Integumentary System - Key Terms and Concepts (Vocabulary Flashcards)

Integumentary System Basics

  • Skin layers: epidermis, dermis, hypodermis
  • Keratin barrier; UV protection; water-repellence
  • Trauma can separate dermis from epidermis; bleeding; nerves, vessels, lymphatics involved
  • Sweat glands, hair, nails; microbiota niches; folliculitis risk
  • Normal skin microbiota influenced by environment, diet, hygiene; common genera: Staphylococcus, Streptococcus, Propionibacterium acnes

Normal Skin Microbiota and Defenses

  • Microbiota vary with environment, trauma, hygiene; can be altered by pH and lipids
  • Defenses: lysosome enzymes in sweat, tears, saliva; IgA
  • Key organisms discussed: Staphylococcus aureus, Streptococcus pyogenes; Propionibacterium acnes present as normal flora

Staphylococcus aureus and MRSA

  • Gram-positive cocci in grape-like clusters; nonmotile; non-spore-forming
  • MRSA vs MSSA: methicillin-resistant vs methicillin-sensitive
  • Enzymes/toxins: coagulase; hyaluronidase; catalase
  • Catalase test differentiates Staph (positive) from Strep (negative)
  • Exfoliative toxins A and B (relevant to SSSS)
  • MRSA treatment: vancomycin
  • Common lesions: skin infections; hospital- and community-acquired
  • Transmission: direct contact; skin breaks; catheter-related

Impetigo

  • Superficial infection; honey-gold crust; may be S. aureus, S. pyogenes, or both
  • Treatment: topical antibiotics

Cellulitis

  • Deep skin infection; pain, swelling, warmth; fever possible
  • Rapid spread; red line indicates spread; thigh common
  • Risk: immunocompromise, diabetes, heart disease

Staphylococcal Scalded Skin Syndrome (SSSS)

  • Exfoliative toxins A and B
  • Epidermal separation at the granular layer; superficial but serious
  • Mostly in young children; higher mortality in adults

Gas Gangrene (Clostridium perfringens)

  • Anaerobic, spore-forming; endospores in soil
  • Alpha toxin; gas production; myonecrosis and tissue destruction
  • Imaging: gas bubbles; treatment: debridement, antibiotics, oxygen therapy
  • Mortality ~25% if untreated; worse with delays

Skin Lesion Nomenclature

  • Bulla: large blister; Cyst: small, semisolid
  • Macule: flat color change; Maculopapular: flat with raised component
  • Papule: small raised bump; Vesicle: fluid-filled; Pustule: pus-filled
  • Plaque: large, raised; Petechiae: tiny red dots; Purpura: non-blanching bruising; Scales: flaky skin

Leishmaniasis and Anthrax

  • Leishmaniasis: Leishmania donovani; vector: sandfly; cutaneous vs mucocutaneous; treated with antiparasitics
  • Cutaneous anthrax: Bacillus anthracis; black eschar; direct contact; treatment with antibiotics; debridement

Loa loa and Other Parasites

  • Loa loa: filarial parasite; vector: deer fly; Calabar swelling; ocular involvement

Fungal Infections

  • Dermatophytes cause tinea infections: capitis, barbae, corporis, cruris, pedis; onychomycosis
  • Tinea versicolor (pityriasis versicolor): Malassezia furfur; pigment changes; treat with azoles
  • Transmission via direct contact, shared items, barber tools; proper hygiene

Warts, Molluscum Contagiosum

  • Warts: HPV; plantar, common, flat; genital warts types 6 & 11; cervical cancer risk with high-risk types (16, 18)
  • Vaccination recommended in preadolescence; reduces risk
  • Molluscum contagiosum: poxvirus; small umbilicated papules; removal if symptomatic

Viral Exanthems

  • Measles (rubeola): droplet; fever, cough, conjunctivitis; Koplik spots; trunk-to-extremities rash; MMR vaccine; risk of subacute sclerosing panencephalitis (rare)
  • Rubella (German measles): milder rash; congenital rubella causes fetal defects; vaccination; pink maculopapular rash
  • Fifth disease (erythema infectiosum): Parvovirus B19; slapped-cheek cheeks; fever; mild
  • Roseola (HHV-6): high fever for several days; rash after fever; common in infants; high adult exposure; febrile seizures risk

Varicella and Herpes Zoster

  • Varicella (chickenpox): Varicella-zoster virus (VZV); vesicular rash all over body; incubation 10–20 days; lasts 4–7 days; Varicella vaccine available
  • Shingles (herpes zoster): reactivation of VZV; unilateral dermatomal distribution; neuralgia risk; vaccine around age 50
  • Note: Shingles requires prior varicella infection

Transmission and Prevention Notes

  • Modes: droplets, direct contact, vectors, autoinoculation
  • Vaccines: MMR, Varicella, HPV
  • Hygiene and wound care are essential for prevention