2023-05-21 00:13:17
Poikilothermic animals are said to be those that do not have chemical mechanisms to regulate their body temperature. An example is reptiles, who need the sun to get the necessary temperature for their metabolism to work properly.
At the other extreme are the so-called homeotherms, which maintain their body temperature within certain limits, regardless of the environmental temperature. Human beings are in this group.
Among the different mechanisms available to Homo sapiens to perform this function is sweating, with which we cool off when there is excess heat. For this, nature has endowed us with more than 2.5 million sweat glands, divided into two types: eccrine and apocrine.
The eccrine glands are located mainly on the palms of the hands and on the soles of the feet, while the apocrine glands are located mainly in the armpits, pubis, perineum and breast folds.
Pigs sweat, but little
One of our superpowers is undoubtedly sweat. We are the mammal that sweats the most: we cool ourselves by evaporating 1,000 grams of body fluid per hour and square meter of body surface. You could say that we are a living air conditioner.
And it is that despite the fact that we use the expression “sweat like a pig” these animals barely release 30 grams of body fluid for each 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 the “pig iron”, what 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 turned into liquid iron it was passed into molds reminiscent of a sow’s breasts, and when it was cold enough a layer of dew -sweat- was created on the plate. , the so-called «sweat pig».
sweat doesn’t smell
Sweat is a clear, salty liquid that is made up of 99% water, the rest being metabolic waste, sodium, chlorine, potassium and urea. In short, sweat does not smell like anything, although we would have no problem describing the smell of underarm sweat as rancid, sour, humid 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. In addition, the bacteria that inhabit our skin change with age, for this reason our body odor is not the same during childhood as it is in old age.
We know that different genera of bacteria inhabit 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.
In addition, Staphylococcus are capable of converting branched-chain aliphatic amino acids, such as leucine, into short-chain methyl-branched volatile fatty acids (isovaleric), which are responsible for that ‘acid point’ and characteristic of the smell of our armpits.
#armpit #sweat #smell #bad