We lose hair every day, but we don't usually go bald; we cut our nails, but they still grow back. We remove dead skin cells to give it smoothness and radiance, we carry out procedures that start the process of skin regeneration.
All this is possible thanks to the body's ability to renew itself. You must have heard that the human body is completely renewed every 7 years, that is, at the end of this period you become a different person, because every cell of your body is replaced by a new one.
Sounds amazing! But is this really so and why do we, despite the renewal of the body, continue to age? Estet-portal.com decided to look into this issue.
Renewal of the body: each cell has its own "service life"
Indeed, the lifetime of individual cells of the human body is limited. After the expiration of this period, the cells die, and new ones take their place. The body of an adult consists of a huge number of cells – approximately 50 & ndash; 75 trillion & ndash; and each type of cell has its own "lifetime".
After the death of a person, not all cells die immediately – some of them take a few minutes, others – hours, the third – day. Cell death rate – one of the factors that is used to determine the cause and time of a person's death.
Cell death rate – one of the factors that is used to determine the cause and time of a person's death.
Below estet-portal.com will review:
- approximate time of renewal of various cells, tissues and organs of the body;
- why we get old.
How fast is the renewal of body cells
The following are approximate rates of cell renewal in the human body:
1. Red blood cells (erythrocytes), which carry oxygen, live for about four months.
2. The average lifespan of white blood cells is just over a year. At the same time, the most numerous group of leukocytes – neutrophils – live only a couple of hours, eosinophils – 2–5 days.
3. Platelets live for about 10 days.
4. Lymphocytes are renewed at a rate of 10 000 cells per second.
5. Epidermal cells are renewed approximately every 10-30 days of the week, the skin recovers 4 times faster after minor injuries.
6. "Age" hair on the head can reach 6 – 7 years. Every day, the hair on the head grows by about 0.5 mm. Hair on other parts of the body – about 0.27 mm per day. Eyebrows are renewed every 64 days.
7. The surface of the cornea of the eye is covered with a thin layer of cells that are constantly updated in 7-10 days. Retinal cells are not updated, as is the lens of the eye, therefore, age-related deterioration of vision – common problem. However, experts are developing methods of retinal regeneration using stem cells.
8. The epithelial cells of the small intestine are renewed every 2-4 days, the colon – approximately every 4 days, the gastric mucosa – about 5 days.
9. Cells in the cerebral cortex, as far as we know today, are not capable of regeneration, unlike hippocampal neurons. Damaged nerve cells can recover to a certain extent if the body of the neuron is not damaged.
10. The rate of nerve regeneration after injury is approximately 2-3 mm per day.
11. The average age of a fat cell – 8 years. Every year, 10% of fat cells are replaced by new ones.
12. liver cell renewal takes approximately 300-500 days. The human liver has an excellent ability to regenerate. If you remove 70% of this organ, it will recover to normal size in just a couple of months. Surgeons removed even 90% of the liver, but the recovery in this case was incomplete.
13. It takes 300-500 days for kidney and spleen cells to renew themselves.
14. Nails grow about 3.5mm monthly, although the pinky nail grows the slowest. Toenails grow at a rate of about 1.6 mm per month, with the thumbnail growing the fastest.
15. Heart – one of the slowest regenerating organs in the human body. In a 25-year-old person, only 1 percent of heart cells are renewed annually, this figure decreases with age. Less than half of the heart cells are renewed in a lifetime.
Heart – one of the slowest regenerating organs of the human body.
16. The taste buds on the tongue are renewed every 10 days.
17. Fingertips can partially regenerate after injuries. The best results are observed in children a few months after the injury. An unaffected nail bed is needed to restore the fingertips. The new fingertip is sensitive and has a fingerprint.
18. The mucous membrane of the bronchioles is renewed every 2-10 days.
19. Microscopic air sacs – alveoli – are updated in 11 & ndash; 12 months, and the surface cells of the lungs – in 2–3 weeks.
20. Muscle cells – «long-livers», since their life span – 15 years old.
21. Skeleton cells are constantly updated, but rather slowly – 10% per year, and it takes about 10 years to completely replace the skeletal cells.
Why, despite the renewal of the body, we grow old
The fact of body renewal was established in the early 50s during the observation of the movements of objects with radioactive atoms embedded in them. Jonas Friesen, a molecular biologist from Sweden, has been studying body renewal by measuring levels of radioactive carbon-14.
He found that every 7-10 years most of the body's cells are replaced by new ones. Of course, this figure is conditional, taking into account the rate of renewal, for example, of heart and skeletal cells or the lack of the ability to regenerate certain neurons, retinal cells, lens, oocytes.
However, with age, the body's ability to regenerate decreases, and an effective way to prevent aging and death has not yet been found.
Geneticists believe that the cause of aging is hidden in cellular DNA, or rather, in its terminal sections – telomeres. There are several theories of aging, as well as a number of factors that influence this process.
Scientists continue to study the features of body renewal, the causes of aging and methods to prevent this process. Estet-portal.com hopes that one day they will be able to give the world a revolutionary discovery, thanks to which the immortality of man will become a reality.
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