How many cells does the human body have? This is a difficult question to answer. We can accurately count the number of bones (206 in an adult), teeth (32) or chromosomes (46). We can also approximately quantify the liters of blood, which fluctuate between 4.5 and 6. But the number of cells It is much more difficult to measure, since varies a lot more than blood.
Therefore, until now No very exact figures have been given.. Some estimates had been made, but very cursory. However, a team of scientists from the McGill Universityin Canada, has carried out a revision of studies that have allowed him to make a much more accurate measurement of the number of cells in the human body.
They have taken into account data for men, women and children, comparing the size of different cells and the tissues that contain them. This allows for a much closer calculation, since the larger the size of a cell, the smaller its quantity will be in the same tissue, and vice versa. With this mechanism, they have concluded that for a 70 kg man, a 60 kg woman and a 32 kg child, the number of cells is 36, 28 and 16 billion. That is, each of those numbers, followed by 12 zeros. It is a fairly high amount, of course, although we have to take into account some specifications.
How did they measure the number of cells in the human body?
This study is a bibliographic review. That is, its authors did not carry out any new research, but instead analyzed the existing data on the topic in the scientific literature.
In total, they took into account information from 1,500 documentswhich included information on 400 types of cellsin 60 different fabrics. Tissues are groups of these cells, which can be of very different sizes. As reported in Live Sciencecomparing the proportion between the smallest and largest cells that were analyzed with that between animals, could serve as an example the relationship between a shrew and a blue whale.
Thus, they saw that the inverse relationship between the number of cells in the tissues and their size was very regular. That is, as we have already seen, the larger they were, the less there were. And this was maintained with a similar proportion for most cell types. This allowed, together, to calculate how many cells there were in a tissue, knowing only the total size of the tissue and that of an individual cell.
There are many more studies on cell size and number in men than in women. Credit: Matheus Ferrero (Unsplash)
Details that we must take into account
Los gender bias They are everywhere, also in scientific studies. In fact, it’s the reason why, until recently, many drugs caused worse side effects in women. The clinical trials, in which the effects are analyzed and doses are calculated, were mostly carried out on men. Therefore, when these drugs were administered to women, the performance was very different.
Something similar happens with studies on cell number. Most of those that are taken into account the size of cells and tissues It has been realized in men. Therefore, these researchers have been able to make much more specific calculations for male adults than for women and children.
It is the first limitation of the research. But that is not all. There is also the fact that adipocytes and myocytes, which are fat and muscle cells respectively, vary greatly with a person’s build. It is true that we are talking about the order of billions; but even so, there can be large variations.
Even so, they are the most approximate data that has ever been obtained on the number of cells. Now, to be more specific, these scientists want to delve into how the number of lymphocytessince they are essential cells in the immune system, so they can also vary greatly, seriously affecting health, whether they fall or rise too high.
That will be the next step. Now, at least, we know with more accuracy, and with some gender bias, how many cells the human body has. It may not be accurate for a Trivial question, but it is interesting information.
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