A person is completely renewed in 7 years. The structure and properties of human skin: Dermis. Why do we age when we renew ourselves?

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It is known that the cells in our body are renewed. But how does it happen? And if the cells are constantly being renewed, then why does old age come, and not eternal youth last?

The Swedish neurologist Jonas Friesen found that every adult is, on average, fifteen and a half years old! But if many of the “details” of our body are constantly being updated and, as a result, turn out to be much younger than their owner, then some questions arise. For example, why doesn't the skin remain smooth and pink all the time, like a baby's, if the top layer of the skin is always two weeks old? If the muscles are about 15 years old, then why is a 60-year-old woman not as flexible and mobile as a 15-year-old girl?

Friesen saw the answers to these questions in the DNA in the mitochondria (this is part of every cell). She quickly accumulates various damage. That is why the skin ages over time: mutations in mitochondria lead to a deterioration in the quality of such an important component of the skin as collagen.

According to many psychologists, aging occurs due to the mental programs that have been instilled in us since childhood.

Here we consider the timing of the renewal of specific organs and tissues, which are shown in the figures. Although everything is written there in such detail that this commentary may be unnecessary.

Renewal of organ cells

Brain

Brain cells live with a person throughout his life. But if the cells were updated, the information that was embedded in them would go with them - our thoughts, emotions, memories, skills, experience.

Wrong way of life - smoking, drugs, alcohol - all this to one degree or another destroys the brain, killing part of the cells.

And yet, in two areas of the brain, cells are being renewed.

One of them is the olfactory bulb, which is responsible for the perception of smells.

The second is the hippocampus, which controls the ability to assimilate new information in order to then transfer it to the "storage center", as well as the ability to navigate in space.

Heart

The fact that heart cells also have the ability to renew has become known only recently. According to researchers, this only happens once or twice in a lifetime, so it is extremely important to preserve this organ.

Lungs

For each type of lung tissue, cell renewal occurs at a different rate. For example, the air sacs at the ends of the bronchi (alveoli) regenerate every 11-12 months.

But the cells located on the surface of the lungs are updated every 14-21 days. This part of the respiratory organ takes on most of the harmful substances coming from the air we breathe.

Bad habits (primarily smoking), as well as a polluted atmosphere, slow down the renewal of the alveoli, destroy them and, in the worst case, can lead to emphysema.

Liver

The liver is the champion of regeneration among the organs of the human body. Liver cells are renewed approximately every 150 days, that is, the liver is “born again” once every five months. It is able to recover completely, even if, as a result of the operation, a person has lost up to two-thirds of the organ.

It is the only such organ in our body.

Of course, such endurance of the liver is possible with your help to this organ: the liver does not like fatty, spicy, fried, smoked foods. In addition, its work is greatly complicated by alcohol and most drugs.

And if you do not pay attention to this organ, it will cruelly take revenge on its owner with terrible diseases - cirrhosis or cancer. (By the way, if you stop drinking alcohol for eight weeks, the liver is able to completely cleanse).

Intestines

The walls of the intestines are covered with tiny villi from the inside, which ensure the absorption of nutrients. But they are under the constant influence of gastric juice, which dissolves food, so they do not live long. Terms of their renewal - three to five days.

Skeleton

The bones of the skeleton are updated continuously, that is, at every moment in the same bone there are both old and new cells. It takes about ten years to completely renovate the skeleton.

This process slows down with age, as bones become thinner and more fragile.

Renewal of body tissue cells

Hair

Hair grows an average of one centimeter per month, but hair can completely change in a few years, depending on the length. For women, this process takes up to six years, for men - up to three.

Eyebrow and eyelash hairs grow back in six to eight weeks.

Eyes

In such a very important and fragile organ as the eye, only corneal cells can be renewed. Its top layer is replaced every 7-10 days. If the cornea is damaged, the process occurs even faster - it is able to recover in a day.

Language

10,000 receptors are located on the surface of the tongue. They are able to distinguish the tastes of food: sweet, sour, bitter, spicy, salty. The cells of the tongue have a rather short life cycle - ten days.

