Lecture on Skin Glands

Overview

• Focus on the various glands associated with the skin
• Two types of sweat glands: eccrine and apocrine

Eccrine Sweat Glands

• Type: Merocrine glands
  • Secrete via exocytosis
  • Cells remain intact
• Function: Primarily involved in thermal regulation
  • Sweat evaporates, cooling effect
• Distribution: Most abundant on palms, soles, and forehead
  • Sweating begins at forehead
• Structure: Simple coiled glands with ducts
  • Regulated by sympathetic nervous system
  • Myoepithelial cells: contract in response to sympathetic stimulation
• Composition of Sweat: Hypotonic
  • 99% water
  • Contains salts, vitamin C, antibodies, and dermocidin (microbe-killing peptide)
  • Limited metabolic waste (e.g., urea)
• Relevance: Interaction with pathogens on palms and soles

Apocrine Sweat Glands

• Type: Modified merocrine glands
• Location: Axillary (armpit) and anogenital area
• Function: Not for thermal regulation
  • Potential sexual scent glands
  • Secrete a thicker sweat containing fats and proteins
  • Odorless, but bacterial metabolism causes body odor
• Structure: Secrete into hair follicles
• Triggers: Pain, stress, sex hormones (androgens)
• Variations: Modified apocrine glands include ceruminous (earwax) and mammary glands (nutritional)

Sebaceous (Oil) Glands

• Distribution: Widely distributed, associated with hair follicles
  • Not found in thick skin of palms and soles
• Function: Secrete sebum
  • Lubricates hair and skin, preventing dryness
  • Contains antimicrobial peptides
• Activity: Inactive until puberty, triggered by androgens
• Structure: Holocrine origin
  • Central cell releases contents as sebum
  • Simple alveolar structure
• Issues: Overproduction leads to whiteheads and blackheads

Histological Characteristics

• Eccrine and Apocrine Glands: Cuboidal to columnar cells adapted for secretion
• Sebaceous Glands: Grape-like clusters in a simple alveolar tube