Written by the Fiveable Content Team • Last updated August 2025
Written by the Fiveable Content Team • Last updated August 2025
Definition
Keratin is a fibrous structural protein found in the outer layer of the skin, as well as in hair and nails. It provides protection and strength to epithelial cells against damage or stress.
AP course connection
Topic 21.1: 21.1 Anatomy and Normal Microbiota of the Skin and Eyes