Verana E. Berrong, History of Tarrant County: From Its Beginnings until 1875 (M.A. thesis, Texas Christian University, 1938). Janet L. Schmelzer, Where the West Begins: Fort Worth and Tarrant County (Northridge, California: Windsor, 1985).
Page 4: Parasympathetic and sympathetic nerves innervate the GI tract. â¢ Both parasympathetic and sympathetic divisions of the autonomic nervous. system control digestion by contacting the enteric nervous system in the. wall of the digestive tract. â¢ The parasympathetic division typically stimulates digestion while the. sympathetic division typically inhibits it.
In general, the digestive system is set up to maximize absorption; there is no regulation of the amounts of substances absorbed into the body. A notable exception is iron, in which daily dietary absorption is regulated so that it matches daily iron loss. second signal depends upon the amount of iron in body stores. Iron absorption is stimulated if the level in body stores is low. These signals (and others) regulate iron absorption in the proximal duodenum, where iron is absorbed. An important player in this regulation is the recently discovered hormone hepcidin.