Rhythms of renewal of the human body
Aging is inevitable and does not please anyone. Not only women, but also men are increasingly interested in rejuvenating cosmetics and procedures that make it possible to hide their true age. Not understanding that artificially stretched skin will not help to lose a decade. In this case, rejuvenation is inherent in us mother nature, and all you need is to stick to a healthy lifestyle, so as not to violate the natural processes of organ renewal.
Has it ever happened to you - you decided to lead a healthy lifestyle: abandoned bad habits, began to regularly do exercises, eat well, use natural cosmetics, but a week passes, followed by a second, and the visible result (the hair did not become healthy and silky, nails all also break down, pimples do not disappear) and internal calmness is not observed?
It is known that cells in our body are being updated. But how is the body cell renewal? And if the cells are constantly updated, then why does old age come, and does not last forever youth? And then, succumbing to the frustration ("Nothing will help me"), my hands drop, and I want to return to the old one, hoping for "miraculous" pills and plastic surgery ("They'll bring the body into tone!").
The brain is 20 years old
The brain is the most important and one of the most vulnerable organs in our body. And he begins to grow old before everyone. 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 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 synapses. It ensures the transfer of information from one cell to another, and reducing 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 be left with the information that was contained in them-our thoughts, emotions, memories, skills, experience. Wrong way of life - smoking drugs, alcohol - all this to some extent 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 assimilate new information, then to 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 useful flora, which can be disturbed by both malnutrition and simply over time. The number of beneficial bacteria begins to rapidly decline 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 that over time, the female breast reduces the amount of fat tissue, the skin loses its elasticity, and the breasts begin, as they say, to sag. But it is much more terrible that with age, tissue cells can mutate and turn into cancerous, so after 35 women it is better to visit the mammogram more often.
Bladder - 65 years
Aging of this organ threatens you with inconvenience caused by constant "urges", and, possibly, even incontinence. Particularly receptive to these problems are women: they have a bladder volume by the age of 70 reduced by half compared to, for example, from the 35th, and even the muscles in the groin lose their tone. As a result, a woman has to visit the "ladies' room" almost every 20 minutes, but the bladder is not completely emptied, and this greatly increases the risk of developing an infection.
Heart - 40 years old
The fact that the heart cells also have the ability to update, it became known more recently. According to researchers, this happens only once or twice in a lifetime, therefore it is extremely important to preserve 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, the patency of the arteries is reduced by cholesterol plaques, the risk of ear infarct increases at times every year.
Lungs - 20 years
From this time, the volume of your lungs begins to decrease gradually. In addition, the entire muscular system that controls our breathing is gradually weakening, and as a result, by the age of 40 some unhappy people are literally choking. By the 70th volume of air that we can breathe at a time, it's about halved compared to the 30s.
For each type of lung tissue, cell renewal occurs at different rates. For example, air sacs that are located at the ends of the bronchi (alveoli) - are revived every 11 to 12 months. But the cells 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 the renewal of the alveoli, destroy them and in the worst case can lead to emphysema.
Liver - 70 years old
This is perhaps the most age-stubborn organ in the whole human body. His cells have an amazing ability to recover quickly and at low cost, so the whole body can literally grow from one fragment in a few months. Using this magic property, transplant doctors often take organs of 70-year-old donors to treat much younger patients.
The liver is the champion of regeneration among the organs of the human body. Liver cells are updated approximately every 150 days, that is, the liver is "born" anew once in five months. She is able to recover completely, even if as a result of surgery a person has lost up to two thirds of the body. 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 complicated by alcohol and most of the drugs. And if this body is not paid attention, it will cruelly take revenge on its owner terrible diseases - cirrhosis or cancer. (By the way, if you stop drinking alcohol for eight weeks, the liver is able to completely clear).
The walls of the intestine from the inside are covered with tiny villi that provide absorption of nutrients. But they are under the constant influence of gastric juice, which dissolves food, so they do not live long. The terms of their renewal are three to five days.
Skeleton - 35 years old
Throughout our life, the cells of our bones are gradually being updated. In children, this process takes a couple of years, for adults and the elderly can stretch out to dozens. The rate of renewal begins to fall 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 growth.
The bones of the skeleton are updated continuously, that is, at each moment of time in the same bone there are both old and new cells. The complete renewal of the skeleton takes about ten years. This process slows down with age, when the bones become thinner and brittle.
