the distinctive feature of the basement membrane in epithelial tissue?

    <p>It is a selective barrier that stains prominently with PAS</p> Signup and view all the answers

    What is a characteristic of epithelial cells in terms of their blood supply?

    <p>They are avascular</p> Signup and view all the answers

    What is the term for the process by which epithelial cells adhere to each other?

    <p>Intercellular adhesion</p> Signup and view all the answers

    What is the term for the surface of epithelial cells that faces the external environment?

    <p>Apical surface</p> Signup and view all the answers

    What is the characteristic of epithelial tissues that makes them resistant to pressure and traction?

    <p>Marked intercellular adhesion</p> Signup and view all the answers

    What is the orientation of epithelial cells in relation to the basement membrane?

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

    Which of the following organs has an epithelial lining?

    <p>All of the above</p> Signup and view all the answers

    What is the function of the endothelium in the circulatory system?

    <p>Reduction of friction between blood and vessel walls</p> Signup and view all the answers

    Which type of epithelial tissue is responsible for absorbing nutrients in the small intestine?

    <p>Columnar epithelium</p> Signup and view all the answers

    What is the function of ciliated respiratory epithelium?

    <p>Cleaning by removing dust particles from air passages</p> Signup and view all the answers

    From which germ layer do epithelial cells of the gastrointestinal tract originate?

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

    What is the function of epithelial tissue in the urinary bladder?

    <p>Lining the urinary bladder</p> Signup and view all the answers

    What is the primary function of epithelial tissue in body cavities?

    <p>To form a barrier and protect underlying tissue</p> Signup and view all the answers

    Which type of epithelial tissue is responsible for specialized sensory functions?

    <p>Special epithelia</p> Signup and view all the answers

    What is the characteristic of epithelial cells in relation to extracellular substance?

    <p>They have very little extracellular substance</p> Signup and view all the answers

    What is the difference between glandular epithelia and lining epithelia?

    <p>Glandular epithelia synthesize products, while lining epithelia form a barrier</p> Signup and view all the answers

    What is the primary composition of organs and systems in the body?

    <p>A combination of four basic types of tissue</p> Signup and view all the answers

    What is the primary function of the specialized plasma membrane in the urinary bladder?

    <p>To provide an osmotic barrier between urine and tissue fluids</p> Signup and view all the answers

    What is the characteristic of epithelial cells in relation to each other?

    <p>They are closely aggregated</p> Signup and view all the answers

    Where are stem cells typically located in stratified squamous keratinized epithelium?

    <p>In the basal cell layer (stratum basale)</p> Signup and view all the answers

    What is the purpose of exfoliative cytology?

    <p>To examine cells shed from surface tissues or body liquids</p> Signup and view all the answers

    What is a criterion for classifying glandular epithelia?

    <p>All of the above</p> Signup and view all the answers

    What is the characteristic of unicellular glands?

    <p>Found in the epithelial lining of the intestine and respiratory tract</p> Signup and view all the answers

    Where can epithelial cells be constantly lost and replaced?

    <p>In all types of epithelial tissues</p> Signup and view all the answers

    What is the characteristic of simple columnar epithelium?

    <p>Single layer of columnar cells</p> Signup and view all the answers

    Which type of epithelium is found in the nasal cavity and upper respiratory tract?

    <p>Pseudostratified epithelium</p> Signup and view all the answers

    What is the characteristic of pseudostratified epithelium?

    <p>Single layer of irregularly shaped and sized cells</p> Signup and view all the answers

    What is the characteristic of stratified squamous epithelium?

    <p>Multiple layers of cells</p> Signup and view all the answers

    What is the difference between keratinized and non-keratinized stratified squamous epithelium?

    <p>Presence or absence of keratinized cells</p> Signup and view all the answers

    What is the name of the type of epithelium that lines the gall bladder?

    <p>Simple columnar epithelium</p> Signup and view all the answers

    What is the function of cilia in pseudostratified epithelium?

    <p>Movement of substances along the epithelial surface</p> Signup and view all the answers

    What is the function of goblet cells in pseudostratified epithelium?

    <p>Secretion of mucus</p> Signup and view all the answers

    What is the consequence of the absence of cilia in pseudostratified epithelium?

    <p>Increased risk of infection</p> Signup and view all the answers

    What is the characteristic of epithelial cells in stratified squamous epithelium?

    <p>Superficial cells have a squamous shape</p> Signup and view all the answers

    Study Notes

    Goblet Cells and Glandular Epithelium

    • Goblet cells have a characteristic "cup" shape due to abundant mucinogen granules at the apical end.
    • Mucinogen granules stain blue with Alcian blue, highlighting mucous production.
    • Simple columnar epithelium, containing goblet cells, lines the colon; mucin secretion aids in lubrication.
    • Multicellular glands can be classified as tubular, acinar, or alveolar based on shape and lumen size:
      • Tubular glands: straight or coiled (e.g., sweat glands, intestinal glands).
      • Acinar glands: pie-shaped with small lumen (e.g., pancreas, salivary glands).
      • Alveolar glands: larger luminal space (e.g., mammary glands).

    Epithelial Tissue Characteristics

    • Tissue organization includes cells, tissues, organs, and systems; epithelia are one of four primary tissue types (others: connective, muscular, nervous).
    • Three types of epithelium:
      • Lining (surface) epithelia cover body surfaces and line organ lumens.
      • Glandular epithelia synthesize, store, and release products (e.g., mucus, hormones).
      • Specialized epithelia contain sensor cells for sensation (e.g., taste, smell).
    • Simple columnar epithelium examples include the stomach and intestines.

    Types of Epithelia

    • Simple columnar ciliated epithelium lines the oviduct; cilia facilitate transport.
    • Pseudostratified epithelium consists of a single layer of irregular cells, all reaching the basement membrane but not the apical surface (e.g., respiratory tract).
    • Stratified squamous epithelium has multiple layers; superficial layers determine its classification as keratinized or non-keratinized.
    • Cohesiveness of epithelial cells is supported by cell junctions, including tight junctions and desmosomes.

    Intercellular Junctions

    • Three main types:
      • Tight junctions (prevent substance leakage between cells).
      • Desmosomes (provide mechanical stability).
      • Gap junctions (allow communication between cells through small channels).

    Classification of Epithelia

    • Epithelia can be classified as:
      • Simple (one layer)
      • Stratified (multiple layers)
      • Glandular (unicellular or multicellular)
    • Specific examples of simple epithelial types include:
      • Simple squamous: flat cells lining body cavities and blood vessels (mesothelium and endothelium).
      • Simple cuboidal and columnar: involved in secretion and absorption.

    Functions of Epithelial Tissues

    • Protective barriers against abrasion, pathogens, and water loss.
    • Facilitate absorption (e.g., nutrient uptake in small intestine).
    • Assist in secretion (e.g., enzymes and hormones).
    • Enable sensation through specialized receptor cells.

    Epithelial Repair and Stem Cells

    • Epithelial cells are constantly renewed; stem cells located in basal layers contribute to regeneration.
    • Shedding of surface cells occurs as new cells arise from the basement membrane.

    Clinical Relevance

    • Understanding epithelium is crucial for diagnosing glandular diseases, skin conditions, and tumors.
    • Techniques such as exfoliative cytology involve examining shed cells for diagnostic purposes.

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    Description

    This quiz covers the different types of intercellular junctions, including tight junctions, desmosomes, and gap junctions, and their functions in cell adhesion and communication.

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