Anatomy and Physiology of Skin, Hair and Nails
Anatomy and Physiology tests the structure and function of skin, hair and nails, and how this knowledge guides safe service choices. Expect questions on skin layers, glands, hair growth stages, nail structure and acid mantle.
Skin
- Epidermis: outer protective layer; the stratum corneum is the dead, keratinised surface; the basal layer produces new cells.
- Dermis: contains collagen, elastin, blood vessels, nerves, sweat glands and sebaceous glands.
- Hypodermis: fat and connective tissue; cushions and insulates.
- Acid mantle: slightly acidic film, about pH 4.5–5.5, which helps limit microbial growth.
Hair
- Hair shaft has cuticle, cortex and medulla; the follicle anchors hair in the skin.
- Growth cycle: anagen (active growth), catagen (transition) and telogen (rest and shedding).
- Sebaceous glands release sebum, which conditions hair and scalp.
Nails
- Nail plate is keratinised; the matrix produces the nail; the cuticle seals the nail base; the lunula is the visible part of the matrix; the hyponychium is under the free edge.
Worked example
A client wants cuticle cutting. Reasoning: the cuticle seals the nail base, so cutting live tissue can open a route for infection. The safe service is to soften and gently push back only the non-living cuticle, then moisturise. Damage to the matrix, by contrast, can permanently affect nail shape.
Traps that cost marks
- Saying nails grow from the tip.
- Claiming shaving makes hair thicker.
- Saying pores open and close.
- Confusing the cuticle with the nail plate.
- Treating the acid mantle as alkaline.