Kidney - 50 years old
In 50 years, tissues that serve as a kind of 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 falls by half. In fact, this leads to urinary incontinence and pain when urinating.
Prostate - 50 years old
The prostate does not contract with time, but, on the contrary, it grows, absorbing more and more testosterone hormone. The normal size of this body is about with a walnut, with age it can increase to an orange. This leads again to problems with urination, which, according to statistics, are harassed by about half of all men over the age of 50. At the same time, 40-year-olds like this are almost unfamiliar.
Teeth - 40 years old
The salivary glands work worse and worse, the saliva is unable to wash off 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 exercise, you have a chance to check on yourself how the condition of your muscles changes after 30. It becomes more difficult to exercise, and the relief does not appear after a couple of weeks of lessons from case to case. 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 exercises will help you to avoid this.
Sexual system - 35 years
In women, the productivity of the genital organs begins to fall after 35, and with it the chances of becoming pregnant decrease. From the same age, the quality of male sperm deteriorates, so the risk of miscarriage is significantly higher among women who conceived with a man after the age of 35.
Hair - 30 years
Hair grows an average of one centimeter per month, but the 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. The hair of the eyebrows and eyelashes grow in six to eight weeks.
Human hair can grow for 3 years, after which it falls out, giving way 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 contract, the hair becomes thinner and eventually stops growing. As for gray hair, it appears due to a reduction 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 the corneal cells are renewable. There is a replacement of its top layer every 7 - 10 days. If the cornea is damaged, the process is even faster - it can recover overnight.
For most 40-year-olds, glasses or lenses are common. The most common ailment that overtakes our eyes in old age is hyperopia, 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 language have a rather short life cycle - ten days.
Smoking and mouth infections weaken and inhibit this ability, and also reduce the sensitivity of the taste buds.
Leather - 20 years
The superficial layer of the skin is renewed every two to four weeks. But only in the event that the skin is provided with proper care and it does not get excess ultraviolet. Negative effects on the skin are also smoking - this harmful habit for two to four years accelerates the aging of the skin.
Skin aging is explained by the reduction in the release of collagen and elastin, substances that maintain the elasticity of the skin and help it to recover from injuries and stretch marks. In addition, the skin itself is updated much more slowly, changes color, it becomes thinner. Speeding up this process can be smoked and constant direct exposure to the sun.
The most famous example of an organ renewal is the nails. They grow 3 to 4 mm every month. But it's on your hands, your toes grow two times slower on your feet. Completely the fingernail on a finger of a hand is updated on the average for six months, on a toe - for ten.
And, on the little fingers, the nails grow much slower than the rest, and the reason for this is still a mystery to the physicians.
Voice - 65 years old
With age, the voice becomes quieter, a hoarse voice appears. This is explained by the fact that the soft tissues of the larynx lose elasticity and tone. As a result, a woman can find that she began to talk almost bass, and the man, on the contrary, will begin to "sound" a little higher than before.
Hearing - 55 years
According to statistics, almost half of people older than 60 have serious hearing problems and even suffer from deafness. The reason is 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 buds in the tongue is about 10,000. By the time of old age, it is about halved. So it is with the sense of smell.
How many years have you felt inside?
Not on the passport, but on the internal sensations? Many of my friends say that they are 18-25 years old (they have more than 50 by their passport). One of my friends (let's call her Lyuda) - bioenergetic, always says that she feels 15 years old!
And I was very surprised to read that the Swedish neurologist Jonas Frisen had established: for every adult, an average of fifteen and a half years! So Luda just perfectly knows and feels her body!
In the literature, I very often meet the claim that our body is almost completely renewed every seven years. Old cells gradually die off, and new cells appear in their place. But where did this magical figure "seven" come from, I can not understand.
For some cells of our body, the renewal time can be set more or less accurately, namely: 150 days for blood cells, after a gradual replacement of which they observe after blood transfusion, and also 14 days for skin cells. Skin cells originate in its deep layers, gradually come to the surface, where they die and peel off.
On a human, it is difficult to carry out experiments to determine the life span of cells, so try, as always, in rats and mice. To do this, they are given with food or injected with special radioactive additives - labeled nucleotides, which are building blocks of DNA.
