Integumentary System and Skin Disorders Notes

Body Membranes

• Thin sheets of tissue that:
  • Cover body surfaces
  • Line body cavities
  • Form protective sheets around organs

Types of Body Membranes

1. Cutaneous (Skin):

   • Dry membrane
   • Outermost protective boundary
   • Epidermis: Composed of keratinized stratified squamous epithelium
   • Dermis: Mostly dense (fibrous) connective tissue

2. Mucous Membranes:

   • Moist membranes lining all body cavities that open to the exterior
   • Adapted for absorption or secretion
   • Varying types of surface epithelium:
     • Stratified squamous (mouth, esophagus)
     • Simple columnar (rest of digestive tract)
   • Underlying loose connective tissue

3. Serous Membranes:

   • Lines open body cavities closed to the exterior
   • Surfaces are simple squamous epithelium
   • Occur in pairs separated by serous fluid
     • Visceral Layer: Covers organ
     • Parietal Layer: Lines wall of body cavity
   • Examples:
     • Peritoneum (abdominal cavity)
     • Pleura (around lungs)
     • Pericardium (around heart)

4. Synovial Membranes:

   • Loose areolar connective tissue
   • Lines fibrous capsules surrounding joints
   • Secretes lubricating fluid for cushioning during movement

Integumentary System

• Consists of the:
  • Skin (cutaneous membrane)
  • Skin appendages (sweat glands, oil glands, hair, nails)

Functions of the Integumentary System

• Insulation and cushioning of deeper organs
• Protects from:
  • Mechanical damage (bumps and cuts)
  • Chemical damage (acids and bases)
  • Thermal damage (heat/cold)
  • Ultraviolet radiation (UV)
  • Microbes (bacteria)
  • Desiccation (drying out)
• Regulation of body temperature and excretion of waste
• Synthesizes Vitamin D

Structure of the Skin

• Composed of two main tissue types:
  1. Epidermis:
  • Outer layer, capable of being hard and tough
  • Stratified squamous epithelium with keratinocytes producing keratin
  • Avascular; contains melanin
  1. Dermis:
  • Dense connective tissue containing blood vessels and glands
• Hypodermis (subcutaneous layer):
  Not part of the integumentary system; mainly adipose tissue that anchors skin to organs

Appendages of the Skin

• Sebaceous (Oil) glands:

  • Produce sebum to lubricate and soften skin
  • Activate at puberty

• Sweat Glands:

  • Eccrine:
  • Regulate body temperature via sweat secretion
  • Apocrine:
  • Limited role in temperature regulation; found in axillary and genital areas

• Hair: Produced by hair follicles; consists of keratinized cells and contains melanocytes

• Nails: Hardened skin derivations; colorless due to lack of pigment

Skin Assessment

• Skin Color Changes:
  • Erythema: Redness from various causes
  • Pallor: Paleness indicating stress or anemia
  • Jaundice: Yellow tint from liver issues
  • Cyanosis: Blue discoloration indicating oxygen deprivation
• Skin Turgor:
  • Tests hydration; skin folds should flatten quickly if hydrated
• Lesions:
  • Types include plaque, vesicle, scale, crust, wheal, cyst, fissure, ulcer

Pressure Ulcers

• Happens when blood supply to skin is compromised
• Common in bedridden patients; first sign is paleness at pressure points that redden upon release

Infectious Skin Disorders

Fungal Infections:

• Tinea: Group of fungal diseases characterized by itchy lesions

Bacterial Infections:

• Boils & Carbuncles: Infections that occur in hair follicles and sebaceous glands
• Impetigo: Contagious infection causing vesicular lesions
• Cellulitis: Deeper skin infections leading to pain, redness, and potential systemic spread

Viral Infections:

• Herpes Simplex: Causes cold sores and genital herpes
• Shingles: Reactivation of chickenpox virus leading to painful rashes

Inflammatory Skin Disorders

• Acne: Caused by blocked hair follicles
• Psoriasis: Autoimmune condition with excessive skin cell production
• Eczema: Chronic condition involving a compromised skin barrier leading to inflammation
• Contact Dermatitis: Allergic reactions to irritants
• Urticaria (Hives): Increased histamine leading to itchy welts

Parasitic Infections

• Scabies: Caused by mites leading to itching and rash
• Lice: Infestation affecting hair and body

Skin Cancer

• Basal Cell Carcinoma (BCC): Common, least aggressive skin cancer
• Squamous Cell Carcinoma (SCC): More aggressive, can metastasize
• Malignant Melanoma: Most dangerous form, can spread aggressively; use ABCDE rule for detection

Developmental Changes of Skin

• Skin is thicker and more hydrated in youth, thins and loses elasticity with age
• Increased vulnerability to sun exposure leading to skin cancer
• Aging can result in balding and graying hair