The best way is to just relax and try to act naturally. Just be calm and try to make it a bit funny to hide fear. :)
Appetite is not linked to hunger since appetite is the activity and drive in order to eat whereas hunger is the physical and mental state in which a person needs to eat.
Also appetite is linked to many unhealthy behaviors that can result to other symptoms of eating disorders which causes deletrious effects on one's mental and biological state.
The three main functions of the human digestive system are to break food down into chyme for the body's use, to secrete and absorb nutrients and bodily fluids into the gastrointestinal tract or the blood, and to store and eliminate waste. The digestive system has major parts and accessory parts.
what is this for, why do you need an answer?