Types of Glands in the Body

Overview of Glands

• Endocrine Glands

  • Secrete hormones directly into the bloodstream.
  • Example: Hormones.

• Exocrine Glands

  • Secrete materials to a surface via ducts.
  • Examples: Mouth, nose, intestines, skin.

Functional Classification of Exocrine Glands

• Merocrine Secretion

  • Most common type.
  • Involves exocytosis: Vesicles from the Golgi apparatus fuse with the cell membrane to release materials.
  • Examples: Sweat glands.

• Apocrine Secretion

  • Vesicles released involve a part of the cell pinching off.
  • Produces thicker secretions.
  • Examples: Mammary glands, certain sweat glands.

• Holocrine Secretion

  • Entire cells are secreted.
  • Thickest type of secretion.
  • Requires rapid cell mitosis for replacement.
  • Example: Sebaceous (oil) glands.

Membranes in the Body

Types of Membranes

• Epithelial Membranes

  • Mucous Membranes
    • Line cavities opening to the outside (e.g., mouth, intestines, trachea, etc.).
    • Composed of various epithelial tissues depending on location/function.
    • Contains lamina propria (areolar connective tissue).
  • Serous Membranes
    • Line cavities that do not open to the outside (e.g., heart, lungs, abdominal organs).
    • Consist of two layers: visceral (touches organ) and parietal (lines cavity).
    • Specific names based on location (e.g., pericardium, pleura, peritoneum).
  • Cutaneous Membrane
    • Forms skin.
    • Made of keratinized stratified squamous epithelium.
    • Protects the body.

• Connective Tissue Membranes

  • Synovial Membranes
    • Found in freely movable joints.
    • Line synovial cavities.
    • Composed mainly of areolar tissue with some adipose tissue.
    • Contain synovialcytes to produce synovial fluid.