Nutrition Science and Everyday Application - beta v 0.1

150 ALICE CALLAHAN, PHD, HEATHER LEONARD, MED, RDN, AND TAMBERLY POWELL, MS, RDN
except that accomplished by the bacteria that inhabit this portion of the GI tract. There
are trillions of bacteria residing in the large intestine (referred to as the bacterial flora),
exceeding the total number of cells in the human body. This may seem rather unpleasant,
but the great majority of bacteria in the large intestine are harmless and many are even
beneficial—facilitating chemical digestion and absorption, improving immune function, and
synthesizing vitamins such as biotin, pantothenic acid, and vitamin K.
The figure below summarizes the functions of the digestive organs.
Figure 3.14. Summary of digestion and absorption. Digestion begins in the mouth and continues
as food travels through the small intestine. Most absorption occurs in the small intestine.