L8

• What are the three embryonic germ layers from which epithelia arise?

  Ectoderm, mesoderm, and endoderm
• What are the classifications of epithelial tissues based on cell layers and shape?

  • Simple squamous
  • Simple cuboidal
  • Simple columnar
  • Pseudostratified ciliated columnar with goblet cells
  • Transitional
  • Stratified squamous (nonkeratinized)
  • Stratified squamous (keratinized)

  
• What is the function of simple squamous epithelium?

  It lines surfaces such as blood vessels and alveoli for diffusion.
• Where is simple cuboidal epithelium found?

  In the lining of the distal tubule in the kidney and ducts of some glands.
• What is the location of simple columnar epithelium?

  It lines the intestine, stomach, and excretory ducts of some glands.
• What type of epithelium lines the urinary passages?

  Transitional epithelium.
• What is the characteristic of stratified squamous (nonkeratinized) epithelium?

  It has flattened nucleated cells.
• Where is stratified squamous (nonkeratinized) epithelium found?

  In the lining of the esophagus, vagina, and mouth.
• What is the defining feature of stratified squamous (keratinized) epithelium?

  It has flattened cells without nuclei.
• What are the main functions of epithelial tissues?

  Transcellular transport, absorption, secretion, selective permeability, and protection.
• How does transcellular transport occur in epithelial tissues?

  Through diffusion, carrier protein-mediated transport, and vesicle-mediated transport.
• What is the role of tight junctions in epithelial tissues?


  They prevent the paracellular movement of solutes, ions, and water.
• What is the significance of desmosomes in epithelial tissues?

  They provide adhesion between epithelial cells.
• What is pemphigus vulgaris?

  It is an autoimmune skin disorder characterized by IgG antibodies against desmoglein.
• What are the symptoms of bullous pemphigoid?

  Tense blisters and less severity compared to pemphigus vulgaris.
• What are gap junctions composed of?

  They are composed of connexons made of proteins called connexins.
• How do mutations in connexin genes relate to deafness?

  Mutations in connexin genes in the cochlea can cause deafness.
• What is the basal epithelial surface?


  A supportive structure between the epithelium and the underlying connective tissue.
• What specialized structures are found on apical epithelial surfaces?

  Microvilli, stereocilia, and cilia.
• What is Kartagener syndrome?

  It is a condition characterized by immotile cilia due to a dynein arm defect.
• What are the types of glands based on their secretion methods?

  • Merocrine: Release contents by exocytosis (e.g., parotid gland)
  • Apocrine: Release part of the cell along with contents (e.g., mammary gland)
  • Holocrine: Release entire cell with contents (e.g., sebaceous gland)

  
• What are carcinomas?


  Malignant tumors that arise from epithelia.
• What is the extracellular matrix (ECM)?


  An organized meshwork of macromolecules surrounding and underlying cells.
• What are the functions of the extracellular matrix?

  It influences cell shape, migration, interactions, division, and differentiation.
• What are the components of ground substance in the ECM?

  • Glycosaminoglycans (GAGs)
  • Proteoglycans
  • Glycoproteins
• What are glycosaminoglycans (GAGs)?


  Long, unbranched polysaccharides composed of repeating disaccharide units.
• What is the role of proteoglycans in the ECM?

  They act as binding sites for growth factors and signaling molecules.
• What are glycoproteins?


  Multifunctional molecules that promote adhesion between the cell and the matrix.
• What is the most abundant structural protein of the ECM?


  Collagen.
• What is scurvy caused by?

  Deficiency of vitamin C leading to poorly hydroxylated tropocollagen.
• What is Ehlers-Danlos syndrome?


  A genetic defect in type III collagen leading to fragile skin and hyperflexible joints.
• What is Alport syndrome?


  A genetic defect in type IV collagen causing glomerulonephritis and hearing disorders.
• What are the components of elastic fibers?

  Elastin and fibrillin-1.
• What is Marfan syndrome?


  A condition caused by mutations in the gene encoding fibrillin, leading to long limbs and cardiovascular issues.
• What is the likely defect in a patient with Ehlers-Danlos syndrome?

  Defect in collagen structure.
• What is the likely defect in a patient with Alport syndrome?

  Defect in type IV collagen.
• What is the likely defect in a patient with Marfan syndrome?

  Defect in fibrillin.
• What is the likely defect in a patient with Kartagener syndrome?

  Defect in dynein arms of cilia.
• What is the likely defect in a patient with bullous pemphigoid?

  Defect in hemidesmosomes.
• What is the likely defect in a patient with pemphigus vulgaris?

  Defect in desmoglein.