There is such a bike on the Internet that a person is completely renewed in 7 years. Well, as if the cells of our body die and new ones are created, and the complete replacement of absolutely all cells in the body occurs in 7 years. That is, after this time you will be a completely new person.
And somehow recklessly I called it a bike. Here is a respected resource writes that according to scientists, the body replaces itself with a completely new set of cells every seven to ten years, and some of our most important parts of the body are renewed even faster.
However, in reality, everything is much more complicated …
To understand how the cellular composition of our body changes, it is first necessary to find out how cells arise. The body can create them in several different ways. First, existing cells can divide through a fairly simple process called mitosis. During mitosis, the parent cell splits into two new ones. These new cells, which are called daughter cells, are essentially copies of the mother cell.
The second way to create cells is from stem cells. These are special cells that are found throughout the body, albeit in small numbers. They can not only create their own copies through mitosis, but also synthesize new "specialized" cells. "Specialized" are blood cells and nerve cells that are unable to replicate themselves.
To control the growth of new cells, old ones must gradually die off. For example, the gaps between our fingers and toes are due in part to cell death at the time of our birth - this programmed cell death is necessary to keep our limbs from being webbed like some animals. After a while, all cells in the body wither and die.
However, not all cells have the same lifespan. For example, the cells lining the lining of our stomach can be renewed every two days because they are constantly in contact with acids involved in digestion. The cells that make up the skin change every two to three weeks. As the main defense against environmental influences, the skin must be in perfect shape at all times.
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Meanwhile, red blood cells, or erythrocytes, live for about four months. White blood cells, which are responsible for fighting infections, usually live for only a few days, a maximum of just over a week. At the same time, our fat cells live quite long - their cycle is 10 years on average. Bone tissue also regenerates for about ten years.
If someone thinks ten years is a long time, they just haven't seen anything yet. Other parts of the body are the same age as ourselves. For example, at birth, we receive one brain for life. Brain cells do not heal with age, although recent research suggests that cells in the hippocampus, which is responsible for memory, can grow back. Tooth enamel is also never restored, and we get pupils at one time for life.
Our body is made up of many different cells, each with its own function and life span. In the same way that we have to replace tires on a car more often than a transmission, some parts of our body need to be rebuilt more often than others. But even in spite of all these regenerative processes, none of us is given to become a completely new self. The fact is that some cells, as we already know, remain with us for life.
Igor Abramov