Deep inside, on a cellular scale, your body is in a state of constant activity to keep you alive. These processes include cell conversion, replacing the dying cells with new ones so you don’t cringe to pieces like a zombie.
New calculations reflect just how intense that process is. According to biologists Ron Sender and Ron Milo from the Weizmann Institute of Science in Israel, your body replaces about 330 billion cells every day. At that point, your body makes over 3.8 million new cells every second.
Most of these are blood cells, followed by cells in your gut. Everything else is less than 2 percent of your cell turnover. By confirming these numbers scientists could gain a better understanding of how the human body works and the role of cell turnover in health and disease.
It is a common myth that your body completely renews its cells every seven years. The reality is much more complicated. Some cells live only a few days, while others – such as neurons in the cerebellum and lipids in the lenses of your eyes – are limited only by the life of the host (you). So people are a long way from the Ship of Theseus situation.
However, although scientists have previously worked out estimates for how many cells there are in the body, what type they are, and what their life is, there is very little work to be done. was made to calculate the cell conversion rate.
This is what Sender and Milo have done now.
“Here we fill this knowledge gap in the dynamics of whole-cell transformation of the human body by examining the differences in life represented by different cell types and measurements. cell conversion rates in terms of both mass and number, “they wrote in their paper.
They based the calculation on a typical rower: a healthy male between the ages of 20 and 30, weighing 70 kilograms (154 pounds) and 170 centimeters (5 feet 7 inches) tall. Then, to estimate cell turnover rates, they included all cell types that make up more than 0.1 percent of the total number of cells.
Cell lifespans were collected from a literature review, using only those operations that directly measured human cell lifestyles. They then found the total cell mass for each type, based on the average cell size.
Based on this information, the pair then calculated that their cell reference rate would be around 80 grams (2.8 ounces) per day, or 330 billion cells.
Of that number, 86 percent would be blood cells, mostly erythrocytes (red blood cells, the most abundant cell type in the body) and neutrophils (the most abundant white blood cell type). Another 12 percent would be gastrointestinal epithelial cells, with very few skin cells (1.1 percent), endothelial cells that line the blood vessels, and lung cells (0.1 percent each).
While blood cells make up the majority of cell turnover in terms of individual cell count, by mass it is a different story. Only 48.6 percent of the mass is blood cells, of all kinds. Gastrointestinal cells make up another 41 percent. Skin cells make up 4 percent, and adipocytes, or fat cells, which are largely listed in cell numbers, make up another 4 percent by mass.
(If you ask what happens to the dead cells, they either grow more slowly, in terms of skin and gastrointestinal cells, and are sometimes reduced by parasites, or broken down and next partially circulated by the body. No rubbish, want not!)
It is important to remember that these figures tend to vary from person to person, depending on factors such as age, health, size and gender. But this work provides a baseline from which we can better understand how cell conversion works in the human body.
“There are many questions on the topic of organ renewal in health and disease that may be informed by our analysis,” the researchers wrote in their paper.
“For example, how does tumor cell turnover compare to the whole cell turnover of the patient’s body? What is the energetic and biosynthetic hole in tumor growth, and does it directly affect the allocation of resources, perhaps by exceeds resources dedicated to print renewal.? ”
These are important questions. Also, now you know – more or less – how much of your own material your body produces every day, like the miraculous machines we are: 3.8 million cells per second, one or two small eggs worth a day.
The research was published in Nature’s cure.