Functional Classification of Exocrine Glands

Functional Classification of Exocrine Glands

• Exocrine glands are classified based on their secretion mechanisms.
• Three primary types of functional exocrine glands:
  • Merocrine
  • Apocrine
  • Holocrine

Secretory Processes

• All secretory processes initiate in the endoplasmic reticulum and golgi complex.
• These organelles collaborate to form intracellular secretory vesicles that contain the secretory product.

Merocrine Glands

• Synthesized on ribosomes attached to rough endoplasmic reticulum (ER).
• Processed and packaged by the golgi complex.
• Secretions released from the cell via exocytosis in secretory vesicles.
• Represent the majority of exocrine glands in the body.
• Examples include:
  • Salivary glands
  • Pancreas
  • Some sweat glands

Apocrine Glands

• Secretions accumulate at the apical surface of the cell.
• The apical portion pinches off through exocytosis to release the secretion.
• The cell repairs itself and can repeat the process.
• Examples include:
  • Mammary glands
  • Sweat glands located in armpits and groin

Holocrine Glands

• Secretions build up in the cytosol as cells mature.
• The entire cell ruptures to release its contents as the secretory product.
• Newly formed cells replace those that are destroyed.
• Secretes large amounts of lipids from plasma and intracellular membranes.
• Require significant cell divisions for replacement.
• Examples include:
  • Sebaceous glands of the skin
  • Associated with acne production