Rhythms of renewal of the human body
Aging is an inevitable process and does not please anyone. Not only women, but also men are more and more 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 mother nature, and all that is needed is to adhere to a healthy lifestyle in order not to disturb the natural processes of organ renewal.
Have you ever had such a thing - you decided to lead a healthy lifestyle: you gave up bad habits, started to do regular exercises, eat a balanced diet, use natural cosmetics, but a week goes by, followed by a second, and visible result (the hair did not become healthy and silky, nails still break, pimples do not disappear) and internal peace is not observed?
It is known that the cells in our body are updated. But how is the cell renewal of the body? And if the cells are constantly updated, then why does old age come, and does not the eternal youth last? And then, succumbing to frustration (“Nothing will help me anymore”), give up, and I want to return to the old, hoping for “miraculous” pills and plastic surgery (“They will bring the body into a tonus!”).
Brain - 20 years
The brain is the most important and one of the most vulnerable organs of our body. And he begins to grow old before all. This process is characterized by a reduction in the number of nerve cells, the consequence of which is a deterioration of memory, coordination, speech skills, and so on. By the age of forty, the rate of neuron loss 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 the substance between neurons called synapses. It provides the transfer of information from one cell to another, and the reduction of 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, they would leave the information that was in them, our thoughts, emotions, memories, skills, experience. Wrong lifestyle - smoking, drugs, alcohol - all this in one degree or another destroys the brain, killing some 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 in order to transfer it to the “storage center”, as well as the ability to navigate in space.
Stomach - 55 years
The main symptom of a healthy stomach is the balance between harmful and beneficial flora, which can be disrupted both by malnutrition and simply over time. The number of beneficial bacteria begins to decline rapidly after 55, which leads to an increased risk of gastric infections, constipation and poor digestion.
Breast - 35 years
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 volume of adipose tissue in the female breast decreases, the skin loses elasticity, and the breast begins to sag. But it is much worse that with age, the cells of the tissues can mutate and turn into cancer, so after 35 women it is better to visit the mammogram more often.
Bladder - 65 years
The aging of this organ threatens you with 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 with, for example, the 35th, and the muscles in the inguinal region lose their tone. As a result, a woman has to go to the “ladies' room” almost every 20 minutes, but the bladder is not completely emptied, and this greatly increases the risk of developing any infection.
Heart - 40 years
The fact that the cells of the heart also have the ability to update, it became known recently. According to researchers, this happens only once or twice in a lifetime, so it is extremely important to preserve this organ.
The aging of this organ is marked by the fact that the blood through our body accelerates much slower than before. The vessels become less elastic, the arterial permeability is reduced by cholesterol plaques, the risk of earning a heart attack increases many times every year.
Lungs - 20 years
From this date, the volume of your lungs begins to gradually decline. In addition, the entire muscular system that controls our breathing gradually weakens, and as a result, by the age of 40, some unlucky people begin to literally suffocate. By 70, the volume of air that we can breathe in at one time is approximately halved compared to the 30th year.
For each type of lung tissue, cell renewal occurs at a different rate. For example, air sacs that are located at the ends of the bronchi (alveoli) - are revived 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 over most of the harmful substances coming from the air we breathe.
Harmful habits (primarily smoking), as well as a polluted atmosphere, slow down 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 whole human body. Its cells have an amazing ability to recover quickly and at low cost, so an entire organ can literally be grown from a single fragment in a few months. Using this magical property, transplantologists often take organs from 70 year old donors to treat much younger patients.
Liver is a champion in regeneration among the organs of the human body. Liver cells are updated approximately every 150 days, that is, the liver is “reborn” once every five months. It is able to recover completely, even if a person has lost up to two-thirds of the body as a result of the operation. This 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 food. In addition, her work is very difficult alcohol and most of the drugs. And if you do not pay attention to this body, it will cruelly revenge its owner with terrible diseases - cirrhosis or cancer. (By the way, if you stop taking alcohol for eight weeks, the liver can completely clear).
The inside of the intestine is covered with tiny villi that absorb nutrients. But they are under the constant influence of gastric juice, which dissolves food, so they do not live long. The timing of their updates - three to five days.
Skeleton - 35 years
Throughout our life, the cells of our bones are gradually updated. In children, this process takes a couple of years, in adults and old people it can stretch into dozens. The refresh rate starts to drop at about 35, which leads to weakening of the 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 height.
The bones of the skeleton are updated continuously, that is, at each moment in time in the same bone there are both old and new cells. On a complete update of the skeleton takes about ten years. This process slows with age, when the bones become thinner and brittle.
Kidney - 50 years
At 50 years of age, tissues that serve as a filter for our body 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 and falls twice. In fact, this leads to urinary incontinence and pain when urinating.
Prostate - 50 years
The prostate does not contract with time, but, on the contrary, grows, absorbing more and more hormone testosterone. The normal size of this organ is about a walnut, with age it can increase to an orange. Again, this leads to problems with urination, which, according to statistics, pursue about half of all men over 50. At the same time, 40-year-olds have almost no such difficulties.
