Epithelial Tissue Overview
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Questions and Answers

What type of secretion is characteristic of mucous glands?

  • Liquid that contains enzymes
  • Fluid that is low in viscosity
  • Thick paste-like substance
  • Viscous thick secretion (correct)

    • Which statement correctly describes serous glands?

  • They are larger in diameter than mucous glands
  • They secrete both mucous and serous secretions
  • They predominantly secrete a watery secretion (correct)
  • They contain large lumens

    • What distinguishes mixed (seromucous) glands from purely mucous or serous glands?

  • They are smaller than serous glands
  • They have no apical secretory component
  • They have a single type of secretion
  • They contain both mucous and serous acini (correct)

    • What is the role of myoepithelial cells?

    <p>To assist in the contraction of secretory units</p> Signup and view all the answers

    What type of epithelium is modified to receive sensations and includes taste buds?

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

    What is the primary characteristic of the apical surface specialization known as kinocilia?

    <p>Mobile structures covered by plasma membrane</p> Signup and view all the answers

    Which layer is the basal surface of epithelial cells associated with?

    <p>Basement membrane</p> Signup and view all the answers

    Which describes the characteristic cytoplasm of serous acini?

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

    What is the primary characteristic of epithelial tissue?

    <p>Composed mainly of cells</p> Signup and view all the answers

    Which type of epithelium is composed of a single layer of flat cells?

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

    What structure supports epithelial tissue?

    <p>Basement membrane</p> Signup and view all the answers

    What type of epithelium performs secretory functions?

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

    Which of the following types of epithelial tissue is classified as having multiple layers?

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

    What characteristic primarily distinguishes simple epithelial tissues?

    <p>Consists of one cell layer</p> Signup and view all the answers

    What type of cells are found in simple cuboidal epithelium?

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

    Which type of epithelial specialization includes junctions between cells?

    <p>Lateral cell specializations</p> Signup and view all the answers

    What is the primary function of cilia in epithelial cells?

    <p>To sweep fluid from the surface of cell sheets</p> Signup and view all the answers

    What is the structure that forms the foundation for cilia?

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

    How do occludens (tight) junctions function?

    <p>They fuse cell membranes to close the intercellular space</p> Signup and view all the answers

    What type of junction is characterized by channels that allow communication between cells?

    <p>Gap junctions</p> Signup and view all the answers

    What protein is primarily responsible for forming the structure of cilia?

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

    Which type of junctions has a belt-like structure that encircles cells?

    <p>Adherens junctions</p> Signup and view all the answers

    What type of protein is occludin associated with?

    <p>Membrane fusion protein</p> Signup and view all the answers

    Which structure increases the surface area for absorption in the small intestine?

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

    What type of epithelium is characterized by a single layer of columnar cells with a height that exceeds their width?

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

    Where is pseudostratified columnar epithelium primarily found?

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

    What distinguishes endocrine glands from exocrine glands?

    <p>Endocrine glands have no ducts</p> Signup and view all the answers

    Which type of epithelium has multiple layers with the outermost layer being keratinized?

    <p>Stratified squamous keratinized</p> Signup and view all the answers

    Which type of gland consists of a single cell?

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

    What is the main function of glandular epithelium?

    <p>Secretory function</p> Signup and view all the answers

    Where is stratified squamous non-keratinized epithelium commonly found?

    <p>In the oral cavity</p> Signup and view all the answers

    What type of exocrine gland is formed only of one cell?

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

    Study Notes

    Epithelial Tissue

    • Epithelium is a tissue composed mainly of cells with little intercellular substance, covering or lining the organs of the body or performing secretory functions.
    • Epithelium covers surfaces, lines cavities, lies on a basement membrane, is avascular (no blood vessels), but nerves can pass inbetween the cells.
    • Epithelium is continuously renewed and replaced.

    Covering Epithelium

    • Simple epithelium is formed of a single layer of cells resting on the basement membrane.
      • Simple squamous epithelium: formed of one layer of flat cells, lining blood vessels (endothelium) and lung alveoli.
      • Simple cubical epithelium: formed of a single layer of cube-shaped cells with a single rounded central nucleus, found in the thyroid gland.
      • Simple columnar epithelium: formed of a single layer of columnar cells taller than wide, with a single, basal oval nucleus, found in the stomach and small intestine.
      • Pseudostratified columnar epithelium: a single layer of cells with varying heights that all rest on the basement membrane, giving the appearance of multiple layers; found in the trachea.
    • Stratified epithelium has two or more layers of cells.
      • Stratified squamous non-keratinized epithelium: basal cells are columnar, intermediate cells are polygonal, and thin squamous cells at the surface; found in wet surfaces of openings leading to the skin (oral cavity, tongue, esophagus).
      • Stratified squamous keratinized epithelium: similar to the non-keratinized type, but the top layer is covered by tough keratin, found in the epidermis of the skin.

    Glandular Epithelium

    • Glandular epithelium performs secretory functions.
    • Exocrine glands: cells connected to the surface by a duct, with secretions transported through the duct.
    • Endocrine glands: cells lose connection to the surface, with no ducts; secretions are transported by blood.
    • Unicellular glands: formed of a single cell, e.g. goblet cells in the trachea.
    • Multicellular glands: formed of multiple cells, e.g. salivary glands.

    Exocrine Glands

    • Goblet cells: unicellular exocrine glands, shaped like a flask with a slender base and expanded apex due to mucous granules; contain a basal nucleus, rER, and Golgi complex.

    Apical Surface Specializations

    • Cilia: hair-like mobile structures covered by plasma membrane containing microtubules.
      • Basal body: base of the cilium.
      • Shaft (axoneme): contains nine pairs of microtubules surrounding two central microtubules (9+2 pattern); dynein protein in pairs of arms is responsible for cilia movement.
      • Function: sweep fluid from the surface of cell sheets in a direction.
      • Found in: epithelium lining the respiratory tract.
    • Microvilli: finger-like projections of the apical cell membrane containing actin microfilaments.
      • Function: increase surface area for absorption.
      • Found in: absorptive columnar cells lining the small intestine.

    Lateral Surface Specialization

    • Cell junctions: hold cells together and provide communication pathways.
      • Occludens (tight) junctions: membrane fusions that prevent flow of material between cells (paracellular transport).
      • Adherens (anchoring) junctions: sites of adhesions, hold cells together.
        • Zonula adherens (belt desmosomes): a belt surrounding the entire perimeter of the cell; intercellular space filled with glycoproteins (cadherin).
        • Macula adherens (desmosomes): circular or spot-like adherent junctions; intercellular space occupied by desmoglein and desmocollin (members of cadherin family); found in stratified squamous epithelium (epidermis).
      • Communicating (gap) junctions: channels for communication between cells; space between two cells crossed by multiple channels called connexons, containing connexin protein.

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    Lecture 3- Epithelial Tissue PDF

    Description

    This quiz explores the different types of epithelial tissues, their structures, and functions. It covers aspects like simple squamous, cubical, and columnar epithelium, along with their locations in the body. Test your understanding of how these tissues play vital roles in covering and lining organs.

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