LEVEL 1
Skin Structure & Science
You touch your skin every day, yet you probably know very little about what's inside it. Skin isn't just a single thin membrane -- it's an intricate structure of 3 distinct layers stacked together.
Think of it like a French mille-feuille. Just as pastry layers and cream alternate, your skin's "epidermis," "dermis," and "subcutaneous tissue" stack beautifully, each serving a different purpose.
The outermost epidermis is only about 0.2mm thick -- roughly the thickness of plastic wrap. Yet this thin layer provides the barrier function that protects against external irritants, UV rays, and bacteria.
Epidermal cells are pushed upward from the basal layer to the stratum corneum over approximately 28 days, eventually shedding as dead skin. This is the skin's metabolic cycle known as turnover.
Below the epidermis, the dermis is about 1-3mm thick, making up roughly 90% of total skin thickness. It contains a network of collagen (strength), elastin (elasticity), and hyaluronic acid (moisture), creating the skin's firmness, bounce, and hydration.
When the dermis deteriorates, wrinkles and sagging develop. Most "anti-aging" skincare targets this dermal layer.
The deepest layer, subcutaneous tissue, is primarily composed of fat. It absorbs impact as a cushion, insulates to maintain body temperature, and stores energy.
Areas where skin feels thin or prone to sagging may be related to the thickness of this subcutaneous layer.
By knowing which layer a skincare product targets, you can identify the care you truly need. In the next level, we'll explore the mechanisms of epidermal turnover in detail.
KAIAN develops skincare products based on scientific evidence.
Feel free to ask questions about ingredients and formulations.
