Lecture 3.1

• What is epithelial tissue?

  A sheet of cells covering surfaces
• Why must substances pass through an epithelial layer?

  It covers body surfaces and lines cavities
• What are the types of epithelium?

  • Squamous
  • Cuboidal
  • Columnar
  • Stratified
  • Pseudostratified

  
• What characterizes squamous epithelium?

  Flat and thin layer for exchange

  
• Where is squamous epithelium found?

  Alveoli, kidney glomerulus, blood vessels

  
• What is the structure of cuboidal epithelium?

  Single layer with larger intracellular volume

  
• What is the function of cuboidal epithelium?

  Good for absorption and secretion

  
• Where is cuboidal epithelium located?

  Secretory glands and renal tubules

  
• What characterizes columnar epithelium?

  Single layer with absorption and secretion

  
• Where is columnar epithelium found?

  GI tract and uterine lining

  
• What defines simple epithelia?

  They consist of a single layer of cells
• What are stratified epithelia?

  They consist of multiple layers of cells
• What type of epithelial cells are keratinized?

  External areas with wear and tear

  
• What type of epithelial cells are non-keratinized?

  Internal areas with no protection needed
• What is pseudostratified epithelium?

  One layer with irregular cell heights
• How do cells in pseudostratified epithelium appear?

  They have irregularly positioned nuclei
• What do goblet cells do?

  Secrete mucus and other substances
• What is the role of the basement membrane?

  Provides metabolic support to epithelia
• What is the composition of the basement membrane?

  Mainly type IV collagen and glycoproteins
• What are the functions of the basement membrane?

  Adhesion, barrier, and cell organization
• What are cell junctions?

  Structures that connect and communicate cells
• What do occluding junctions do?

  Prevent leakage between cells
• What is the function of anchoring junctions?

  Attach cells to structural support
• What do communicating junctions allow?

  Movement of chemicals between cells

  
• What are tight and adherent junctions?

  Types of occluding junctions

  
• What are desmosomes and hemidesmosomes?

  Types of communicating junctions

  
• What is the role of gap junctions?

  Important for intracellular communication
• Where are many gap junctions found?

  In the heart
• What does it mean that epithelial cells are polarized?

  They have distinct apical and basal aspects
• Where do metabolic processes occur in epithelial cells?

  At the basal aspect
• What are exocrine glands?

  Glands that secrete products onto surfaces
• How do exocrine glands secrete their products?

  Directly onto epithelial surface or via ducts
• What are the three types of exocrine glands?

  • Merocrine
  • Apocrine
  • Holocrine

  
• How do merocrine glands release their secretions?

  Via exocytosis

  
• How do apocrine glands release their secretions?

  By shedding part of the cytoplasm
• How do holocrine glands release their secretions?

  By shedding the whole cell
• What is an example of a single exocrine cell?

  Goblet cell in the GI tract
• What forms can exocrine glands take?

  Simple or compound, tubular or acinar

  
• What is adenocarcinoma?

  Cancer of glandular epithelium
• What do endocrine glands do?

  Release secretions directly into the blood