Teeth - 40 years
Salivary glands are working worse and worse, saliva is not able to wash off all harmful bacteria from the surface of the teeth, so the teeth and gums are much more susceptible to any infection. Gingival infections are a common problem among those over 40.
Muscles - 30 years
If you exercise regularly, you have a chance to check how your muscles change after 30. It becomes more difficult to train, and the relief does not appear 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, regular exercise will help you to avoid this.
The reproductive system is 35 years old
In women, the productivity of the genitals begins to fall after 35, and with it the chances of getting pregnant are also reduced. From the same age, the quality of male sperm is deteriorating, so for women who conceive with a man after 35, the risk of miscarriage is much higher.
Hair - 30 years
Hair grows on average by 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. Eyebrows and eyelashes 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 fall with age. As a result, the hair follicles gradually shrink, hair becomes thinner and eventually stop growing. As for the gray hair, it appears due to the reduction in the amount of pigment in the follicle, and each new hair grows lighter than the previous one.
Eyes - 40 years
In such a very important and fragile organ as the eye, only corneal cells can be renewed. There is a replacement of its upper layer every 7 - 10 days. If the cornea is damaged, the process is even faster - it can recover in a day.
For most 40 year olds, glasses or lenses are common. The most common ailment that overtakes 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 the tastes of food: sweet, sour, bitter, spicy, salty. The cells of the tongue have a rather short life cycle - ten days.
Smoking and infections of the oral cavity 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 has a negative effect on the skin - this bad habit speeds up the aging of the skin by two to four years.
Aging of the skin is due to a reduction in the release of collagen and elastin - substances that maintain skin elasticity and help it recover from injuries and stretch marks. In addition, the skin itself is renewed much more slowly, changes color, becomes thinner. Smoke and constant direct exposure to the sun can accelerate this process.
The most famous example of organ renewal is nails. They grow by 3-4 mm every month. But it is on the arms, on the legs the nails grow two times slower. Completely on the fingernail is updated on average for six months, on the toe - for ten.
Moreover, on the little finger nails grow much slower than the rest, and the reason for this is still a mystery to physicians.
Voice - 65 years
With age, the voice becomes quieter, appears hoarse. 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 with bass, and a man, on the contrary, will start to “sound” a little higher than before.
Hearing - 55 years
According to statistics, almost half of people over 60 have serious hearing problems and even are deaf. The reason - the loss of the so-called hair cells, which capture the vibration of the air and send information to the brain.
Taste and smell - 60 years
In youth, the number of taste receptors in the tongue reaches about 10,000. By old age, it is reduced by about half. The same is true of smell.
How old do you feel inside?
Not according to your passport, but according to your inner feelings? Many of my friends say that they are 18-25 years old (according to their passport, they are over 50). One of my friends (let's call her Lyuda) - bioenergy, 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 person, on average, fifteen and a half years! So Luda just perfectly knows and feels her body!
In the literature, I often see the statement that our body is almost completely updated every seven years. Old cells gradually die off, and new cells appear in their place. But where did this magic number “seven” come from, I cannot 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 originate in its deep layers, gradually emerging on the surface, where they die and peel off.
It is difficult to conduct experiments on the determination of cell life on a person, so they try, as always, on rats and mice. To do this, they are given with food or administered intravenously with special radioactive additives - labeled nucleotides, which are the building blocks of DNA.
New cells, not suspecting anything, embed these labels in their structure. The number of labeled cells in different organs or tissues of the body can be measured and the proportion of those new cells that were born during the time that the radioactive DNA was obtained by the mouse was calculated.
You will not apply such a method to a person. Some researchers tried to determine the age of human cells by the length of telomeres (these are the final parts of 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 isotope (14C). I will not bore you with theory (although it is very interesting), but this method failed miserably, as it reliably works only for long periods of time, since the concentration of this isotope is very low.
But Frisen conceived the idea that from 1955 to 1963 due to tests of nuclear weapons, the concentration of the 14C isotope in the air increased and was twice as high as the norm. Over time, it decreases and has now returned to normal indicators. Friesen believed that his method allows to determine the age of any cell born between 1955 and 1990.
Friesen in 2005 published the preliminary results of their research. He confirmed that cells that are in direct contact with the external environment — and these are skin epidermis cells — will live for two weeks, as I wrote earlier, and intestinal epithelial cells, which 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 turn out to be much younger than their owner, then some questions arise.
For example, why the skin does not remain all life smooth and pink, like a baby, if the top layer of skin is always two weeks?
If the muscles are about 15 years old, then why is a woman at 60 not as flexible and agile as a girl of 15?
Answers to these questions Friesen saw in the DNA in the mitochondria (this is part of each cell). She quickly accumulates various damage. That is why the skin ages with time: mutations in mitochondria lead to a deterioration in the quality of such an important composite material of the skin, like collagen.
According to many psychologists, aging is due to those mental programs that are incorporated in us since childhood. But more about this conversation will go to other articles.
Here we consider the timing of the update of specific organs and tissues, which are shown in the figures. Although there everything is written in such detail that it may be unnecessary commenting.
