It's a pretty common symbol, mostly in the U.S. How ever it is two snakes with a set of wings, this stands for medicine instead of the correct rod of asclepius. I hope in some way this helps.
Answer:
nausea and vomitting and blood in his stool
Answer:
The skin
Digestive tract
Vagina
Mucous membrane
Explanation:
The skin prevents microbes from entering the body
Digestive tract e.g. stomach acid is a natural defence mechanism
The vagina is acidic and this prevents harmful bacteria from growing with it's own flora.
Mucous membranes e.g. lining of the mouth, nose, eyelids are all defense mechanisms.