Biology: Tissues and Cell Junctions
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Questions and Answers

Which of the following is an example of a liquid tissue?

  • Muscle
  • Fat
  • Blood (correct)
  • Bone

    • Which type of junction creates a seal that prevents substances from passing between cells?

  • Desmosomes
  • Adherens junctions
  • Hemidesmosomes
  • Tight junctions (correct)

    • Which transmembrane glycoproteins are found in adherens junctions?

  • Cadherins (correct)
  • Laminin
  • Tubulin
  • Integrins

    • Which basic tissue type generates body heat and movement?

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

    Which feature is characteristic of non-ciliated simple columnar epithelium?

    <p>Elongated nuclei</p> Signup and view all the answers

    Which protein primarily composes the plaques in desmosomes?

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

    Where is pseudostratified columnar epithelium most commonly found?

    <p>Lining the upper respiratory tract</p> Signup and view all the answers

    What is the key function of intermediate filaments?

    <p>Attach cells together and stabilize organelle position</p> Signup and view all the answers

    What is the primary function of stratified squamous epithelium?

    <p>Protection against abrasion and microbes</p> Signup and view all the answers

    Which of the following scientists specialize in laboratory studies of cells and tissues for diagnoses?

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

    Which epithelial tissue type allows urinary organs to stretch and maintain a protective lining?

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

    Which cytoskeletal components are responsible for generating movement and providing mechanical support?

    <p>Actin/Myosin</p> Signup and view all the answers

    What distinguishes stratified cuboidal epithelium from other epithelial tissues?

    <p>It is usually only 2-3 cells thick.</p> Signup and view all the answers

    What is the function of goblet cells in non-ciliated simple columnar epithelium?

    <p>Secreting mucus</p> Signup and view all the answers

    Which surface of epithelial cells may contain cilia or microvilli?

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

    What is a primary function of simple squamous epithelium?

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

    Which epithelial tissue is composed of multiple layers with only the basal layer in contact with the basement membrane?

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

    Which epithelial tissue lines the kidney tubules?

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

    Which layer of the basement membrane contains laminin and collagen?

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

    Which function is NOT associated with epithelial tissues?

    <p>Storing fat</p> Signup and view all the answers

    Which type of epithelial tissue is designed for areas that experience stretching?

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

    Where is endothelium found?

    <p>Lining blood capillaries</p> Signup and view all the answers

    Which type of cartilage makes up the malleable part of the external ear?

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

    Which mature connective tissue allows stretching of tissues like the elastic arteries (aorta)?

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

    What is a characteristic feature of hyaline cartilage?

    <p>It provides a smooth surface for joint movement</p> Signup and view all the answers

    Which mature connective tissue is known for being extremely tough and making up intervertebral spaces and knee joints?

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

    Which type of cell is predominantly found in dense irregular connective tissue?

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

    What type of tissue is characterized by having a poor blood supply and slow growth?

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

    Which statement is true about fibrocartilage?

    <p>It contains thick bundles of collagen fibers and is very strong</p> Signup and view all the answers

    Which connective tissue forms most of the skeleton in the embryo?

    <p>Hyaline cartilage</p> Signup and view all the answers

    What is the primary function of glandular epithelium?

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

    Which of the following is an endocrine gland?

    <p>Thyroid gland</p> Signup and view all the answers

    Where are simple cuboidal epithelial tissues commonly found?

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

    Which type of extracellular matrix can be found in connective tissues?

    <p>Semi-fluid</p> Signup and view all the answers

    Which connective tissue cells are most numerous?

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

    Which of the following does NOT describe connective tissues?

    <p>Contains densely packed epithelial cells</p> Signup and view all the answers

    What do endocrine glands release directly into the bloodstream?

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

    What is a shared characteristic of connective tissues?

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

    Which type of connective tissue is most widely distributed in the body?

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

    Which cell type is responsible for making bone?

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

    What is the primary function of adipocytes?

    <p>Storing triglycerides</p> Signup and view all the answers

    Which type of connective tissue forms a scaffolding used by cells of lymphoid tissues such as the spleen and lymph nodes?

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

    Which type of embryonic connective tissue is found in the umbilical cord?

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

    What is the function of dense irregular connective tissue?

    <p>Providing strength when forces are pulling from many different directions</p> Signup and view all the answers

    Study Notes

    Epithelial Tissues

    • Non-ciliated simple columnar epithelium:
      • Exhibit elongated nuclei
      • Found on highly absorptive surfaces (e.g., lining of the gastrointestinal tract)
      • Microvilli increase surface area for absorption
      • Goblet cells secrete mucus
    • Ciliated simple columnar epithelium:
      • Cilia are much larger than microvilli (up to 300 per cell)
      • Cilia beat to propel fluid or material over the epithelial surface
      • Found in the lining of the fallopian tubes in the female reproductive system
    • Pseudostratified columnar epithelium:
      • Appears to have several layers, but all cells contact the basement membrane
      • Nuclei are at different levels (not columnar)
      • Ciliated variety is almost exclusive to the lining of the upper respiratory tract
    • Stratified cuboidal epithelium:
      • Thin, usually only 2-3 cells thick
      • Found in ducts of sweat glands
      • Provides protection to other tissues
      • Stratified columnar epithelium is very rare
    • Stratified squamous epithelium:
      • Keratinized variety forms the superficial layer of the skin (epidermis)
      • Non-keratinized variety lines wet surfaces (e.g., mouth, esophagus, and vagina)
      • Protects against abrasion, water loss, UV, and defense against microbes
    • Transitional epithelium:
      • Variable appearance
      • Almost exclusively lines the urinary system (e.g., bladder, ureters, and urethra)
      • Allows urinary organs to stretch and maintain a protective lining

