How we drink?

Can this problem make us think?

Why does liquid flow into my mouth? What entices it? And here is the reason: When drinking, we dilate the chest and thereby dilute the air in the mouth. Under the influence of outside air pressure, the liquid tends to run into the space with smaller pressure, and so it flows into our mouth.

The phenomenon here is similar to the phenomenon that will occur with liquids in connected vessels. If we dilute the air above a vessel, under the action of atmospheric pressure, the liquid will rise in that vessel. On the other hand, if you hold the lip tightly to the neck of a bottle, no matter how hard you try, you cannot 'drain' the water from the bottle into your mouth, because the air pressure in the mouth and on the water is the same.

So, strictly speaking, not only do we drink by mouth but also by the lungs, because the expansion of the lungs is the cause of fluid flowing into the mouth.