Smoking and oral infections weaken and inhibit this ability, as well as reduce the sensitivity of taste buds.

Leather

The surface layer of the skin is renewed every two to four weeks. But only if the skin is provided with proper care and it does not receive an excess of ultraviolet radiation.

Smoking also has a negative effect on the skin - this bad habit accelerates skin aging for two to four years.

Nails

The most famous example of organ renewal is nails. They grow back 3-4 mm every month. But this is on the hands, on the legs the nails grow twice as slowly.

The nail on the finger is completely renewed on average in six months, on the toe - in ten.

Moreover, on the little fingers, the nails grow much more slowly than the others, and the reason for this is still a mystery to physicians.

The use of drugs slows down the recovery of cells throughout the body!

Now you have realized what affects the renewal of body cells?

Draw your own conclusions!

SEND:


Follow @chaskor

We all will die

Is old age possible without disease?

Old age is a risk factor for many serious diseases. Cardiovascular and neurological diseases, the risk of developing cancer, heart attack and diabetes are the faithful companions of the elderly. Some scientists hope that one day we will be able to treat all these diseases at once, but the main thing is to deal with the aging process. Who is right?

mother for grandson

What to do if a grandmother tries to raise your child in her own way

Each parent should understand what roles grandmothers play in the family: a nanny, a teacher, an adviser, a rare guest ... Often this understanding comes in the process, because the birth of a child is the appearance of a strong "Agent of Change", which means the whole family system is changing. You, like no one else, know your parents and can imagine what difficulties will await you. If some moments in communication with grandmothers were unexpected for you, you should not make a big tragedy out of this, but you need to figure out the reasons and find a healthy solution.

Active life in old age

What is aging and how to grow old with pleasure

Recently, aging has become a popular topic. Against the backdrop of objective global trends in population aging, increasing life expectancy and the percentage of older people, more and more people are turning to this issue. Olga Yuryevna Strizhitskaya, Candidate of Psychological Sciences, Associate Professor of St. Petersburg State University, talks about what aging is and how you can grow old with pleasure.

Aging is inevitable. Growing up is selective.

Old people usually do not regret what they have done, they mourn what they did not have time to do.

To truly live, you need to dream, you need to know your goals and find something new and funny in life every day. We bring to your attention an interesting story about an old woman who followed her dream to the end.

Flying over the Alzheimer's nest

Spanish social cartoon "Wrinkles" shown in Moscow

It is not customary to talk about how people "survive" and about senile ailments. And, at the same time, this problem affects every family. Spanish animators undertook to raise a complex topic and talk about it easily and clearly. Director Ignacio Ferras and screenwriter Angel de la Cruz filmed a touching story about life in a nursing home and Alzheimer's disease.

Honor will not be full

Change your attitude towards old age: enough worries for everyone

The II National Conference "From an Aging Society to a Society of All Ages" started on October 9th. The time has come to understand and soberly accept the fact that life really does not end with a pension, but begins, and decide how to equip the life and social security of pensioners of all ages, in any state of health and throughout Russia. The plenary session of the first day of the conference was devoted to the economy of care: what it is, how it happens in Russia and how much it can cost.

The old myth about 10% of the brain

Or the truth about the contents of the skull and simple ways to upgrade it

People are accustomed to believing that somewhere in the unknown depths of the human body, superpowers are hidden, which nature opens only to the elect. In fact, everything is much more prosaic: purposeful efforts and victory over laziness open up an unlimited path to self-improvement. Yes, it is still not too late to realize the potential of not only your child, but also your own brain resources.

live longer

Once again about the theories of aging and the old recipe for youth

In search of a way to stay healthy and beautiful, a person has come a long way from hoping for mythical miracles to researching the DNA chain. However, the answer to the question of how to preserve your body for the longest possible time remains the same as many centuries ago, and only receives diverse scientific justifications.

City without limits

What makes an urban environment suitable for all ages?

