Hair shaft (magnified skin block)

Scapus pili

Integumentary (skin)SkinLeg

View in 3D

What it is

The dead, keratinised hair emerging from the follicle, made of a medulla, a pigmented cortex and a scaly cuticle.

Function

Insulation, protection and touch sensing (bending the hair stimulates nerve endings around the follicle).

Size

Scalp hair ~50–100 µm diameter (magnified here)

Clinical note

Hair records exposure to drugs and toxins as it grows, so a segment of hair can date exposure month by month.