Skin

• The skin provides protection from damage and entry of bacteria
• Regulates temperature and acts as an excretory and sensory organ
• Physical protection from damage is mainly provided by the epidermis
• Thickness of the subcutaneous tissue plays a role in protecting against injury
• The skin acts as a barrier against microorganisms, chemicals, and ultraviolet rays
• Acts as a waterproof coat, preventing rapid absorption or evaporation of water and electrolytes
• Through perspiration, the body loses 500 ml of water a day
• Regulation of temperature is important, achieved through sweat excretion and cooling by evaporation
• Sweat consists of 95% water, 2% dissolved salts, a small amount of urea, and about 3% carbon dioxide
• Sweat helps eliminate excessive fluid and salts, maintaining the body's mineral balance
• The skin is a sensory organ with nerve endings sensitive to touch, pain, pressure, heat, cold, and itching
• Special functions of the skin include secretion of ear wax and sebum by sebaceous glands
• The skin is exposed to various injuries and infections, including bacterial, viral, fungal, and parasitic infections
• Skin cancer, like melanoma, can be triggered by excessive sun exposure
• Skin allergies and irritations by harmful chemicals can cause dermatitis or eczema
• Acne is a condition of overactivity of sebaceous glands, common in adolescence
• Psoriasis is a chronic skin disorder causing overproduction of epithelial cells
• Skin lesions are classified as primary (acne, rash, eczema, furuncle, erythema, dermatomycosis) or secondary (crusts, fissures, excoriations, ulcers)
• The skin is composed of two main layers:

  • Epidermis (thin outer layer)
  • Dermis (thicker inner layer)
• Epidermis:

  • Protective layer without blood vessels and nerves
  • Built up of flat cells of the epithelium
  • Cells reproduce rapidly in the deepest layer and move up to the surface to form a protective layer of dead cells
  • Dead cells are continually lost and replaced by new ones (keratinization process)
  • Contains pigment melanin, which gives the skin color
  • Hereditary factors determine skin color
  • Sunlight increases melanin concentration, protecting the skin from harmful ultraviolet sun rays
• In certain parts of the body, the epidermis is modified to produce hair and nails

  • Hair grows on all body surfaces except the palms of the hands and soles of the feet
• Fungal infection of skin

  dermatomycosis
• Located under the skin

  Subcutaneous layer
• A region in an organ or tissue which has suffered damage such asa wound, ulcer, abscess, tumour

  Skin lesion
• The process of turning liquid into vapour

  Evaporation
• more then is necessary, normal or desirable

  excessive
• a small, often slightly raised blemish on the skin made by dark concentration of melanin

  dark mole
• a contagious skin disease marked by itching and small raised red spots, caused by the itch mite


  scabies
• A medical condition in which patches of skin become rough and inflamed wity blisters which cause itching and bleeding

  Eczema
• an inflamed pus-filled swelling on the skin, caused typically by the infection of a hair follicle

  furuncle
• superficial reddening of the skin, usually in patches, as a result of injury or irritation causing dilatation of the

  blood capillaries

  erythema
• an open sore on an external or internal surface of the body, caused by a break in the skin or mucous membrane which fails to heal

  ulcer
• damage or removal of part of the skin surface

  excoriations
• The integumentary system consists of the skin and its associated structures
• The integumentary system protects against infection, dehydration, ultraviolet radiation, and injury
• Extensive damage to the skin, such as burns, can lead to dangerous complications
• The skin serves in temperature regulation and sensory perception
• The adjective cutaneous refers to the skin
• The epidermis is the outermost portion of the skin, consisting of 4 to 5 layers of epithelial cells
• The deepest layer of the epidermis, the stratum basale, produces new cells