    Epithelia vs. Connective Tissues

    • Surfaces of epithelial cells and basement membrane:
      • Apical surfaces may contain cilia or microvilli
      • Lateral surfaces may contain junctions
      • Basal surface binds to the basement membrane
    • Function of epithelia:
      • Form selective barriers
      • Provide secretory surfaces
      • Provide protective surfaces

    Classification of Epithelial Tissues

    Classified by Shape of Surface Cells

    • Squamous = flat
    • Cuboidal = cube-shaped
    • Columnar = tall column
    • Transitional = shape varies with tissue stretching (changes shape)

    Classified by Arrangement of Cells into Layers

    • Simple: One layer, all cells in contact with basement membrane
    • Pseudostratified: Appears to have layers, but all cells contact the basement membrane
    • Stratified: Two or more layers, only basal layer in contact with basement membrane

    Simple Squamous Epithelium

    • Found lining surfaces involved in passive transport (diffusion)
    • Examples: gases (lungs), liquids (walls of blood capillaries), epithelial layer of serous membranes (mesothelium), and lining of pleural, pericardial, and peritoneal cavities (visceral/parietal layers)

    Simple Cuboidal Epithelium

    • Functions in secretion and absorption
    • Usually lines small ducts and tubules
    • Examples: covers the surface of the ovary, lines kidney, salivary, and pancreatic tubules

    Basement Membrane

    • Consists of two extracellular layers:
      • Basal lamina: contains laminin and collagen
      • Reticular lamina: contains fibroblasts that secrete collagen

    Connective Tissues

    • Dense irregular connective tissue:
      • Consists predominantly of fibroblasts and freely branching elastic fibers
      • Allows stretching of certain tissues like the elastic arteries (e.g., aorta)
    • Cartilage:
      • Tissue with poor blood supply that grows slowly
      • Hyaline (glass-like) cartilage is the most abundant type
      • Covers the ends of long bones and parts of the ribs, nose, trachea, bronchi, and larynx
      • Provides a smooth surface for joint movement
    • Fibrocartilage:
      • Consists of chondrocytes located in a threadlike network of elastic fibers
      • Makes up the malleable part of the external ear and the epiglottis
    • Elastic cartilage:
      • With thick bundles of collagen fibers, is a very strong, tough cartilage
      • Supports the huge loads up and down the long axis of the body
      • Makes up the intervertebral spaces and the knee joints

    Histology

    • Histology is the science that deals with the study of tissues
    • Pathologists specialize in laboratory studies of cells and tissues for diagnoses

    Cell Junctions

    • Contact points between membranes of tissue cells
    • Five main types: tight junctions, adherens, desmosomes, hemidesmosomes, and gap junctions

    Adherens Junctions

    • Contain plaque protein which anchors membrane proteins to cytoskeleton
    • Cadherins: transmembrane glycoproteins join adjacent cells
    • Form adhesion belts around cells
    • Helps resist cells separating under mechanical stress (e.g., during peristalsis)

    Tight Junctions

    • Web-like strands of transmembrane proteins
    • Fuse together at the outer surfaces of cells
    • Seal passageways between cells
    • Found in the stomach, intestines, and bladder
    • Prevent leakage and stop substances from passing between cells

    Desmosomes and Hemidesmosomes

    Desmosomes

    • Like adherens, contain plaque protein and Cadherins
    • Plaque attaches to intermediate filaments in cells (Keratin)
    • Intermediate span cells, providing stability

    Hemidesmosomes

    • Do not link adjacent cells
    • Contain Integrin transmembrane glycoproteins (not cadherins) which attach to intermediate filaments inside cells
    • Anchor to the basement membrane by binding to Laminin

    Four Basic Tissue Types

    • Epithelial:
      • Covers body surfaces and lines hollow organs, body cavities, ducts, and forms glands
    • Connective:
      • Protects, supports, and binds organs
      • Stores energy as fat and provides immunity
    • Muscular:
      • Generates the physical force needed to make body structures move and generate body heat
    • Nervous:
      • Detects changes in the body and responds by generating nerve impulses

    Cytoskeleton

    • Network of protein filaments throughout the cytosol
    • Provides structural support for the cell
    • Three types:
      • Actin/Myosin: generates movement and mechanical support
      • Intermediate filaments: stabilize organelle position and attach cells together
      • Microtubules: hollow tubes - TUBULIN, determines cell shape, and movement of organelles and vesicles

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    Description

    Learn about the definition and types of tissues, as well as the different types of cell junctions in this biology quiz. Understand the importance of histology in diagnosing diseases.

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