Your Body's Real Age | NPR's SKUNK BEAR

Summary

In this fascinating exploration, Adam Cole answers Lulu Miller's question about how old our bodies really are. He explains how different parts of our body, like hair, skin, and blood cells, are constantly renewed and replaced over time. While some elements, such as the heart and brain neurons, are slower to change, certain aspects, like the lens in your eyes, remain unchanged throughout your life. This video delves into the science behind cellular regeneration and the surprising persistence of parts of your body from birth to death.

Takeaways

• 😀 Your body is constantly regenerating itself, with various parts of it being replaced over time.
• 😀 Your hair is replaced every 2 to 7 years, with around 100 hairs falling out daily and growing back.
• 😀 Fingernails are completely replaced every 6 months or so.
• 😀 The lining of your stomach and intestines is replaced every few days due to constant exposure to acid and bile.
• 😀 Your outer layer of skin is renewed every few weeks.
• 😀 Red blood cells are completely refreshed every 4 months, with 100 million new cells born every minute.
• 😀 The breakdown of red blood cells contributes to bruises and yellow urine.
• 😀 Your skeleton is entirely replaced every 10 years through the process of breaking down and rebuilding bones.
• 😀 Your muscles are renewed every 15 years, although fat cells just grow bigger or smaller, not replaced.
• 😀 Half of your heart cells stay with you for your entire life because they are replaced very slowly.
• 😀 Most of your brain's neurons are developed before birth, but the connections between them—storing memories—continue to change throughout your life.

Q & A

How often does our hair regenerate?

Your hair regenerates every 2 to 7 years, with a hundred hairs falling out each day and new ones growing back in their place.

How frequently do our fingernails renew?

Fingernails are completely renewed every six months or so.

What happens to the cells in the lining of our stomach and intestines?

The cells in the lining of your stomach and intestines are replaced every few days due to constant exposure to acid and bile.

How often does the outer layer of our skin refresh?

Your outer layer of skin is completely renewed every few weeks.

How quickly are red blood cells replaced?

Red blood cells are completely refreshed every four months.

What causes bruises and urine to turn yellow?

The breakdown products of red blood cells, which are constantly being born and destroyed, cause bruises and urine to turn yellow.

How long does it take for our skeleton to completely regenerate?

Your skeleton is completely renewed every 10 years, with a team of cells breaking down old bone and building new bone.

Do our muscles regenerate, and if so, how often?

Your muscles are refreshed every 15 years, although they may grow and shrink in size in the meantime.

Do fat cells regenerate as well?

Fat cells don't completely regenerate when you gain or lose weight; they just become bigger or smaller. However, most fat cells do turn over every 25 years.

What part of your body stays with you your entire life?

There are a few parts of your body that stay with you for life, such as about half of your heart cells, which are replaced very slowly, and your brain's neurons, though their connections constantly change.