Skin Care and Esthetics Fundamentals
Domain 1 - Skin Care and Esthetics Fundamentals - tests how well you connect skin anatomy, barrier function, skin type versus skin condition, and ingredient precautions to safe service decisions.
Structure and barrier
The epidermis is avascular and renews from the basal layer; melanocytes there produce melanin. The dermis holds collagen, elastin, nerves, and blood vessels; the subcutaneous layer stores fat. The stratum corneum and acid mantle (about pH 4.5–5.5) limit water loss and irritant entry. Barrier damage shows as tightness, stinging, flaking, or sensitivity.
Type versus condition
Skin type is genetically based: normal, dry, oily, combination. Conditions are temporary or medical: acne, rosacea, hyperpigmentation, dehydration. Fitzpatrick I–VI estimates UV response and guides treatment intensity.
Ingredients
AHAs are water-soluble and exfoliate the surface; BHA is oil-soluble and useful for oily, comedone-prone skin. Retinoids increase turnover and photosensitivity; pregnancy and irritation risk matter. Vitamin C is an antioxidant; niacinamide supports barrier and redness; broad-spectrum sunscreen is non-negotiable after exfoliation.
Worked example: A client with oily skin and rosacea asks for a “strong scrub.” Rosacea is a condition, not a skin type. Choose a gentle cleanser, avoid heat and abrasive scrubs, use niacinamide and sunscreen, and do not extract inflamed papules; refer persistent redness to a physician.
Traps: calling rosacea a skin type; over-exfoliating; skipping a patch test; assuming “natural” means non-irritating; omitting sunscreen after AHAs or retinoids.