The ideal city, like the ideal society, is defined by the adjectives 'equal', 'accessible' and 'open'. This is a space where both a person in a wheelchair and a grandmother with a cane can be active citizens, not limited by the four walls of their apartment. But what is clear and simple in theory is very rarely easily implemented in practice. ChasKor has collected seven elements of a truly barrier-free environment in which people with disabilities feel free.

Of course, it's hard to invest in something that doesn't work. Yes, and it doesn't make much sense. True, in the above example, we did not take into account the main thing - the knowledge of when to expect this result, and, accordingly, rushed to conclusions about the appropriateness of our actions.

To the beat of jazz

Each cell of our body lives in its own mode, so the renewal of our tissues occurs in different time cycles. If the vital rhythms of cells could be described by a melody, most likely, we would not hear a clear march or a rhythmic polka, but a unique jazz composition would sound for us - filled with improvisations and syncopated rhythms.

Our body is constantly being updated. In one day, millions of new cells appear in it, and millions of old ones die. Cells that are in contact with the external environment are updated the fastest. For example, skin cells are updated on average in three weeks, and the cells of the inner walls of the intestine (which make up the smallest villi that absorb nutrients from food masses) - in 3-5 days.

Some life cycles of our body

Receptor cells on the surface of the tongue, which help distinguish food tastes, are renewed every 10 days. Blood cells - erythrocytes - are renewed on average in 120 days, therefore, in order to see a picture of changes in our body, it is recommended to do a general blood test every six months.

Liver cells are renewed in 300-500 days. If you give up alcohol, do not eat fatty and spicy, do not take medication, the liver can be completely cleansed in 8 weeks. By the way, the liver is the only organ in our body that is able to fully recover when 75% of its tissue is lost.

Alveoli (air sacs located at the ends of the bronchi) are renewed within one year, and cells on the surface of the lungs - every 2-3 weeks.

Bone tissue is constantly updated - the fusion of bones after fractures occurs precisely due to its regeneration. But in order for our skeleton to be completely renewed, it takes from 7 to 10 years.

Fingernails grow by 3-4 mm per month, and hair grows by an average of one centimeter. Hair can completely change in a few years, depending on its length. It is believed that in men, hair changes occur in three years, while in women this cycle can reach seven or more years.

The more complex the structure of the tissue and its function, the longer the process of its regeneration. In our body, the nervous tissue is considered the most complex in structure. And although earlier scientists were sure that it was not restored, it has now been revealed that regenerative processes are also possible in it. The brain, the lenses of the eyes and the heart also hold many unsolved mysteries for scientists, since these organs have not yet been fully studied. At the moment, scientists believe that their regeneration process is very complicated and almost impossible.

And who is in charge here?

The brain is the least studied by scientists. Almost all brain cells live with us all our lives and have the same age as we do. It is thanks to the constancy of brain cells that we are able to accumulate experience, acquire information about the world around us, cognize it, draw certain conclusions and use them. At the moment, it has been established that cells are being updated in two areas of the brain. This happens in the olfactory bulb, which is responsible for the perception of smells, and the hippocampus, which is involved in the mechanisms of the formation of emotions, helps to assimilate new information (controls the transition of short-term memory to long-term memory) and navigates in space.

The rate of cell renewal can be influenced by a person's age and the very state of the body: we are sick or healthy at the moment, tired or full of strength and energy. For example, in a person who has Parkinson's disease, the death of old cells is not balanced by the appearance of new ones, and in depression, too few new neurons appear in the hippocampus - i.e. the update process is slow or non-existent.

The regeneration of the body is controlled by our central nervous system and its higher department - the cerebral cortex, which once again confirms the connection between our thoughts and the state of our body. If we believe in ourselves, move forward, look for the necessary solution, then the more likely it is that we help the body recover and renew itself, give birth to strength and interest in life in it.

For centuries, alchemists have been looking for an elixir of youth and a cure for all diseases, but it turns out from birth, each of us has already been endowed with it. Man has only to learn how to use his brains correctly.