How old are you?
Do not rush to answer this simple, as it seems, question, because Swedish neurologist Jonas Friesen answered it for you: on average, every adult person is fifteen and a half years old. If you pass your passport, for example, sixty, then the lenses of your eyes are on average 22 weeks older (!), The brain is about your age, but your skin is only two weeks old.
From one non-fiction book to another, a statement wanders: our body is almost completely renewed in seven years. Old cells gradually die off, their places are occupied by new ones.
The cells are indeed being updated, but where the mythical figure “seven” came from, nobody really knows. 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 traced after blood transfusion, and two weeks for skin cells that appear in its deep layers, gradually migrate to the surface, die and peel off.
Experiments on the measurement of cell life span have been conducted for about half a century, but only in rats and mice. Animals are injected intravenously or given in food labeled (radioactive) nucleotides - the building blocks of DNA. New cells embed these labels in 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 man. We tried to determine the age of human cells by the length of telomeres - the final sections of chromosomes. Telomeres are shortened with each cell division. But it was not possible to work out a reliable method for determining the age of the cell on this basis, especially since some cells, as it turned out, are able to “grow” telomeres after division.
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 from the nuclei of nitrogen atoms by one proton. Gradually (half-life 5730 years) 14C again turns into nitrogen. In the process of photosynthesis, plants absorb 14C from the atmosphere and embed it in 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 organism dies, it ceases to receive a new 14C, and the one that has already accumulated during its life gradually disintegrates. This decay, going with a certain speed, and allows you to determine how long living matter has become dead. For example, when a tree was cut down, from which a prehistoric boat was made, or when a calf was slaughtered to make a parchment for manuscript from its skin. However, due to 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, one can use the not so short period of time when, due to human activity, the amount of 14C in the atmosphere has greatly increased. From 1955 to 1963, tests of nuclear weapons introduced large quantities of isotope into the atmosphere. At the peak of these tests, in 1963, the 14C concentration in the air was twice as high as normal. Its content was repeatedly measured and continued to be measured in the most diverse regions of the Earth, so that a curve of sharp growth and a gradual fall of this magnitude was drawn up. Now the isotope content in the air is almost back to normal, as it is gradually absorbed by the biosphere and, together with carbon dioxide, dissolves in the waters of the World Ocean. But Friesen considers his method 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 trillion (3? 1026) carbon atoms, of which only 350 trillion (3.5? 1014) - carbon 14С. Apart from the mineral component (mainly bones) and assuming that 14C is evenly distributed throughout the rest of the body tissues, then on average, there are only 11 14C atoms in each cell. DNA by weight is about 1% of the cells. The 14C isotope decays so rarely that if you take a single cell selected at random, then one atom of 14C will decay as part of its DNA once 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 health of the body and its offspring). If you assume that you live for 70 years, then the chances that a particular individual cell in your body will ever experience an atomic explosion of one carbon atom in its DNA is 1 against 260.
With its appearance, the cell receives a set of chromosomes that remain with it all 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 staff published the preliminary results of cell analyzes of people who lived during the peak of 14C. As expected, the life span of cells that are in direct contact with the external environment is the shortest — the epidermis cells of the skin (two weeks, as we mentioned), and the intestinal epithelium cells, which are constantly abraded by passing food masses (5 days). Red blood cells, according to Friesen, live 150 days. 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 for the epithelium) have 15.9 years.
Frisena as a neurologist most of all, of course, is interested in the brain. From studies conducted on animals, as well as on one patient dying from cancer and agreeing to inject a weakly radioactive isotope into his brain, it is known 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 areas of the brain has been measured. According to Frisen, the cells of the cerebellum are younger by 2.9 years younger than the person himself. 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 completely formed. The cerebral cortex has the same age as the person himself, that is, throughout life, new neurons do not appear in it. The rest of the brain is still being studied.
Measuring the age of individual tissues and organs is not out of curiosity. Knowing the rate of cell turnover, we may learn to treat cataracts, obesity, and some nervous diseases. In 2004, researchers at Columbia University (USA) found that with depression in the hippocampus, too few new neurons arise, 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 new fat cells appear in people will help treat obesity. While no one knows whether this disease is associated with an increase in the number or size of fat cells. Knowledge of the frequency of appearance of new cells of the liver and pancreas will allow you to create new methods for the diagnosis and treatment of liver cancer and diabetes.
A very topical issue is about the age of the muscle cells of the heart. Experts believe that the 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 in the sixth week of the embryo and remains for life. But along the periphery of the lens, new cells are constantly added, making the lens thicker and less flexible, which affects its ability to focus the image. After studying this process, we may find ways to delay the onset of cataracts by five years, says Bruce Buchholz from the Livermore National Laboratory (USA), where mass spectrometry measurements are taken from samples from the University of California and Frisen's laboratory.
But if many of the “details” of our body are constantly 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 stay 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 agile 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 with time: mutations in mitochondria lead to a deterioration in the quality of its important composite material, collagen.
Y. FROLOV, “Science and Life” No. 7-2007 (based on the materials of the magazine “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!