Coming from the acid pH of the stomach which pH levels does the chime find when it enters the duodenum? Why is it necessary to maintain that pH level in the small intestine? What are the organs responsible for the pH level and how is it kept? After digestion the next step is absorption done by cells of the mucous membrane of the intestine. For this task a large absorption surface is an advantage. How is it possible in the small internal space of the body of a pluricellular organism to present a large intestinal surface?