[chris (OP)]

Delia West got in touch with me today to ask:

Why do we sweat around our eyes when we eat hot curry or chilli?

What does everyone think about this one?

[chris (OP)]

The spicy ingredient in chilli is a molecule called capsaicin. This engages with a specific receptor or docking protein called TRPV1, which is displayed on the surfaces of certain small calibre nerves known as C fibres. This convey pain and temperature sensation. When capsaicin binds it activates these nerves, fooling them into thinking that they are experiencing high temperature, which triggers the burning sensation.

These sensations are conveyed to the brainstem in the trigeminal nerve, which then presents the sensations to our consciousness by relaying the signals onto higher parts of the brain. One of the targets is the hypothalamus, which regulates body temperature. Although the signals in the mouth are spurious and you are not really overheating, the mouth says that the situation is heating up rapidly, so the hypothalamus engages the heat loss systems, which include diverting blood to the skin surface to radiate more heat energy and also making you sweat to cause heat loss by latent heat of evaporation.

Why we enjoy this experience I am unsure, but I am certainly a hot curry lover!

[mrsmith2211]

My scalp tends to sweat more than anything else.