How cold feet are linked to colds
In a study, 13 out of 90 students developed a cold within 5 days after holding their feet in a basin of cold water (+ 10 ° C) for 20 minutes. At the same time, only 5 out of 90 students fell ill in the control group. Here, many will remember the meme about “British scientists” who regularly entertain with their eccentric experiments. However, in addition to the statistical relationship between cold feet and colds, there are studies that reveal the mechanism of this phenomenon.
It is well known that in the cold skin capillaries narrow, redistributing about a liter of blood deep into the body. This fundamental reflex reduces heat transfer and stabilizes overall body temperature. Moreover, local cooling of an individual part of the body also has a systemic effect.
Back in 1919, it was found that cooling of the skin causes a reflex of vasoconstriction in the nasal cavity. As a result, the secretion of nasal mucus, which serves as the first barrier to infection, is significantly reduced – about 10% of inhaled microorganisms “stick” to it and are bound by antibodies. The remaining 90% are carried by the inhaled air into the bronchi and even reach the alveoli, but we will return to their fate later.
However, what does the cooling of the legs have to do with – you ask – if cooling of any part of the body surface causes contraction of the capillaries of the nasal mucosa. For example, hands very often freeze, but this does not end with a cold. The answer to this question may be hidden in the fact that it was students who fell ill with colds who felt general hypothermia while keeping their feet in cold water. Since a very large volume of blood passes through the legs, then for 20 minutes of passive sitting over the basin, heat loss could well cause general hypothermia. What happens in the nose in this case?
Both with general hypothermia and with local cooling of the nasal mucosa, the ciliated epithelium stops moving and evacuates the secreted nasal mucus into the nasopharynx. Under the influence of gravity, stagnant mucus finds its way out in the form of familiar snot. Meanwhile, normally, swallowing nasal mucus plays an important role in preventing infections of the ENT organs.
Thus, the contraction of the capillaries in the nasal mucosa during cooling of the skin (including the skin of the legs) is not enough to cause a cold. The cooling of the legs in the experiment caused general hypothermia in the most “frozen” students, as a result of which the mechanism of recognition of infection by the mucosal immune system of the intestine was blocked. But the reduction in mucus secretion in conjunction with the termination of its evacuation into the intestine may well end in a coldПоділитися цим: