As there is zero gravity in space, how do astronauts drink liquid from a container? Do they suck the liquid or is there any mechanism for that? Are there any changes in oesophagus?
swallowing of food or water from mouth to stomach is done with the help of peristalsis action of oesophagus
Then rhythmic, unidirectional waves of contractions will work to rapidly force the food into the stomach. This process works in one direction only and its sole purpose is to move food from the mouth into the stomach.
In earth it also happens but it is assisted with gravity but in space Peristalsis action is the only process by which food or water is taken to stomach .
As for the activity, Youtube videos are probably the best answer. Drinking is done usually through straws, but that isn't a strict necessity, just convenience. Foods that would produce a lot of crumbs are avoided, but generally eating and drinking isn't much of a problem.
As for oesophagus - lie on your stomach on a bed, with your head hanging down from it, and have a drink through the straw - not only the liquid isn't propelled to your stomach through gravity, just opposite, gravity pulls it in opposite direction, towards your mouth. Still, the pushing action of oesophagus will get it to the stomach just right.