Glandular Epithelium Notes

Glandular Epithelium Overview
  • Glandular epithelium is a specialized type of epithelial tissue that is responsible for secretion.
  • This type of epithelium differs from surface epithelium, which lines the internal and external structures of the body and acts as a barrier.
Types of Secretions
  • Secretions produced by glandular epithelium can be:
    • Fluids that may contain:
    • Oils
    • Proteins
    • Not to be confused with:
    • Blood or intracellular/extracellular fluids
  • Examples of secretions include:
    • Mucus
    • Gastric juices
    • Sebum (from sebaceous glands)
    • Milk
    • Sweat
Formation of Epithelial Glands
  • Epithelial glands may arise from:
    • Single epithelial cells (e.g., goblet cells in respiratory epithelium) that secrete mucus.
    • Aggregation of cells in response to higher secretion demands, forming a gland through:
    • Infolding or invagination of epithelial cells into underlying tissue layers.
    • Development of supportive connective tissue around the gland.
Modes of Secretion in Exocrine Glands
  • Secretions can have two main destinations:
    1. Lumen of an organ
    • Example: Gastric glands secrete into the gastrointestinal tract.
    1. Directly onto epithelial surfaces
    • Example: Sweat glands release sweat directly onto the skin.
Endocrine Glands
  • In contrast to exocrine glands, endocrine glands:
    • Are spread throughout the body.
    • Have a close relationship with blood vessels, allowing for hormone secretion into the bloodstream.
    • Release hormones for long-distance communication within the body.
  • They differ from exocrine glands by their method of secretion:
    • Exocrine Glands: Localized and immediate effects. (e.g., mammary, sweat, sebaceous, gastric glands)
    • Endocrine Glands: Systemic effects over longer distances.
Key Differences between Exocrine and Endocrine Glands

  • Exocrine: Secretes locally, includes glands like:

    • Mammary glands
    • Sweat glands
    • Sebaceous glands
    • Gastric glands

  • Endocrine: Secretes hormones into bloodstream, involves mechanisms like endocrine signaling, effective over long distances to target cells.