Our body is magnificent and ingenious. All we need is not to interfere with his work. And of course, do not feed him any poisonous muck.

After giving up poisons and starting to eat healthy food, after some time we will get a completely healthy body, unless of course we had no very serious diseases before. But my favorite scientists say that even serious diseases can be significantly alleviated and cured over time by switching to proper nutrition.

So that's what I'm all about.

All the cells of our body are constantly updated, and we have, with some periodicity (each organ has its own period), completely new organs.

Leather: the outer layer of the skin that is in contact with the environment is most rapidly updated. Epidermal cells are renewed every 2-3 weeks. The deeper layers are a little slower, but on average, a full cycle of skin renewal occurs in 60-80 days. By the way, interesting information: for the year the body produces about two billion new skin cells.

But then the question arises why the skin of a one-year-old child and a sixty-year-old person looks completely different. There are a lot of unexplored things in our body, but so far it is believed that the skin ages due to the deterioration (over the years) in the production and renewal of collagen, with which this is connected is still under study.

At the moment, it has only been established that such factors as improper and poor (lack of fats and lack of proteins) nutrition, as well as too aggressive environmental influences, are very significant.

They impair the production and quality of collagen. An excess of ultraviolet radiation also negatively affects the regeneration of the skin. But, 20-30 minutes in the sun is considered a therapeutic dose that has a beneficial effect on many processes in the body, including skin renewal.

The cells of the epithelium covering the stomach and intestines come into contact with the most aggressive environment (gastric juices and enzymes that process food) and become thinner, constantly passing through them. They are updated every 3-5 days!

The structure of the mucous membrane of the tongue is very complex, and we will not go into details. The rate of renewal of the various cells that make up the mucous membrane of the tongue (receptors) is different. Simplified we can say that the renewal cycle of these cells is 10-14 days.

Blood- the fluid on which our whole life depends. About half a trillion different blood cells die in the average person's body every day. They must die in time for new ones to be born. In a healthy person, the number of dead cells is equal to the number of newborns. Complete renewal of blood occurs within 120-150 days.

Bronchi and lungs also come into contact with an aggressive environment, therefore they renew their cells relatively quickly. The outer cells of the lungs, which are the first layer of defense against aggressors, are updated in 2-3 weeks. The remaining cells, depending on their functions, are updated at different rates. But in general, a little less than a year is necessary for the body to completely renew lung tissue.

Bronchial alveoli updated every 11-12 months.

Hair grow an average of 1-2 cm per month. That is, after some time we have completely new hair, depending on the length.

The life cycle of eyelashes and eyebrows is 3-6 months.

Nails on the fingers grow at a rate of 3-4 mm per month, the cycle of complete renewal is 6 months. On the toes, the nails grow at a rate of 1-2 mm per month.

Liver, Truly the most magical organ in our body. Not only does it cleanse us all our lives of all the garbage that we put into our bodies, it is also a champion of regeneration. It has been established that even with the loss of 75% of its cells (in the case of surgery), the liver is able to recover completely, and after 2-4 months we have its full volume.

Moreover, at the age of up to 30-40 years, it regenerates the volume even with a vengeance - by 113%. With age, liver recovery occurs only by 90-95%.

Full renewal of liver cells occurs in 150-180 days. It has also been established that if you completely abandon toxic products (chemicals, drugs, fried foods, sugar and alcohol), the liver is independently and completely (!) Cleared of harmful effects in 6-8 weeks.

Our health largely depends on the health of the liver. But even such a hardy organ as the liver, we (try) can kill. A large amount of sugar or alcohol can cause irreversible consequences in the liver in the form of cirrhosis.

Cells of the kidney and spleen updated every 300-500 days.

Skeleton Our body produces hundreds of millions of new cells every day. It constantly regenerates, and in its structure it has both old and new cells. But a complete cellular renewal of the bone structure occurs in 7-10 years. With significant nutritional imbalances, cells are produced much less and of poorer quality, and as a result, over the years, we have such a problem as osteoporosis.

