01 / Location & anatomical relationships
On your scalp and on much of your skin.
02 / Structure & organization
Each follicle contains a root surrounded by epithelial tissue. Dividing matrix cells near the bulb produce the keratinized shaft. A dermal papilla supports the growing region, while sebaceous glands usually open into the follicle.
03 / Function
Hair on your head helps protect your scalp.
04 / Mechanism
Living cells at the bottom of each follicle build a hair. As new cells form, older cells move upward and become the hair shaft. The hair you see outside the skin is made of hardened, nonliving cells.
Working together: integumentary system
Skin forms a barrier, nerves in the skin notice touch, and sweat helps cool you when it evaporates.
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Connect structure with function
Hair follicles alternate between growth, regression and resting phases. Different follicles cycle independently, and cycle duration differs by body region; this helps explain differences in hair length.
Check your understanding
Locate the hair in relation to its neighbors. Explain how the structural features described above support its function, then distinguish it from a nearby structure with a different role.
Keep learning
Continue with OpenStax Anatomy and Physiology for system-level study. This atlas is educational and has not undergone independent medical peer review.