New cells, not suspecting anything, build these tags into their structure. The number of labeled cells in different organs or tissues of the body can be measured and calculated the proportion of those new cells that were born during the time that passed after the mouse received radioactive DNA.
You can not apply this method to a person. Some researchers have attempted to determine the age of human cells along the length of telomeres (these are the final regions of chromosomes). But this method did not give reliable results, as some cells began to "grow" telomeres after division.
Finally, the Swedish researcher Jonas Frisen decided to use the method of archaeologists and historians, who determine the age of subjects containing organic matter, according to the isotope carbon-14 (14C). I will not bore you with the theory (although it is very interesting), but this method failed miserably, since it works reliably only for long periods of time, since the concentration of this isotope is very low.
But Fryshena was inspired by the idea that from 1955 to 1963, because of nuclear weapon tests, the concentration of the 14C isotope in the air increased and was twice the norm. Over time, it decreases and now has returned to the usual indicators. Frisen believed that his method allows you to determine the age of any cell born between 1955 and 1990.
Frisen in 2005 published preliminary results of his research. He confirmed that the cells that are in direct contact with the external environment-and these are epidermal cells of the skin-live for two weeks, as I wrote before, and the intestinal epithelium cells that regularly interact with food live only 5 days.
Erythrocytes, or red blood cells, have a life span of 150 days (according to Frisen).
But if many "details" of our body are constantly updated and as a result are much younger than the owner, some questions arise.
For example, why does the skin not remain lifelong smooth and pink, like an infant, if the top layer of the skin is always two weeks old?
If the muscles are about 15 years old, then why is a woman at 60 not as flexible and agile as a 15-year-old girl?
Answers to these questions Frisen saw in the DNA in the mitochondria (this is part of every cell). It quickly accumulates various damages. That is why the skin grows old with time: mutations in the mitochondria lead to a deterioration in the quality of such an important composite skin material, like collagen.
According to many psychologists, aging is due to those mental programs that are inherent in us since childhood. But this will be discussed in more detail in other articles.
Here we will consider the terms of updating specific organs and tissues, which are shown in the figures. Although there everything is written in such detail that there can be this commenting unnecessarily.
How old are you?
Do not rush to answer this simple question, as it seems, because the Swedish neurologist Jonas Frisen answered for you: for each adult, an average of fifteen and a half years. If your passport, for example, sixty, the lens of your eyes is on average 22 weeks older (!), The brain is about your age, but your skin is only two weeks old.
From one popular science book to another roams the assertion: our body is almost completely renewed in seven years. Old cells gradually die, their places are occupied by new ones.
The cells are really updated, but where does the mythical figure "seven" come from, nobody really knows. 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 a blood transfusion, and two weeks for the skin cells that appear in its deep layers gradually migrate to the surface, die off and exfoliate.
Experiments to measure the lifespan of cells have been conducted for about half a century, but only in rats and mice. Animals are injected intravenously or labeled (radiolabeled) nucleotides in the food - building blocks of DNA. New cells embed these tags in their genetic material. Their number in different tissues and organs can be measured and the proportion of cells that were born in the time elapsed after the introduction of radioactive DNA was calculated.
Of course, this method is inapplicable to man. We tried to determine the age of human cells along the length of telomeres - the terminal regions of chromosomes. Telomeres are shortened with each cell division. But to develop on this basis a reliable method for determining the age of the cell failed, especially as some cells, as it turned out, are able to "grow" telomeres after division.
The Swedish researcher Jonas Frisen decided to use the method of archaeologists and historians, who know how to determine the age of subjects containing organic matter, by carbon-14 (14C). This rare and slightly radioactive isotope of carbon is constantly formed in the stratosphere, where cosmic rays knock out one proton from the nuclei of nitrogen atoms. Gradually (half-life 5730 years) 14C again turns into nitrogen. Plants in the process of photosynthesis absorb from the atmosphere 14C and build it into sugar molecules. Animals eat plants, and therefore all living things contain a little of this isotope. Approximately one of the trillions of carbon atoms in your body is carbon-14 at the site of ordinary carbon-12. When the body dies, it ceases to receive a new 14C, and the one that has accumulated during the lifetime, gradually disintegrates. This decay, going with a certain speed, and allows you to determine how long the living matter has become dead. For example, when a tree was cut from which a prehistoric boat was made, or when a calf was killed to make a parchment for the manuscript from its hide. However, because of the extremely small amounts of the isotope and the slow rate of its decay, the method is suitable only for large time intervals.
