Rhythms of human body renewal
Aging is an inevitable process and pleasing no one. Not only women, but also men are increasingly interested in anti-aging cosmetics and procedures to hide their true age. Not realizing that artificially stretched skin will not help lose a dozen years. At the same time, rejuvenation is inherent in us by mother nature, and all that is needed is to adhere to a healthy lifestyle, so as not to disturb the natural processes of organ renewal.
Did this happen to you - you decided to lead a healthy lifestyle: abandoned bad habits, started exercising regularly, eating balanced, using natural cosmetics, but a week passed, followed by a second, and visible result (the hair did not become healthy and silky, nails still break, pimples do not disappear) and there is no inner calm?
It is known that cells in our body are updated. But how is the renewal of body cells? And if the cells are constantly updated, then why does old age come, and not eternal youth last? And then, succumbing to the frustration ("Nothing will help me anymore"), give up, and I want to go back to the old one, hoping for "miraculous" pills and plastic surgery ("Oh, they will tone the body!").
Brain - 20 years old
The brain is the most important and one of the most vulnerable organs of our body. And he begins to age before everyone else. This process is characterized by a decrease in the number of nerve cells, the consequence of which is a decrease in memory, coordination, speech skills and so on. By the age of forty, the rate of loss of neurons can reach 10,000 cells per day, and in people suffering from various mental disorders - even faster.
Another age-related loss of our brain is a substance between neurons called synapse. It ensures the transfer of information from one cell to another, and the reduction in its volume over the years also affects the functioning of our brain.
Brain cells live with a person throughout his life. But if the cells were updated, the information that was embedded in them would leave with them — our thoughts, emotions, memories, skills, experience. Wrong lifestyle - smoking drugs, alcohol - all this to one degree or another destroys the brain, killing part of the cells.
One of them is the olfactory bulb, which is responsible for the perception of odors. The second is the hippocampus, which controls the ability to absorb new information, then transfer it to the "storage center", as well as the ability to navigate in space.
Stomach - 55 years old
The main sign of a healthy stomach is the balance between harmful and beneficial flora, which can be disturbed due to improper nutrition, or simply over time. The number of beneficial bacteria begins to decline rapidly after 55, which leads to an increased risk of stomach infections, constipation and poor digestion.
Breast - 35 years old
At this age, even the owners of the most magnificent forms begin to have problems with the bust. The fact is that over time, the amount of adipose tissue in the female breast decreases, the skin loses its elasticity, and the breast begins to sag. But it’s much worse that with age, tissue cells can mutate and turn into cancerous, so after 35 women it is better to visit a mammogram more often.
Bladder - 65 years old
Aging this organ threatens you with the inconvenience caused by constant “urges”, and possibly even incontinence. Women are especially susceptible to these problems: their bladder volume is halved by the age of 70 compared to, for example, the 35th, and even the muscles in the inguinal region lose their tone. As a result, a woman has to visit the "ladies' room" almost every 20 minutes, but the bladder is not completely empty, and this many times increases the risk of developing some kind of infection.
Heart - 40 years old
The fact that heart cells also have the ability to update, it became known recently. According to researchers, this happens only once or twice in a lifetime, so it’s extremely important to maintain this organ.
The aging of this organ is marked by the fact that the blood in our body accelerates much more slowly than before. Vessels become less elastic, patency of arteries is reduced by cholesterol plaques, the risk of earning a heart attack increases at times every year.
Lungs - 20 years
From this time, the volume of your lungs begins to gradually decrease. In addition, the entire muscle system that controls our breathing gradually weakens, and as a result, by the age of 40, some unfortunate people begin to literally suffocate. By the age of 70, the volume of air that we can breathe in at one time is reduced by about half compared to the 30s.
For each type of lung tissue, cell renewal occurs at a different rate. For example, the air sacs that are located on the ends of the bronchi (alveoli) are regenerated every 11 to 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 - 70 years
This is perhaps the most age-resistant organ in the entire human body. Its cells have an amazing ability to recover quickly and at low cost, so the whole organ can literally grow from one fragment in a few months. Using this magical property, transplantologists often take the organs of 70-year-old donors to treat much younger patients.
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 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. This is the only such organ in our body.
Of course, such endurance of the liver is possible with your help to this body: the liver does not like fatty, spicy, fried, smoked foods. In addition, her work is very complicated by alcohol and most drugs. And if you do not pay attention to this organ, it will cruelly avenge its owner with terrible diseases - cirrhosis or cancer. (By the way, if you stop taking alcohol for eight weeks, the liver is able to completely clear).
The intestinal walls 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, therefore they do not live long. The terms for updating them are three to five days.
