Hair & Nails

Hair and nails are made of hard keratin.

We have millions of hairs on most parts of our body.

Functions of hair:

• Head hair: keeps in heat and protects from the sun.

• Body hair: alerts to insects.

• Eyelashes: protects the eyes.

• Nose hair: prevents the entry of foreign objects.

The part of the hair that sticks out of the skin is called the shaft. It is protected by the outermost layer called a cuticle. The hair follicle (root) is located within the dermis. Hair cells divide within the follicle in a region called the hair bulb. The cells are filled with keratin and pigments. These dead cells are continually pushed out as new cells are formed. Tiny arrector pili muscles attach to the hair shaft to make hair “stand on end.”

Nails are protective and useful as tools.

Nails have 4 basic parts:

• Free edge (visible)

• Body (visible)

• Root (not visible)

• Nail bed (not visible)

The nail matrix produces heavily keratinized cells, which become the nail body.

The nail is protected on 3 sides by nail folds.

The lunula (“little moon”) is whiter due to the thickness of the nail.

Summary: Hair and nails provide protection due to their high keratin content. Hair grows from the hair bulb, while nails grow from the nail matrix.