Anatomy and physiology of the skin and body systems
What this domain tests
This domain checks the structure and function of skin and the body systems that affect treatment safety and client assessment. You need to link anatomy to contraindications, skin responses and aftercare rather than label diagrams alone.
Core rules
- The epidermis is avascular and renews from the stratum basale. Keratinocytes migrate through the stratum spinosum and granulosum to the stratum corneum. Melanocytes produce melanin; Langerhans cells participate in immunity.
- The dermis contains collagen and elastin fibres, fibroblasts, blood vessels, lymphatics, nerves and appendages. The hypodermis stores fat and insulates.
- Skin functions include protection, sensation, thermoregulation, excretion, secretion, vitamin D synthesis and absorption. Barrier damage increases water loss and irritation risk.
- Hair growth cycles: anagen is growth, catagen is transitional and telogen is rest. Waxing is most effective in anagen. Hair colour and density depend on genetics and hormones.
- Sebaceous glands secrete sebum; eccrine sweat glands regulate temperature; apocrine glands are scent-associated.
- Circulatory, lymphatic, nervous, endocrine, immune, respiratory and digestive systems influence skin. Diabetes, thyroid disease, pregnancy, infection and medications can change treatment risk.
Worked example
A client has a raised, hot, red area with fever. The skin sign may reflect infection or inflammation, not simply 'sensitive skin'. Because the barrier is compromised and systemic illness may be present, do not treat; advise urgent medical assessment and record the referral.
Traps
Saying the epidermis contains blood vessels; confusing sebaceous and sweat glands; treating active infection as a cosmetic problem; and forgetting that hormones and drugs alter skin reactivity.