Skin test 1

  • Development of the Skin

  • Epidermis develops from the ectodermal germ layer and all layers are present by 16 weeks’ gest.

  • Dermis develops from the mesodermal germ layer by 11 weeks’ gestation

    • At 8 weeks’ gestation, the fetal “skin” is simple cuboidal epithelium

    • Nails begin to form at 10 weeks’ gestation, but don’t reach fingertips until almost term.

    • Oil & sweat glands form in the 4th and 5th month of gestation

    • Lanugo (fetal hair) is formed by the 6th month of gestation

    • At birth, there is a slippery coating of oil and sloughed off skin (vernix caseosa).  














  • Skin Homeostatic Imbalances

  • Infections

  • Athlete’s foot (tinea pedis)

  • Caused by fungal infection

  • Boils and carbuncles

  • Caused by bacterial infection

  • Cold sores

  • Caused by virus

  • Infections and allergies

  • Contact dermatitis

  • Caused by skin being exposed to various chemicals or substances

  • Exposures may cause allergic reaction like an itchy rash

  • Impetigo (staphylococcus)

  • Caused by bacterial infection

  • Psoriasis

  • Cause is unknown

  • Triggered by trauma, infection, stress

  • Skin Color as Diagnostic Clue

  • Jaundice

  • yellowish color to skin and whites of eyes

  • build up of yellow bilirubin in blood from liver disease

  • Cyanotic

  • bluish color to nail beds and skin

  • hemoglobin depleted of oxygen looks purple-blue

  • Erythema 

  • redness of skin due to enlargement of capillaries in dermis

  • during inflammation, infection, allergy or burns

    Burns

  • Tissue damage (destruction of proteins of the skin) and cell death 

  • Caused by:  heat, electricity, UV radiation, or chemicals

  • Associated dangers

  • Dehydration (usually first threat in 3rd degree burns)

  • Electrolyte imbalance

  • Circulatory shock: due to water, plasma and plasma protein loss

  • Circulatory and kidney problems from loss of plasma

  • Bacterial infection



  • Rule of Nines

  • Used to estimate the amount of fluid lost. To save the patient, the fluids must be replaced immediately.

  • Way to determine the extent of burns    

  • Body is divided into 11 areas for quick estimation

  • Each area represents about 9 % of total body surface area



  • Severity of Burns

    \

  • First-degree burns

  • Only epidermis damaged

  • Skin is red and swollen (sunburn)



  • Second-degree burns

  • Epidermis and upper dermis are damaged

  • Skin is red with blisters

  • epidermal derivatives are not damaged

  • heals without grafting in 3 to 4 weeks         

and may scar



  • Third-degree burns  

  • Destroys entire skin layer:

 epidermis, dermis & epidermal derivatives 

  • damaged area is numb due to loss of sensory nerves

  • Burn is gray-white or black



  • Critical Burns

  • Burns are considered critical if…

  • Over 25 % of body has second-degree burns

  • Over 10 % of the body has third-degree burns

  • There are third-degree burns of the face, hands, or feet



  • Skin Grafts

    • New skin cannot regenerate if the stratum basale and its stem cells are destroyed.

    • Skin graft is covering the wound with a piece of healthy skin:

      • Autograft  🡪 from self 

      • Isograft 🡪 from twin

      • Autologous skin 🡪 transplantation of patients skin grown in a culture




  • Age Related Structural Changes

    • Collagen fibers decrease in number and stiffen

    • Elastic fibers become less elastic

    • Fibroblasts decrease in numbers

    • Langerhans cells and macrophages decrease in numbers and become less-efficient phagocytes.

    • Oil glands shrink and the skin becomes more dry

    • Walls of blood vessel in the dermis thicken, therefore decreasing the amount of nutrients available and leads to thinner skin as subcutaneous fats is lost.





  • Photo damage

  • Ultraviolet light (UVA and UVB) both damage the skin

  • Acute overexposure causes sunburn 

  • DNA damage in epidermal cells can lead to skin cancer

  • UVA produces oxygen free radicals that damage collagen and elastic fibers and lead to wrinkling of the skin




  • Skin Cancer

  • Cancer — abnormal cell mass

  • Classified two ways

  • Benign

  • Does not spread (encapsulated)

  • Malignant

  • Metastasized (moves) to other parts of the body

  • Skin cancer is the most common type of cancer, 1 million cases diagnosed per year.





  • 3 Skin Cancer Types

  • Basal cell carcinoma 

    04_12Figure-L.jpg 004E43B8EHAP_for_kym C37AF81A:

  • Least malignant  (rarely metastasize)

  • Most common type

  • Arises from stratum basale



  • Squamous cell carcinoma

  • May metastasize

  • Metastasizes to lymph nodes if not removed

    04_12Figure-L.jpg 004E43B8EHAP_for_kym C37AF81A:

  • Early removal allows a good chance of cure

  • Believed to be sun-induced

  • Arises from stratum spinosum   



  • Malignant melanoma

  • Most deadly of skin cancers, (metastasize rapidly)

  • Most common cancer in young women

  • Cancer of melanocytes – life threatening

  • Metastasizes rapidly to lymph and blood vessels

    04_12Figure-L.jpg 004E43B8EHAP_for_kym C37AF81A:

  • Key to treatment is early detection watch for changes in symmetry, border, color and size

  • Variation noted in pigmentation (coloration).

  • Risks factors include-- skin color, sun exposure, family history, age and immunological status

  • Detection uses ABCD rule