Cells of all types of muscle tissue completely updated in 15-16 years.

Heart, eyes and brain is still the least studied by scientists.

For a very long time it was believed that the muscles of the heart are not updated (unlike the rest of the muscle tissue), but recent discoveries have shown that this is a delusion, and the muscle tissue of the heart is updated in the same way as the rest of the muscles.

Studies have just begun, however, according to preliminary data, it is known that the full heart muscle renewal occurs approximately (exact data is not yet available) for 20 years. That is 3-4 times in an average life.

The mystery is still the fact that eye lens is not updated at all, or rather, why the lens is not updated. Only the cells of the cornea of the eye are restored and renewed. The update cycle is quite fast - 7-10 days. In case of damage, the cornea is able to recover in just a day.

However, this does not negate the fact that the cells of the lens are never updated at all! The central part of the lens is formed at the sixth week of intrauterine development of the fetus. And for the rest of your life, new cells “grow” to the central part of the lens, which makes it thicker and less flexible, worsening the quality of focusing over the years.

Brain- this is the riddle of riddles ...

The brain is the least understood organ in our body. Of course, this is associated with a number of objective factors. The brain of a living person is very difficult to study without harming it. Experiments on humans are forbidden in our country (at least officially). Therefore, studies are carried out on animals and terminally ill human volunteers, which is not at all equivalent to a healthy, normally functioning person.

Until recently, it was believed that brain cells never renew themselves. In principle, things are still there. The brain that controls our entire most complex system called the body, the brain that gives signals for regeneration to all our organs, does not renew itself at all ... Hmm.

Back in the 60s of the last century, Joseph Altman discovered neurogenesis (the birth of new neurons) in the thalamus and cerebral cortex. The scientific world, as usual, was very skeptical about this discovery and forgot about it. In the mid-80s, this discovery was "rediscovered" by another scientist, Fernando Notteboom. And again silence.

But since the end of the 90s of the last century, full-scale studies of our brains have finally begun.

At the present moment (in the course of the latest research) several discoveries have been made. It has already been reliably established that the hippocampus and the olfactory bulb still regularly renew their cells. In birds, lower vertebrates, and mammals, the rate of emergence of new neurons is quite high. In adult rats, approximately 250,000 new neurons are formed and replaced within a month (this is approximately 3% of the total).

The human body also renews the cells of these parts of the brain. It has also been established that the more active the physical and brain activity, the more actively new neurons are formed in these areas. But it is still under study. Wait-sir…

Over the past 20 years, science has made tremendous strides in understanding our nutrition and our health. We finally found out that a big role in the correct Proper nutrition plays a role in the functioning of the organs. It has been reliably clarified - what we need to eat and what we should not eat if we want to be healthy. But in general? What comes out in general? And it turns out that “in detail” we are updated without stopping, all our lives. So what makes us get sick, grow old and die?

We fly into space, we think about the conquest and colonization of other planets. But at the same time, we know so little about our body. Scientists, both in ancient times and in modern times, have absolutely no idea why, with such a huge ability to renew, we grow old. Why wrinkles appear and muscle condition worsens. Why do we lose flexibility and our bones become brittle. Why do we go deaf and stupid ... No one can say anything intelligible, as before.

Some say that aging is in our DNA, but this theory has no evidence base to support it.

Others believe that aging is inherent in our brain and psychology, that we, as it were, force ourselves to grow old and die. That our subconsciousness contains programs of aging. It's just a theory without any evidence or evidence.

Still others (very recent theories) believe that this is due to the "accumulation" of certain mutations and damage in mitochondrial DNA. But they don't know why these damages and mutations accumulate.

That is, it turns out that, contrary to Comrade Darwin's theory of evolution, cells, renewing themselves again and again, renew a worsened version of themselves, instead of an improved one. Strange...

Optimistic "alchemists" believe that we are endowed with the elixir of youth from birth, and there is no need to look for it on the side. He is within us. We just need to choose the right keys to our body and learn how to properly and fully use our brain.

And then our body will be, if not immortal, then very, very long-lived!