Skeleton - 35 years old
Throughout our lives, the cells of our bones are gradually renewed. In children, this process takes a couple of years, in adults and the elderly it can stretch for tens. Renewal rate begins to fall at about 35, which leads to weakening of bones, an increased risk of fractures, slow healing. In addition, over the years, our skeleton literally shrinks in size, so by the age of 80 a person can lose up to 5 centimeters of growth.
The bones of the skeleton are updated continuously, that is, at every moment in time in the same bone there are both old and new cells. A complete skeleton upgrade takes about ten years. This process slows down with age, when the bones become thinner and more fragile.
Kidneys - 50th Anniversary
At the age of 50, the tissues that serve our body as a kind of filter and remove all harmful substances from our blood begin to age and shrink in volume. The effectiveness of the kidneys from 30 to 70 years falls in half. In fact, this leads to urinary incontinence and pain during urination.
Prostate - 50th Anniversary
The prostate does not contract over time, but, on the contrary, grows, absorbing more and more testosterone hormone. The normal size of this organ is about the size of a walnut, with age it can increase to an orange. This again leads to problems with urination, which, according to statistics, plague about half of all men older than 50. At the same time, 40-year-olds are almost unfamiliar with such difficulties.
Teeth - 40 years old
The salivary glands work worse and worse, saliva is not able to wash away all harmful bacteria from the surface of the teeth, so the teeth and gums become much more susceptible to any infection. Gum infections are a common problem among those over 40.
Muscles - 30 years old
If you regularly play sports, you have a chance to independently check how your muscle condition changes after 30. It becomes more difficult to train, and the relief no longer appears after a couple of weeks of training from time to time. But these are all flowers: doctors say that after 40 years, our body begins to lose from 0.5 to 2% of muscle mass per year. However, constant exercise will help you avoid this.
Reproductive system - 35 years
In women, the productivity of the genital organs begins to fall after 35, along with it the chances of becoming pregnant are reduced. From the same age, the quality of male sperm deteriorates, therefore, women conceived with a man after 35 have a much higher risk of miscarriage.
Hair - 30 years
Hair grows on average one centimeter per month, but hair can completely change in a few years, depending on the length. In women, this process takes up to six years, in men - up to three. Eyebrow and eyelash hairs grow back in six to eight weeks.
Human hair can grow for 3 years, after which it falls out, giving place to another. In men, this process is affected by the amount of testosterone, which begins to decline with age. As a result, the hair follicles gradually shrink, the hair becomes thinner and eventually stops growing. As for gray hair, it appears due to a decrease in the amount of pigment in the follicle, and each new hair grows lighter than the previous one.
Eyes - 40 years old
In such a very important and fragile organ as the eye, only corneal cells are able to renew. Its top layer is replaced every 7 to 10 days. If the cornea is damaged, the process occurs even faster - it is able to recover in a day.
For most 40-year-olds, glasses or lenses are commonplace. The most common ailment that catches our eyes in old age is farsightedness, which develops due to the weakening of the eye muscles and the loss of the eye's ability to concentrate.
10,000 receptors are located on the surface of the tongue. They are able to distinguish between the tastes of food: sweet, sour, bitter, spicy, salty. Tongue cells have a fairly short life cycle of ten days.
Smoking and oral infections weaken and inhibit this ability, as well as reduce the sensitivity of taste buds.
Leather - 20 years
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 negatively affects the skin - this bad habit accelerates skin aging for two to four years.
Skin aging is explained by a decrease in the release of collagen and elastin - substances that support skin elasticity and help it recover from injuries and stretch marks. In addition, the skin itself is updated much more slowly, changes color, becomes thinner. Smoking can accelerate this process and constant direct exposure to the sun.
The most famous example of organ renewal is nails. They grow by 3-4 mm every month. But this is on the hands, on the feet the nails grow twice as slow. Completely a fingernail is updated in an average of six months, on a toe - in ten.
Moreover, on the little fingers, nails grow much slower than the rest, and the reason for this is still a mystery to doctors.
Voice - 65 years old
With age, the voice becomes quieter, a hoarseness appears. This is explained by the fact that the soft tissues of the larynx lose their elasticity and tone. As a result, a woman may find that she began to talk almost in bass, and a man, on the contrary, will begin to “sound” a little higher than before.
Hearing - 55 years
According to statistics, almost half of people over 60 experience serious hearing problems and are even deaf. The reason is the loss of the so-called hair cells, which pick up the vibration of the air and send information to the brain.
Taste and smell - 60 years
In youth, the number of taste buds in the tongue reaches about 10,000. By age, it is reduced by about half. This is also the case with the sense of smell.
How old do you feel inside?
Not by passport, but by inner feelings? Many of my friends say that they are 18-25 years old (according to their passport they are more than 50). One of my acquaintances (let's call her Luda) - bioenergetics - always says that she feels 15 years old!
