Skin (Integumentary System): Clinical Correlations
Skin has three layers: epidermis (outer, protective), dermis (structural, vascular, appendages), and hypodermis (fat insulation). The epidermis continuously renews — basal keratinocytes migrate upward and are shed as dead corneocytes over approximately 28 days.
Normal Function
Clinical Correlations perspective: Barrier protection against pathogens, chemicals, UV radiation, and physical trauma. Temperature regulation, sensation, vitamin D synthesis (requires UV), immune surveillance, fluid retention.
Lunar Adaptations
On Arrival (First Weeks)
Reduced UV exposure (no outdoor solar UV in habitat) means vitamin D synthesis ceases. Skin microbiome changes from habitat environment — different microorganism exposure than Earth. EVA suit wear begins causing pressure and friction effects on protected skin areas.
6-Month Resident
Skin adapts to habitat humidity and temperature. Some residents develop skin dryness from low-humidity habitat air. Radiation effects begin accumulating in skin DNA — not yet clinically apparent. Melanin production decreases slightly from reduced UV stimulation.
Long-Term Resident (2+ Years)
Significant cumulative radiation UV equivalent dose to skin during EVA operations. Sun-shielded skin (majority of body in suit) is protected, but any exposed areas (face during habitat time) accumulate changes. Accelerated photoaging pattern distinct from Earth (cosmic radiation rather than UV). Vitamin D synthesis permanently compromised without supplementation.