Skin

Anatomy

• Epidermis

  • Barrier against invaders, foreign items, chemicals, and UV rays

  • Stratum corneum - stratum granulosum - stratum spinosum - stratum basale

    • Melanocytes - block solar radiation

    • Langerhans cells - recognize foreign substances and present to lymphocytes

• Dermis

  • Connective tissue

  • Mechanical support to the epidermis

  • Houses blood vessels, nerves, sweat glands, hair follicles, sebaceous glands

  • Adnexal structures

    • Hair, sebaceous glands (secrete sebum), eccrine glands

  • Sweat glands

    • Responsible for cooling surface and internal organs

  • Nails

  • Sensory nerve endings

    • Sensation and recognize temperatures changes in pain

• Subcutis - subcutaneous fat

  • Skin lesions

    • Cafe au lait spots - increase melanin

    • Cellulitis - infectious inflammation

    • Primary lesions

      • Macules

      • Papules

      • Plaques

      • Nodules

      • Tumors

      • Cysts

      • Wheals

      • Vesicles

      • Bullae

      • Pustules

    • Secondary lesions

      • Excoriations

Skin Trauma and Injuries

• Friction/pressure

  • Hyperkeratosis - epidermal skin layer thickens from constant pressure

  • Blisters - raised skin filled with fluid due to friction

  • Soft corns and hard corns

  • Hyperhidrosis - excessive perspiration

  • Changing

  • Xerotic skin - dry skin

  • Ingrown toenails

• Wounds

  • Abrasions - the top layer of skin

  • Punctures - tetanus bacillus

  • Lacerations - sharp object that disrupts tissues

  • Incisions - smooth cut

  • Avulsions - skin is torn away from the body

  • Bruises - ecchymosis

• Allergic reactions

  • Contact dermatitis - allergy to irritant

  • Miliaria - prickly heat

  • Chilblains - Perino - from cold

• Burns

  • Sunburn

• Psoriasis

  • Chronic itching

• Pityriasis rosea

  • Skin rash with no origin

Infections

• Bacterial

  • Staphylococcus - gram-positive bacteria, seen in clumps

  • Streptococcus - gram-positive bacteria, seen in long chains

  • Impetigo - from streptococci

  • Furunculosis - boils

  • Carbuncles - early stages of furunculosis

  • Folliculitis - inflammation of hair follicle

  • Hidradenitis suppurative - inflammation of apocrine glands

  • Acne vulgaris - inflammation of hair follicles and sebaceous glands

  • Paronychia and onychia - infection of proximal/lateral nail folds

  • Tetanus infections

• Fungal

  • Ringworm

    • Tinea capitis - scalp

    • Tinea corporis - body

    • Tinea unguium/onychomycosis - nail

    • Tinea cruris - "jock itch"

    • Tinea pedis - athlete's foot

    • Tinea versicolor - yeast

    • Herpes simplex labialis, gladiatorum, herpes zoster

      • Type 1 - extragenital

      • Type 2 - genital

      • Gladiatorum - face, neck, shoulders - wrestlers

  • Verruca virus and warts

    • Common wart - verruca vulgaris and plana - hands of children

    • Plantar warts - soles of feet; can spread

    • Molluscum contagiosum - pox virus; very contagious

• Infestations and bites

  • Scabies - mites (Sarcoptes scabiei)

  • Lice - pediculosis

    • Pediculus humanus capitis - head lice

    • Phthirus pubis - pubic lice

    • Pediculus humanus corporis - body lice

  • Fleas

  • Ticks - parasitic insect --> Rocky Mountain spotted fever and Lyme disease

  • Mosquitoes

  • Stinging insects - bees, wasps, hornets, yellow jackets

  • Spider bite

    • Black widow and brown recluse cause most problems