Skin Anatomy
Skin Anatomy & Physiology
The layers of the skin, its functions, and the structures within it.
The Layers of Skin
Skin has three main layers: • EPIDERMIS — the outermost layer; no blood vessels. Its deepest layer (stratum germinativum/basale) produces new cells and melanin; the outermost is the stratum corneum (dead, protective cells). • DERMIS — beneath the epidermis; contains blood vessels, nerves, hair follicles, and glands. The 'live' layer. • SUBCUTANEOUS (hypodermis) — fatty layer providing insulation and contour.
The skin is the body's largest organ.
Functions of the Skin
Remember the functions with 'SHAPES': Sensation, Heat regulation, Absorption, Protection, Excretion, Secretion.
The skin protects against pathogens and injury, regulates temperature (sweating, blood flow), senses touch/pain/temperature, and secretes sebum (oil) to lubricate and protect.
Glands & Appendages
• SEBACEOUS (oil) glands — produce sebum; connected to hair follicles. Overactivity contributes to oily skin and acne. • SUDORIFEROUS (sweat) glands — regulate temperature and excrete waste.
The ACID MANTLE is the slightly acidic film (pH ~4.5-5.5) of sebum and sweat that protects skin from bacteria. Estheticians work to support, not strip, this barrier.
📖 Key Terms
- Epidermis
- The outermost skin layer with no blood vessels.
- Dermis
- The layer beneath the epidermis containing vessels, nerves, and glands.
- Sebaceous gland
- Oil gland that secretes sebum; linked to acne when overactive.
- Acid mantle
- The slightly acidic protective film on the skin (pH ~4.5-5.5).
💡 Exam Tips
- ▸The epidermis has no blood vessels; the dermis is the 'live' layer.
- ▸Skin functions = SHAPES: Sensation, Heat regulation, Absorption, Protection, Excretion, Secretion.
- ▸Sebaceous glands produce oil (sebum); sudoriferous glands produce sweat.
- ▸The acid mantle protects skin at pH ~4.5-5.5.