Let's feed our body properly. We will help him a little, or rather, we will not interfere with him with all sorts of poisons, and in return he will thank us with good work and a long, HEALTHY life! published

Yul Ivanchey

P.S. And remember, just by changing your consumption, we are changing the world together! © econet

Copy the code and paste it on your blog:

admin/all-yoga.ru

It is known that the cells in our body are renewed. But how does it happen? And if the cells are constantly being renewed, then why does old age come, and not eternal youth last?

According to many psychologists, aging occurs due to the mental programs that have been instilled in us since childhood.

Here we consider the timing of the renewal of specific organs and tissues, which are shown in the figures. Although everything is written there in such detail that this commentary may be unnecessary.

Renewal of organ cells

Brain

Brain cells live with a person throughout his life. But if the cells were updated, the information that was embedded in them would go with them - our thoughts, emotions, memories, skills, experience.

Wrong way of life - smoking, drugs, alcohol - all this to one degree or another destroys the brain, killing part of the cells.

And yet, in two areas of the brain, cells are being renewed.

One of them is the olfactory bulb, which is responsible for the perception of smells.

The second is the hippocampus, which controls the ability to assimilate new information in order to then transfer it to the "storage center", as well as the ability to navigate in space.

Heart

Lungs

For each type of lung tissue, cell renewal occurs at a different rate. For example, the air sacs at the ends of the bronchi (alveoli) regenerate every 11-12 months.

But the cells located on the surface of the lungs are updated every 14-21 days. This part of the respiratory organ takes on most of the harmful substances coming from the air we breathe.

Bad habits (primarily smoking), as well as a polluted atmosphere, slow down the renewal of the alveoli, destroy them and, in the worst case, can lead to emphysema.

Liver

It is the only such organ in our body.

Intestines

Skeleton

The bones of the skeleton are updated continuously, that is, at every moment in the same bone there are both old and new cells. It takes about ten years to completely renovate the skeleton.

This process slows down with age, as bones become thinner and more fragile.

Renewal of body tissue cells

Hair

Hair grows an average of one centimeter per month, but hair can completely change in a few years, depending on the length. For women, this process takes up to six years, for men - up to three.

Eyebrow and eyelash hairs grow back in six to eight weeks.

Eyes

Language

Smoking and oral infections weaken and inhibit this ability, as well as reduce the sensitivity of taste buds.

Leather

The surface layer of the skin is renewed every two to four weeks. But only if the skin is provided with proper care and it does not receive an excess of ultraviolet radiation.

Smoking also has a negative effect on the skin - this bad habit accelerates skin aging for two to four years.

Nails

The most famous example of organ renewal is nails. They grow back 3-4 mm every month. But this is on the hands, on the legs the nails grow twice as slowly.

The nail on the finger is completely renewed on average in six months, on the toe - in ten.

Moreover, on the little fingers, the nails grow much more slowly than the others, and the reason for this is still a mystery to physicians.

The use of drugs slows down the recovery of cells throughout the body!

Now you have realized what affects the renewal of body cells?

Draw your own conclusions!

SEND:


Follow @chaskor

We all will die

Is old age possible without disease?

mother for grandson

What to do if a grandmother tries to raise your child in her own way

Active life in old age

What is aging and how to grow old with pleasure

Aging is inevitable. Growing up is selective.

Old people usually do not regret what they have done, they mourn what they did not have time to do.

Flying over the Alzheimer's nest

Spanish social cartoon "Wrinkles" shown in Moscow

Honor will not be full

Change your attitude towards old age: enough worries for everyone

The old myth about 10% of the brain

Or the truth about the contents of the skull and simple ways to upgrade it

live longer

Once again about the theories of aging and the old recipe for youth

City without limits

What makes an urban environment suitable for all ages?

HOW OLD ARE YOU?

