Integumentary system

• Body membranes


  Cover surfaces, line body cavities and form protective (and often lubricating) sheets around organs
• Classification of Body Membranes

  • Epithelial membranes
  • Connective tissue membranes
• Epithelial membranes


  • Cutaneous (skin) – dry membranes that are exposed to air
  • Mucous (mucosa) – lines body cavities that open to the exterior
  • Serous – lines body cavities that are closed to the exterior except for the dorsal and joint cavities
• Serous fluid


  Allows organs to slide easily across the cavity walls and one another without friction as they carry out their functions
• Connective tissue membranes


  • Synovial membranes – composed of connective tissue, line the fibrous capsules surrounding joints, also secrete a lubricating fluid
  • Bursae – sacs of connective tissue
  • Tendon sheaths – tube-like structures
• Skin


  The largest organ and is called the cutaneous membrane
• Functions of the Skin

  • Protection
  • Insulation
  • Cushion
  • Excretion
  • Sensation
  • Production of Vitamin D
• Layers of the Skin

  • Epidermis
  • Dermis
  • Hypodermis or Subcutaneous tissue
• Epidermis


  • Avascular (has no blood supply of its own)
  • Contains keratinocytes – keratin cells that make up most of the epidermis
  • Contains Granstein cells that help with immune response
  • Has 5 layers called strata
• Layers of the Epidermis

  • Stratum basale
  • Stratum spinosum
  • Stratum granulosum
  • Stratum lucidum
  • Stratum corneum
• Dermis


  • Contains sensory receptors, blood vessels, and glands
  • Papillary Layer – upper dermal region with fingerlike projections
  • Reticular Layer – deepest skin layer containing blood vessels, sweat/oil glands, and deep pressure receptors
• Hypodermis or Subcutaneous tissue

  Contains adipose tissue (fat), anchors skin to underlying organs, serves as shock absorber and insulation for deeper tissues
• Factors determining skin color

  • Amount and kind of pigment
  • Amount of carotene deposited
  • Amount of oxygen bound to hemoglobin
• Skin Color Alterations


  • Cyanosis
  • Erythema
  • Blanching
  • Jaundice
  • Bruises
• Appendages of the skin

  • Cutaneous glands (sweat glands)
  • Hair
  • Nails
• Cutaneous Glands


  • Sebaceous – produce sebum to lubricate and keep skin soft
  • Sudoriferous – sweat glands (eccrine and aprocrine)
• Hair


  • Protective functions
  • Produced by a hair follicle
  • Shaft – the part projecting from the surface of the scalp or skin
  • Humans are born with as many hair follicles as they will ever have
  • Hormones account for the development of "hairy" regions
  • Goose bumps are the flexing action of the arrector pili muscle attached to the hair follicle

  
• Nails


  • A scale-like modification of the epidermis
  • Nail matrix is responsible for nail growth
  • Transparent and colorless, but look pink due to the rich blood supply in the underlying dermis
  • Lunula appears whitish due to the thickened stratum basale

  
• Common skin disorders


  • Allergies (contact dermatitis)
  • Infections (bacterial, viral, fungal)
  • Acne
  • Skin parasites (hair mites, bed bugs)
  • Psoriasis
  • Systemic lupus erythematosus
• Burns


  • Tissue damage and cell death caused by intense heat, electricity, UV radiation, or certain chemicals
  • Body loses fluid supply, leading to dehydration, electrolyte imbalance, and circulatory shock
• The body divided into 11 areas, each accounting for 9% of the total body surface area - the Rule of Nines
• Systemic lupus erythematosus


  An autoimmune disease in which the body's immune system attacks healthy tissues; cause is unknown but believed to involve hormonal, environmental and genetic factors; symptoms include a "butterfly rash" across the nose and cheeks, inflammation, swollen lymph nodes, tiredness, fever, chest pain, hair loss, mouth ulcers. Can cause damage to blood vessels throughout the body
• Burn


  Tissue damage and cell death caused by intense heat, electricity, UV radiation (sunburn), or certain chemicals (such as acids)

  
• Problems resulting from skin being burned

  1. Body loses its supply of fluids

  2. Infection becomes the most important threat and is the leading cause of death in burn victims

  
• Partial-thickness burns


  • First-degree burns - only epidermis is damaged; area is red and swollen
  • Second-degree burns - injury to the epidermis and upper region of the dermis; skin in red and painful and blisters appear

  
• Full-thickness burns


  Third-degree burns - entire thickness of the skin is destroyed; area appears blanched or blackened; nerve endings are destroyed and burned area is not painful

  
• Critical burns


  • Over 25% of the body has 2nd degree burns
  • Over 10% of the body has 3rd degree burns
  • There are 3rd degree burns of the face, hands, or feet

  
• Skin cancer


  Numerous types of tumors arise in the skin; most are benign and do not metastasize; some are malignant and tend to invade other body areas; skin cancer is the single most common type of cancer in humans

  
• Risk factors for melanoma

  • Fair skin, blond/red hair, light-colored eyes
  • Family history of melanoma
  • Sun exposure/overexposure to UV radiation
  • Early childhood sunburns
  • Many freckles
  • Many ordinary moles
  • Dysplastic nevi (Atypical mole)
  • Infections
  • Chemicals
  • Physical Trauma
• Basal cell carcinoma


  Least malignant, most common; starts in the basal cell layer of the epidermis and grows very slowly; usually appears as a small, shiny bump or nodule on the skin - mainly those areas exposed to the sun

  
• Squamous cell carcinoma


  Grows rapidly and metastasizes to adjacent lymph nodes if not removed; may appear as nodules or red, scaly patches of skin, and may be found on the face, ears, lips, and mouth; arises from the cells of the stratum spinosum; believed to be sun-induced

  
• Malignant melanoma


  Cancer of the melanocytes; often deadly; can begin wherever there is pigment; usually appears as a spreading brown to black patch that metastasizes rapidly; chance for survival is about 50%; early detection is a must

  
• ABCD rule for melanoma

  Asymmetry, Border Irregularity, Color, Diameter

  
• Skin changes with aging

  Skin becomes thinner, fat disappears from the subcutaneous tissue, wrinkles appear; sunlight can speed up the loss of elasticity
• Balding and graying


  Genetically controlled by a "delayed-action" gene; by age 50 the number of hair follicles drops by 1/3 and may continue to decline; the amount of melanin deposited in the hair decreases or becomes totally absent, resulting in gray-to-white hair
• Factors influencing balding/graying


  • Drugs/medication
  • Hair treatments (chemical alterations, overstyling)
  • Emotional stress/anxiety
  • Hormonal changes
  • Diseases/sickness
  • Insufficient diet/poor nutrition
• When to see a doctor about balding

  Talk to your doctor if you notice sudden or patchy hair loss or more than usual hair loss when combing or washing your hair. Sudden hair loss can signal an underlying medical condition and may require medical treatment.
• Types of permanent hair loss

  • Male-pattern baldness (androgenetic alopecia)
  • Female-pattern baldness (androgenetic alopecia)
  • Cicatricial (scarring) alopecia
• Types of hair loss

  • male pattern baldness
  • female pattern baldness
  • traction alopecia
  • alopecia areata
• Synovial membranes


  Connective tissue membranes that line the fibrous capsules surrounding joints and secrete a lubricating fluid called synovial fluid.