Endocrine and Exocrine Glands

Definition of a Gland

• A gland is a cell or an organ that secretes substances for use in the body or for elimination from the body.
• Anatomically composed of:
  • Epithelial tissue
  • Connective tissue framework and capsule

Exocrine Glands

• Characteristics:
  • Maintain contact with the body surface by a duct.
  • Duct is an epithelial tube directing secretions to the surface.
• Examples:
  • Tear glands
  • Sweat glands
  • Mammary glands
• Key Point:
  • Exocrine glands always involve a duct.

Endocrine Glands

• Characteristics:
  • Do not have contact with the body surface or cavities leading outside.
  • Lack ducts.
  • Secrete hormones directly into the blood.
• Functions:
  • Hormones act as chemical messengers.
  • Target cells exist elsewhere in the body.
  • Blood acts as the transportation medium.
• Examples:
  • Pituitary gland
  • Thyroid gland
  • Adrenal glands

Dual Function Glands

• Some organs have both endocrine and exocrine properties:
  • Liver
  • Gonads
  • Pancreas

Summary

• Understanding the difference between endocrine and exocrine glands helps in recognizing their roles in body processes.
• Exocrine glands use ducts, while endocrine glands secrete directly into the bloodstream.