But here, as they say, there would be no happiness, but misfortune helped. Frisen realized that to determine the age of individual cells, one can use that not very short period of time when, due to human activity, the amount of 14C in the atmosphere has greatly increased. From 1955 to 1963, nuclear weapons tests brought large amounts of the 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 was measured many times and continues to be measured in various parts of the Earth, so that a curve of sharp growth and a gradual fall of this magnitude is compiled. 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 World Ocean. But Frisen believes that his method allows you to determine the age of any cell born between 1955 and 1990.
How dangerous is the decay of radioactive carbon in the body? In a human body weighing 75 kilograms, about 300 trillion trillion (3 × 1026) of carbon atoms, of which only 350 trillion (3.5 × 1014) are carbon 14C. Except for the mineral component (mostly bones) and assume that the rest of the body tissues are 14C distributed evenly, then in each cell, on the average, only 11 14C atoms. DNA by weight is about 1% of the cells. The isotope 14C decomposes so rarely that if we take a separate cell chosen at random, then in its DNA, one 14C atom will decay once every 18,000 years (we take exactly the 14C that enters the DNA, since changes in the composition of this molecule can be important for health of the organism and its offspring). If you think that you will live 70 years, the chances that a particular individual cell of your body will ever experience an "atomic explosion" of one carbon atom in your DNA is 1 to 260.
At its appearance, the cell receives a set of chromosomes, which remain with her throughout her 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. The analyzes are carried out by atomic mass spectrometry.
In 2005, Frisen and his collaborators published preliminary results of cell analysis of people living in the 14C peak. As would be expected, the life span of cells directly in contact with the external environment, the epidermal cells of the skin (two weeks, as we mentioned), and the cells of the intestinal epithelium, which are constantly abraded by the passing food masses (5 days), are the shortest of all. Red blood cells, according to Friesen, live 150 days. Muscle cells of intercostal muscles in people 37-40 years old, as it turned out, on average, are 15.1 years old, and intestinal cells (except epithelium) - 15.9 years.
Friesen as a neurologist is, of course, most interested in the brain. Of animal studies, as well as one patient dying of cancer and agreeing to introduce a weakly radioactive isotope into the brain, it is known that after birth new neurons arise only in two areas - in the hippocampus and around the ventricles of the brain.
While the new method measured the age of only a few areas of the brain. According to Friesen, the cells of the cerebellum are younger than the person on average by 2.9 years. 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 the cerebellum is finally formed about three years. The cerebral cortex has the same age as the human being itself, that is, during the course of life, new neurons do not appear in it. The rest of the brain is still being studied.
The measurement of the age of individual tissues and organs is not carried out out of curiosity. Knowing the speed of turnover of cells, we may learn 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 medications for depression stimulate this process. Alzheimer's disease is also associated with inadequate neurogenesis in the hippocampus. With Parkinson's disease, as far as we know, the dying out of old cells is not balanced by the appearance of new ones.
Knowing how often new people develop new fat cells will help to treat obesity. While no one knows if this disease is associated with an increase in the number or size of fat cells. Knowing the frequency of the appearance of new cells of the liver and pancreas will create new methods for diagnosis and treatment of liver cancer and diabetes.
The question of the age of the heart muscle cells is very relevant. Experts believe that dying cells are replaced by a fibrous connective tissue, so the heart muscle weakens with time. But there is no exact data. Frisen 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 on the sixth week of embryo life and remains for life. But on 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 cataract for five years, says Bruce Buchholz from the Livermore National Laboratory (USA), where mass spectrometric measurements of samples supplied from the University of California and Friesen's laboratory are carried out.
But if many "details" of our body are constantly updated and as a result are much younger than the owner, some questions arise. For example, if the top layer of the skin is only two weeks old, why does not it remain lifelike 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 the mitochondrial DNA. It accumulates damage faster than the DNA of the cell nucleus. That is why the skin eventually grows old: mutations in the mitochondria lead to a deterioration in the quality of its important composite material, collagen.
Yu. 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 are aware of what affects the renewal of cells in the body? Draw conclusions! All of you good! Comment and write your observations and conclusions!