It is said that poikilothermic animals are those that do not have chemical mechanisms to regulate their body temperature. An example is reptiles, which need the sun to achieve the necessary temperature for their metabolism to function correctly. At the other extreme are the so-called homeotherms, which maintain their body temperature within limits, regardless of the environmental temperature. Human beings are in this group. Among the different mechanisms that Homo sapiens have to perform this function is sweating, with which we cool off when there is excess heat. For this, nature has provided us with more than 2.5 million sweat glands, divided into two types: eccrine and apocrine. The eccrine glands are mainly located in the palms of the hands and the soles of the feet, while the apocrine glands are located mainly in the armpits, pubes, perineum and folds of the breasts. Pigs sweat, but little. One of our superpowers is, without a doubt, sweat. We are the mammal that sweats the most: we cool ourselves by evaporating 1,000 grams of body fluid per hour per square meter of body surface. You could say that we are a living air conditioner. And despite the fact that we use the expression "sweat like a pig," these animals barely release 30 grams of body fluid for every square meter of their anatomy. It seems that the origin of the expression is Anglo-Saxon, it is a literal translation of "sweating like a pig", but the pig they refer to is not the animal, but rather the "pig iron", which we know in Spanish as pig iron, the product resulting from the smelting of iron in a blast furnace. The English gave it the name "pig iron" because when it was converted into liquid iron it was passed into molds that resembled the breasts of a sow, and when it was cold enough a layer of dew - sweat - was created on the plate. , the so-called “sweat pig”. Sweat does not smell Sweat is a clear, salty liquid that is composed of water, the rest is metabolic waste, sodium, chlorine, potassium and urea. In short, sweat does not smell like anything, even though we would have no problem describing the smell of armpit sweat as rancid, sour, damp and bitter. What causes the bad smell of sweat, which in scientific terms is called bromhidrosis, is the microbiota, the endogenous flora of the skin, which is different depending on the area of the skin that we want to study. It is precisely this peculiarity that explains why body odor is not the same throughout our anatomy. Furthermore, the bacteria that inhabit our skin change with age, which is why our body odor is not the same during childhood as it is in old age. We know that different types of bacteria live in our armpits, among which Staphylococcus, Cutibacterium and Corynebacterium stand out. All of them are capable of fermenting glycerol and lactic acid into short-chain volatile fatty acids (C2-C5), which are the molecules that cause bad armpit odor. MORE INFORMATION news No 'Champion', a new dinosaur the size of a city bus, discovered in Castellón news Yes The million-dollar business of laboratory monkeys In addition, Staphylococcus are capable of converting branched aliphatic amino acids, such as leucine, into volatile branched fatty acids with short chain methyl (isovaleric), which are responsible for that 'acid point' and characteristic of the odor of our armpits. ABOUT THE AUTHOR Pedro Gargantilla is an internist at the El Escorial Hospital (Madrid) and author of several popular books.
