the skin

• Skin


  • Provides a protective covering over the surface of the body
  • Regulates body temperature
  • Has an important role in excretion
• Even when there is no visible perspiration on the skin, the sweat glands secrete about 500 mL of water per day
• Substances dissolved in sweat


  • Sodium chloride
  • Lactic acid
  • Urea
• These substances are being excreted from the body
• Some drugs, such as salicylic acid, are also excreted by the skin
• Sweat production


  1. Sweat glands located in the lower layers of the skin

  2. Duct carries the sweat to a hair follicle or to the skin surface where it opens at a pore

  3. Cells surrounding the glands are able to contract and squeeze the sweat to the skin surface