Where does this come from, and can I check it?

Pressure prompts extra keratin production, building a tougher surface over time. The figure is taken from NHS, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a human body fact?

Yes. It sits on the Human Body shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

What else can I read about it?

The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

Repeated friction thickens the outer skin layer

Pressure prompts extra keratin production, building a tougher surface over time Mechanical stress on the skin triggers cells in the basal layer to divide faster. The extra cells mature into hardened keratin as they rise, forming a callus. Guitarists, rowers and manual workers develop them where tools or equipment press hardest. It sits in Mondo's human body collection, one of 200 facts that each trace back to the reference below.

Where this comes from

NHS

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Science trivia

More facts like this

Hair and fingernails are composed of the protein keratinTough structural proteins form non-living outer protective structures Each spinal nerve owns a strip of skinDermatomes are skin territories mapped to the single nerve root that serves them Skin loses collagen and elasticity with ageCollagen production in the dermis falls while existing fibres become fragmented Cold narrows the vessels in fingers and toesReduced skin blood flow keeps warm blood in the core at the cost of cold extremities Goosebumps are caused by tiny hair follicle muscles contractingArrector pili muscles pull skin hairs upright in response to cold or emotion Skin is the body largest organ by area and weightCovering roughly two square metres skin shields internal organs from injury

Tags: skin, keratin, callus

Repeated friction thickens the outer skin layer: the short answers

Where does this come from, and can I check it?: Pressure prompts extra keratin production, building a tougher surface over time. The figure is taken from NHS, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a human body fact?: Yes. It sits on the Human Body shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.