For a long time, the number 37 trillion cells was cited as the generally accepted truth in popular science literature. This estimate dates back to a 2013 s…
For a long time, the number 37 trillion cells was cited as the generally accepted truth in popular science literature. This estimate dates back to a 2013 study in which scientists first attempted to count the cell types in the human body.
However, a large-scale study published in the journal PNAS has turned these ideas upside down. By analyzing data from more than 1,500 scientific publications, the researchers calculated the cell mass for people of different sexes, ages, and weights:
Adult man (70 kg): about 36 trillion cells;
Adult woman (60 kg): about 28 trillion cells;
10-year-old child (32 kg): about 17 trillion cells.
Which cells are the most numerous?
The human body contains over 200 major types of cells, which vary dramatically in size, shape, and function.
Red blood cells (erythrocytes): Transport oxygen and carbon dioxide. They make up the absolute majority of the total number of cells in our body.
Neurons: Transmit electrical and chemical signals, ensuring the functioning of the nervous system.
Muscle cells: Contract thanks to specialized proteins.
Beta cells in the pancreas: Produce the vital hormone insulin.
Platelets: Help blood clot, although formally they are not full-fledged cells, but fragments of larger bone marrow cells (megakaryocytes).
According to studies, blood cells are the absolute champion in reproduction – they make up nearly 90% of the daily cell renewal in the entire body.
Myth: “Every 7 years we get a completely new body”
The human body is not a static structure. Every day, nearly 330 billion cells die and are born in us. However, the rate of replacement depends entirely on the tissue:
The intestinal epithelium is renewed extremely quickly – the lining of the intestine is completely replaced every 5 days in order to withstand the aggressive environment of digestive enzymes.
Blood cells are also replaced at a rapid pace.
However, the brain and heart do not rejuvenate so easily. Many of the neurons in the brain accompany us throughout our lives, and the ability of the heart muscle to regenerate is very limited.
This is why the notion that every single atom and cell in us is replaced by a new one every seven years is a scientific myth.
What determines the number of cells in each person?
The final number varies for each individual and is influenced by height, weight, age and the ratio of muscle, fat and organs. A person who is 190 cm tall and weighs 90 kg logically has more cells than a person who is 160 cm tall and weighs 55 kg.
However, the relationship is not directly proportional, because the size of cells varies greatly. There is an interesting pattern in the human body: small cells (such as red blood cells) are present in astronomical quantities, while bulky and heavy cells are significantly fewer in number.
Bacteria in us: 10 times more or 1 to 1?
For a long time, it was believed that our microbiome contains 10 times more bacterial cells than our own human cells. However, more recent and precise calculations have refuted this exaggeration.
In 2016, scientists found that in a typical 70-kilogram person, there are about 38 trillion bacteria, and about 30–36 trillion human cells. This means that the ratio of human to bacterial cells in our body is actually practically 1:1.
Source: Rambler
The photo is illustrative: pexels-marek-piwnicki-3907296-11516492