And I was very surprised to read that the Swedish neurologist Jonas Friesen found: for every adult, on average, fifteen and a half years! So Luda just perfectly knows and feels her body!
In the literature, I very often find the statement that our body is almost completely renewed every seven years. Old cells gradually die, and new cells appear in their place. But where did this magic figure “seven” come from, I can’t understand.
For some cells of our body, the renewal period can be set more or less accurately, namely: 150 days for blood cells, the gradual replacement of which is observed after blood transfusion, as well as 14 days for skin cells. Skin cells nucleate in its deep layers, gradually emerge on the surface, where they die and exfoliate.
It is difficult to conduct experiments on a person to determine the life span of cells, so they try, as always, on rats and mice. To do this, they are given with food or injected with special radioactive additives - labeled nucleotides, which are the building blocks of DNA.
New cells, suspecting nothing, embed these labels in their structure. The number of labeled cells in different organs or tissues of the body can be measured and the fraction of those new cells that were born during the time that has passed since the mouse received radioactive DNA can be calculated.
You can’t apply such a method to a person. Some researchers have tried to determine the age of human cells by the length of the telomeres (these are the final sections of the chromosomes). But this method did not give reliable results, since some cells began to “grow” telomeres after division.
Finally, the Swedish researcher Jonas Friesen decided to use the method of archaeologists and historians who determine the age of objects containing organic matter by the carbon-14 (14C) isotope. I will not bore you with the theory (although it is very interesting), but this method failed miserably, since it reliably works only for long periods of time, since the concentration of this isotope is very low.
But Friesen was struck by the idea that from 1955 to 1963, due to nuclear weapons tests, the concentration of the 14C isotope in air increased and was twice the norm. Over time, it is declining and is now back to normal. Friesen believed that his method allows you to determine the age of any cell born between 1955 and 1990.
Friesen in 2005 published preliminary results of his research. He confirmed that the cells that are in direct contact with the external environment - these are the epidermal cells of the skin - live for two weeks, as I wrote earlier, and the intestinal epithelial cells that regularly interact with food live only 5 days.
Red blood cells, or red blood cells, have a lifespan of 150 days (according to Friesen).
But if many of the “details” of our body are constantly updated and as a result are much younger than their owner, then some questions arise.
For example, why does the skin not remain whole life smooth and pink, like a baby, if the top layer of skin is always two weeks old?
If the muscles are about 15 years old, then why is a woman at 60 not so flexible and mobile as a girl of 15?
Friesen saw the answers to these questions in the DNA in the mitochondria (this is a part of each cell). She quickly accumulates various damage. That is why 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 those mental programs that have been inherent in us since childhood. But more about this will be discussed in other articles.
Here we will consider the timing of updating specific organs and tissues, which are shown in the figures. Although there everything is written in such detail that maybe this comment is unnecessary.
How old are you?
Take your time to answer this simple, as it seems, question, because the Swedish neurologist Jonas Friesen answered you for it: 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 yours, but your skin is only two weeks old.
A statement wanders from one popular science book to another: our body is almost completely renewed in seven years. Old cells gradually die, their places are replaced by new ones.
The cells are really being updated, but no one really knows where the mythical figure “seven” came from. For some cells, the renewal period is set more or less accurately, namely: 150 days for blood cells, the gradual replacement of which can be traced after blood transfusion, and two weeks for skin cells that appear in its deep layers, gradually migrate to the surface, die and exfoliate.
Experiments to measure cell life have been going on for about half a century, but only in rats and mice. Labeled (radioactive) nucleotides, the building blocks of DNA, are given to animals intravenously or given as food. New cells incorporate these tags into their genetic material. Their number in different tissues and organs can be measured and the proportion of cells that were born during the time elapsed after the introduction of radioactive DNA can be calculated.
Of course, this method is not applicable to humans. They tried to determine the age of human cells by the length of the telomeres - the terminal sections of the chromosomes. Telomeres are shortened at each cell division. But it was not possible to develop on this basis a reliable method for determining the age of cells, especially since some cells, as it turned out, are able to “grow” telomeres after division.
The Swedish researcher Jonas Friesen decided to use the method of archaeologists and historians who can determine the age of objects containing organic matter by carbon-14 (14C). This rare and weakly radioactive carbon isotope is constantly formed in the stratosphere, where cosmic rays knock out one proton from the nuclei of nitrogen atoms. Gradually (half-life of 5730 years), 14C again turns into nitrogen. During photosynthesis, plants absorb 14C from the atmosphere and incorporate it into sugar molecules. Animals eat plants, and therefore all living things contain a little of this isotope. About one in a trillion carbon atoms in your body is carbon-14 in place of regular carbon-12. When the body dies, it ceases to receive a new 14С, and the one that has already been accumulated during its lifetime gradually disintegrates. This decay, proceeding at a known speed, allows us to determine how long living matter became dead. For example, when a tree was cut down, from which a prehistoric boat was made, or when a calf was slaughtered to make parchment for manuscript from its skin. However, due to the extremely small amounts of the isotope and the slowness of its decay, the method is suitable only for large periods of time.
