Question

How is food taken inside our body when we stand upside down

Answer 1

Dear student,

The food is actually pushed toward the stomach through the esophagus, an approximately 25 cm long (in adults) muscular tube leading to the stomach.
The esophagus is lined with smooth muscle, a type of muscle that contracts involuntarily (without us making it contract).

Food and water entering the esophagus does not drop down and fall into the stomach; instead it is pushed through by waves of contractions (squeezes) from the bands of muscles that encircle the esophagus (of course, gravity does help a little bit).

These contractions are known as peristalsis ("pear-ih-stall-sis"). Once food or water reaches the end of the esophagus, a muscle which acts as a valve called sphincter ("sfink-tur") closes so it can't come back up! Peristalsis is so strong that it can actually enable a person to swallow food or water while upside down!

Regards