Do not rush to answer this seemingly simple question, because the Swedish neurologist Jonas Friesen answered it for you: every adult is on average fifteen and a half years old. If according to your passport, for example, you are sixty, then the lenses of your eyes are on average 22 weeks older (!), Your brain is about the same age as you, but your skin is only two weeks old. Muscle cells of the intercostal muscles in people aged 37-40 years, as it turned out, have an average age of 15.1 years, and intestinal cells (except for the epithelium) - 15.9 years.

From one popular science book to another, the statement wanders: our body is almost completely renewed in seven years. Old cells gradually die off, their places are taken by new ones.

The cells are indeed being updated, but no one really knows where the mythical number “seven” came from. For some cells, the renewal period is set more or less precisely, namely: 150 days for blood cells, the gradual replacement of which can be followed after a blood transfusion, and two weeks for skin cells that appear in its deep layers, gradually migrate to the surface, die and peel off.

Receptor cells on the surface of the tongue, which help distinguish food tastes, are renewed every 10 days. Blood cells - erythrocytes - are updated in an average of 120 days, therefore, in order to see a picture of changes in our body, it is recommended to do a general blood test every six months.

Alveoli (air sacs located at the ends of the bronchi) are renewed within one year, and cells on the surface of the lungs - every 2-3 weeks.

Bone tissue is constantly updated - the fusion of bones after fractures occurs precisely due to its regeneration. But in order for our skeleton to be completely renewed, it takes from 7 to 10 years.

Friesen, as a neurologist, is, of course, most interested in the brain. It is known from animal studies, as well as one patient who was dying of cancer and agreed to have a weakly radioactive isotope injected into his brain, that after birth, new neurons arise only in two areas - in the hippocampus and around the ventricles of the brain.
So far, the age of only a few parts of the brain has been measured with the new method. According to Friesen, the cells of the cerebellum are 2.9 years younger, on average. The cerebellum is known to be responsible for coordination of movements, and it gradually improves with age in a child, so it can be assumed that by about three years the cerebellum is completely formed. The cerebral cortex has the same age as the person himself, that is, new neurons do not appear in it throughout life. The rest of the brain is still being studied.

Measurement of the age of individual tissues and organs is not carried out out of curiosity. Knowing the rate of cell turnover, we may be able to treat cataracts, obesity, and some nervous diseases. In 2004, researchers from Columbia University (USA) found that depression in the hippocampus produces too few new neurons, and some drugs for depression stimulate this process. Alzheimer's disease is also associated with insufficient neurogenesis in the hippocampus. In Parkinson's disease, as far as we know, the death of old cells is not balanced by the appearance of new ones.

Knowing how often people develop new fat cells will help treat obesity. So far, no one knows whether this disease is associated with an increase in the number or size of fat cells. Knowing the frequency of appearance of new cells in the liver and pancreas will allow the creation of new methods for the diagnosis and treatment of liver cancer and diabetes.

The question of the age of the muscle cells of the heart is very relevant. Experts believe that dying cells are replaced by fibrous connective tissue, so the heart muscle weakens over time. But there is no exact data. Friesen and his team are now working on determining the age of the heart.

Americans have learned to measure the age of the lens of the eye. Its central part is formed from transparent cells at the sixth week of the embryo's life and remains for life. But new cells are constantly being added to the periphery of the lens, making the lens thicker and less flexible, which affects its ability to focus the image. By studying this process, we may find ways to delay the onset of cataracts by five years, says Bruce Buchholz of the Livermore National Laboratory (USA), where mass spectrometric measurements are made of samples supplied from the University of California and Friesen's laboratory.

But if many of the “details” of our body are constantly being updated and, as a result, turn out to be much younger than their owner, then some questions arise. For example, if the top layer of skin is only two weeks old, why doesn't it remain smooth and pink all its life, like a two-week-old baby? If the muscles are about 15 years old, why is a 60-year-old woman less agile and mobile than a 15-year-old girl? The reason is in mitochondrial DNA. It accumulates damage faster than the DNA of the cell nucleus. That is why the skin ages over time: mutations in mitochondria lead to a deterioration in the quality of its important constituent material, collagen.

According to the New Scientist magazine