Anatomy and Physiology of the Skin
What the exam tests
Anatomy and physiology questions ask you to connect skin structure to treatment choice: why the stratum corneum limits penetration, why the dermis determines scarring, and why glands and blood supply affect reactions.
Core rules
- Epidermis: avascular; keratinocytes move from stratum basale to stratum corneum; melanocytes produce melanin; Langerhans cells are immune; Merkel cells are sensory.
- Dermis: papillary and reticular layers; fibroblasts make collagen and elastin; blood vessels, nerves, glands, and hair follicles sit here.
- The dermal-epidermal junction anchors the epidermis and affects blistering and pigment transfer.
- Hypodermis: fat and connective tissue; insulation and support.
- Appendages: sebaceous glands secrete sebum; eccrine sweat glands cool the body; apocrine glands are in axillae and groin.
- Barrier: acid mantle around pH 4.5–5.5; lipids between corneocytes limit water loss and block irritants.
- Functions: protection, sensation, thermoregulation, excretion, vitamin D synthesis.
- Wound healing: inflammation, proliferation, remodeling; keloids are excess collagen.
Worked example
A client says a serum “burned” after a strong exfoliation. Reasoning: the stratum corneum and acid mantle were compromised, so penetration increased and barrier function dropped. The correct response is to stop actives, soothe, and protect-not to add another acid.
Traps
Confusing melanocytes with keratinocytes; saying the epidermis has blood vessels; placing sebaceous glands on palms and soles; and treating the acid mantle as a fixed wall rather than a dynamic barrier.