Because the food travels though it
I believe it is viral, they can not be treated with antibiotics but can be prevents with vaccines.
I will state the categories and each corresponding statement to make all the ideas already mentioned clearer.
Let´s start by defining Anabolic as "The processes that build up new complex substances from simple molecules" and Catabolic as "the processes that break down complex substances into simpler ones"
ANABOLIC: Building bones, increase in muscle mass.
CATABOLIC: Jogging, breakdown of complex carbohydrates into simple sugars, post-lunch nap, digestion.
