Hormones and the nervous system coordinate digestion and absorption. The presence of food, or the thought or smell of food, can cause a positive response from these systems. Factors that can inhibit digestion include stress, cold foods, and bacteria.
After foods are digested and nutrients are absorbed, they are transported to specific places throughout the body. Water-soluble nutrients leave the GI tract in the blood and travel via the portal vein, first to the liver and then to the heart. Unlike the vascular system for water-soluble nutrients, the lymphatic system has no pump for fat-soluble nutrients; instead, these nutrients eventually enter the vascular system, though they bypass the activity of the liver at first. see also Bioavailability; Eating Habits; Insulin; Nutrition.
Insel, Paul; Turner, Elaine; and Ross, Don (2004). Nutrition, 2nd edition. Sudbury, MA: Jones and Bartlett.
Wardlaw, Kessel (2002). Perspectives in Nutrition, 5th edition. Boston: McGraw-Hill.
Whitney, E. N., and Rolfes, S. R. Understanding Nutrition, 9th edition. Belmont, CA: Wadsworth.
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