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

One-way valves in leg veins stop blood falling back toward the feet. The figure is taken from NHLBI, 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

Valves and calf muscles push blood uphill

One-way valves in leg veins stop blood falling back toward the feet Veins carry blood at low pressure, so leg veins rely on valves and on the squeeze of surrounding muscle. Contracting calf muscles compresses the veins and pushes blood upward, while valves close behind it. Standing still for long periods leaves this pump idle and blood pooling. It sits in Mondo's human body collection, one of 200 facts that each trace back to the reference below.

Where this comes from

NHLBI

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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More facts like this

The heart feeds itself through coronary arteriesCardiac muscle takes its blood from branches that leave the aorta just above the valve Cold narrows the vessels in fingers and toesReduced skin blood flow keeps warm blood in the core at the cost of cold extremities The body produces millions of red blood cells every secondRed blood cells circulate for about 120 days before being recycled The human heart beats over one hundred thousand times dailyPumping continuously the heart propels thousands of litres of blood every day An average adult body contains about five litres of bloodBlood accounts for roughly seven to eight percent of total adult body weight Capillary walls are only one single cell layer thickThin vascular walls enable rapid diffusion of oxygen and metabolic nutrients

Tags: veins, valves, circulation

Valves and calf muscles push blood uphill: the short answers

Where does this come from, and can I check it?: One-way valves in leg veins stop blood falling back toward the feet. The figure is taken from NHLBI, 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.