But here, as they say, there would be no happiness, but misfortune helped. Friesen realized that to determine the age of individual cells, you can use the not-so-short period of time when, due to human activity, the amount of 14C in the atmosphere has increased significantly. From 1955 to 1963, nuclear weapons tests introduced large amounts of isotope into the atmosphere. At the peak of these tests, in 1963, the concentration of 14C in the air was twice the norm. Its content has been repeatedly measured and continues to be measured in various parts of the Earth, so that a curve has been drawn up for a sharp increase and a gradual decrease in this value. Now the content of the isotope in the air has almost returned to normal, as it is gradually absorbed by the biosphere and, together with carbon dioxide, dissolves in the waters of the oceans. But Friesen believes that his method allows you to determine the age of any cell born between 1955 and 1990.
How dangerous is the breakdown of radioactive carbon in the body? In the human body weighing 75 kilograms, about 300 trillion trillions (3 × 1026) of carbon atoms, of which only 350 trillion (3.5 × 1014), are carbon 14C. Apart from the mineral component (mainly bones) and it is assumed that 14C is distributed evenly over the rest of the body tissues, then there are an average of 11 14C atoms in each cell. DNA by weight makes up about 1% of the cells. The 14C isotope decays so rarely that if you take an individual cell selected at random, then one 14C atom in its DNA will decay every 18,000 years (we take exactly the 14C that is included in the DNA, since changes in the composition of this molecule can be important for the health of the body and its offspring). If you assume that you will live 70 years, then the chances that any particular individual cell in your body will ever experience an “atomic explosion” of one carbon atom in its DNA are 1 versus 260.
When it appears, the cell receives a set of chromosomes that remain with it throughout its life. Therefore, the content of 14C in DNA is directly proportional to its content in the atmosphere at the time when this cell appeared, minus a small amount that disappeared as a result of natural decay. Analyzes are performed by atomic mass spectrometry.
In 2005, Friesen and his colleagues published preliminary results of cell analyzes of people living during the peak of 14C. As expected, the shortest life span of cells that are in direct contact with the external environment is skin epidermal cells (two weeks, as we mentioned) and intestinal epithelium cells that are constantly abraded by passing food masses (5 days). Red blood cells, according to Friesen, live 150 days. The muscle cells of the intercostal muscles in people 37-40 years old, as it turned out, have an average age of 15.1 years, and intestinal cells (except the epithelium) - 15.9 years.
Friesen as a neurologist is, of course, most interested in the brain. From studies conducted on animals, as well as on one patient dying of cancer and agreeing to introduce a weakly radioactive isotope into his brain, it is known that after birth new neurons arise in only two areas - in the hippocampus and around the ventricles of the brain.
So far, the new method has measured the age of only a few areas of the brain. According to Friesen, cerebellar cells are 2.9 years younger than humans themselves. The cerebellum is known to be responsible for the coordination of movements, and it gradually improves with age in the child, so it can be assumed that by about three years the cerebellum is finally formed. The cerebral cortex has the same age as the person himself, that is, new neurons do not appear in it throughout life. The remaining parts of the brain are still being studied.
Measuring the age of individual tissues and organs is not carried out of curiosity. Knowing the speed of cell turnover, we may learn how to treat cataracts, obesity and some nervous diseases. In 2004, researchers from Columbia University (USA) found that with depression in the hippocampus there are 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 is known, the death of old cells is not balanced by the appearance of new ones.
Knowing how often people get 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 the appearance of new liver and pancreatic cells will create new methods for the diagnosis and treatment of liver cancer and diabetes.
Very relevant is the question of the age of the muscle cells of the heart. 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 group 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 around the periphery of the lens, making the lens thicker and less flexible, which affects its ability to focus the image. Having studied this process, we may find ways to delay the onset of cataract by five years, says Bruce Buchholz from Livermore National Laboratory (USA), where mass spectrometric measurements of samples supplied from the University of California and Friesen's laboratory are performed.
But if many of the “details” of our body are constantly updated and as a result are much younger than their owner, then some questions arise. For example, if the upper layer of the skin is only two weeks old, why doesn’t it remain lifelong smooth and pink, 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 skin ages over time: mutations in mitochondria lead to a deterioration in the quality of its important constituent material, collagen.
Y. FROLOV, “Science and Life” No. 7-2007 (based on the materials of the journal “New Scientist”).
The use of drugs slows the recovery of cells throughout the body! Now you realize what affects the renewal of body cells? Draw conclusions! All the best to you! Comment and write your observations and conclusions!