4.1. Skin Structure and Function

💡 First Principle: The skin is the body's largest organ, and it performs multiple critical functions. Understanding its structure — especially its layers — explains why different treatments target different depths, and why certain conditions affect the skin in predictable ways.

The exam primarily tests the layers of the skin, their functions, and the appendages (glands, follicles) embedded within them. Know the names, locations, and functions of each layer.

⚠️ Common Misconception: Students often focus only on the outermost layer (stratum corneum) because it's what they see and work on. But the exam tests all five layers of the epidermis plus the dermis and subcutaneous layer — and asks about the functions of each.