Lesson 4 ·Class 9 · Skin — "The Jack of All Trades" · Match Lab
Hair and Nails
Dead structures made of keratin.
Match each part to what it is.
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Free play — tap an item on the left, then its partner on the right; each link tells you why. Switch to when you're ready to test yourself.
In both hair and nail, everything visible is dead and everything living is hidden — which is exactly why cutting them does not hurt.
What this lesson covers
Challenges to clear
- Match every part.
- Connect goose pimples to the part of the skin that causes them.
The task
Match each part to what it is.
What this lesson covers
- Hair shaft — The visible part above the skin — made of dead keratinised cells (Which is why cutting it is painless.)
- Hair root and follicle — The living part below the surface, from which the hair grows (Only cells at the base of the follicle divide.)
- Erector muscle — Pulls the hair upright, causing goose pimples (It traps a layer of insulating air — very useful in a furred animal, less so in us.)
- Sebaceous gland — Opens into the follicle and oils the hair and skin (Sebum keeps hair supple and skin from cracking.)
- Nail plate — The hard visible nail, of dead keratinised cells (Same material as hair, packed more densely.)
- Nail bed and root — The living tissue under and behind the nail, where growth occurs (Damage here, unlike damage to the plate, is painful and can deform the nail.)
- Lunula — The pale crescent at the base of the nail (It looks white because the tissue beneath it is not yet fully attached.)
Hint
In both hair and nail, everything visible is dead and everything living is hidden — which is exactly why cutting them does not hurt.