Ona: Week 3

• What is the definition of tissue?

  A group of cells that usually have a common origin in an embryo and function together to carry out specialized activities.
• How do tissues contribute to homeostasis?

  By providing diverse functions including protection, support, communication among cells, and resistance to disease.
• What are the four basic types of tissue?

  1. Epithelial tissue
  2. Connective tissue
  3. Muscular tissue
  4. Nervous tissue
• What is the primary function of epithelial tissue?

  It covers body surfaces, lines body cavities, hollow organs and ducts, and forms glands.
• What is the role of connective tissue?

  To protect and support the body and its organs, bind organs together, store energy reserves as fat, and help provide immunity to disease-causing organisms.
• What is the function of muscular tissue?

  It contracts to make body parts move and generates heat.
• What does nervous tissue do?

  It carries information from one part of the body to another through electric signals called nerve impulses.
• What is histology?

  The science that deals with the study of tissues.
• Who is a pathologist?

  A physician who specializes in laboratory studies of cells and tissues to help other physicians make accurate diagnoses.
• What is a principal function of a pathologist?

  To examine tissues for any changes that might indicate disease.
• What are cell junctions?

  Contact points between the plasma membranes of tissue cells.
• What are the five types of cell junctions?

  1. Tight junctions
  2. Adherens junctions
  3. Desmosomes
  4. Hemidesmosomes
  5. Gap junctions
• What do tight junctions do?

  They seal off passageways between adjacent cells and inhibit the passage of substances.
• What is the function of adherens junctions?

  They help epithelial surfaces resist separation during various contractile activities.
• What are desmosomes primarily used for?

  To prevent epidermal cells from separating under tension and cardiac muscle cells from pulling apart during contraction.
• What do hemidesmosomes do?

  They anchor cells to the basement membrane rather than linking adjacent cells.
• What is the role of gap junctions?

  They enable nerve or muscle impulses to spread rapidly among cells for cell-to-cell communication.
• What is epithelial tissue composed of?

  Cells arranged in continuous sheets, in either single or multiple layers.
• What are the functions of epithelial tissue?

  They act as selective barriers, secretory surfaces, and protective surfaces.
• What are the three surfaces of epithelial tissue and their functions?

  1. Apical (free) surface – receives cell secretions; may contain cilia or microvilli.
  2. Lateral surface – contains the cell junctions.
  3. Basal surface – adheres to extracellular matrix such as the basement membrane.
• What are the types of epithelial tissue?

  1. Covering and lining epithelium
  2. Glandular epithelium
• What is the arrangement of simple epithelium?

  It is a single layer of cells that functions in diffusion, osmosis, filtration, secretion, or absorption.
• What is pseudostratified epithelium?

  It appears to have multiple layers of cells because the cell nuclei lie at different levels.
• What is the function of stratified epithelium?

  To protect underlying tissues in locations where there is considerable wear and tear.
• What are squamous cells?

  Thin cells that allow for the rapid passage of substances through them.
• What are cuboidal cells?

  Cells that are as tall as they are wide and may have microvilli at their apical surface, functioning in secretion or absorption.
• What are columnar cells?

  Cells that are much taller than they are wide, protecting underlying tissues and often specialized for secretion and absorption.
• What are transitional cells?

  Cells that change shape from squamous to cuboidal and back as organs stretch and collapse.
• What are the types of simple epithelium?

  1. Simple squamous epithelium
  2. Simple cuboidal epithelium
  3. Simple columnar epithelium (non-ciliated and ciliated)
  4. Pseudostratified columnar epithelium (non-ciliated and ciliated)
• What are the types of stratified epithelium?

  1. Stratified squamous epithelium (keratinized and non-keratinized)
  2. Stratified cuboidal epithelium
  3. Stratified columnar epithelium
  4. Transitional epithelium
• What is simple squamous epithelium?


  A single layer of flat cells that lines structures such as the heart, blood vessels, and air sacs of lungs.
• What is the function of simple cuboidal epithelium?

  It functions in secretion and absorption and covers surfaces such as the ovary and kidney tubules.
• What is ciliated simple columnar epithelium?

  A single layer of ciliated column-like cells that moves mucus and other substances by ciliary action.
• What is non-ciliated simple columnar epithelium?

  A single layer of non-ciliated column-like cells that functions in secretion and absorption.
• What is pseudostratified columnar epithelium?

  It is not a true stratified tissue; all cells are attached to the basement membrane but not all reach the apical surface.
• What is the function of stratified squamous epithelium?

  To protect underlying tissues in areas subject to abrasion.
• What is keratinized stratified squamous epithelium?

  It has surface cells that are dead and become hardened.
• What is non-keratinized stratified squamous epithelium?

  It has surface cells that remain alive and moist.
• What is stratified cuboidal epithelium?

  It consists of two or more layers of cube-shaped cells.
• What is stratified columnar epithelium?

  It consists of several layers of cells with cuboidal shape in deep layers and columnar shape in apical layers.