Yes. It's slightly more difficult because you're working against gravity, though. The oesophagus is a tube-like organ, and the act of swallowing squeezes the food through the tube to down to the stomach, or sideways, or up as the case may be.
While most animals have a difficult time swallowing their food when they are held upside down, there is one animal that cannot swallow when held in this manner. This animal is a chicken.
Yes
This would follow the same principal as swallowing when your upside down. Because humans swallow because of muscles in the pharynx and esophagus, not because of gravity, it must possible to choke when you are upside down.
It is difficult due to the apsence of gravity, so they will have to stand upside down to swallow fluid.
Chickens swallow differently than we do. We close our mouths and let our throats do the rest. Chickens open and close their mouths rapidly while tilting their heads up, they need gravity to do the rest.
just stay upside down as long as possible while in the air
You turn Upside down.
Peristalsis and esophgeal musclulature.
Peristalsis is the process that involuntarily makes it is possible to swallow water while standing on your head and moves food from your mouth down to your stomach. Peristalsis affects the muscles in the intestines also.
Peristalsis or muscles in your esophagus contract in a wave pushing the water to your stomach
Humans don't need gravity to swallow, although, interestingly, birds (i.e. canaries) do.
Gravity doesn't pull food down through your digestive system, but an array of muscles squeeze it through. This is also why you can swallow when upside-down.