Anatomy, Physiology and Skin Science
What this domain tests
Anatomy, physiology and skin science underpins every treatment decision. The exam checks correct terminology, the structure and functions of skin, hair and nails, and your ability to link physiology to client safety and treatment outcomes.
Core rules and concepts
- The epidermis is avascular and renews through keratinocyte migration from the stratum basale; melanocytes in the basal layer produce melanin.
- The dermis contains collagen, elastin, glycosaminoglycans, fibroblasts, blood vessels, lymphatics and nerve endings; it is vascular.
- The hypodermis is adipose and connective tissue, providing insulation and support.
- Skin functions: protection, sensation, thermoregulation, excretion, secretion, vitamin D synthesis and limited absorption.
- The acid mantle (approximately pH 4.5–5.5) supports barrier function and resident flora.
- Hair growth cycles: anagen (growth), catagen (transition), telogen (rest); waxing is most effective in anagen.
- Fitzpatrick phototype predicts UV response, not skin sensitivity or treatment tolerance.
Worked example
A client reports stinging after a foaming cleanser. Reasoning: high-pH surfactants can disrupt the acid mantle and intercellular lipids, increasing transepidermal water loss and nerve sensitivity. The plan is to stop the cleanser, use a pH-balanced, fragrance-free cleanser, support barrier repair with emollients, and advise SPF. This links structure (stratum corneum) to function (barrier) and a safe recommendation.
Traps that cost marks
- Saying the dermis is avascular.
- Confusing melanocytes with keratinocytes.
- Claiming skin absorbs most ingredients freely.
- Treating Fitzpatrick type as a measure of sensitivity.
- Describing all hair as growing continuously.