Human digestive system chewing pieces of food into smaller and smaller pieces. This results in a much larger surface area for the action of digestive enzymes. The teeth are named after their particular roles in the process of mastication—incisors are used for cutting or biting off pieces of food; canines, are used for tearing, premolars and molars are used for chewing and grinding. Mastication of the food with the help of saliva and mucus results in the formation of a soft bolus which can then be swallowed to make its way down the upper gastrointestinal tract to the stomach. The digestive enzymes in
National Institute of Diabetes and Digestive and Kidney Diseases Diseases Data System; National Digestive Diseases Data System; Kidney and Urologic Diseases Research Centers; and Digestive Diseases Research Centers. June 10, 1993—The NIH Revitalization Act of 1993 (P.L. 103—43) established the NIDDK as the lead Institute in nutritional disorders and obesity, including the formation of a research and training centers program on nutritional disorders and obesity. The act also provided for the directors of the National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institute on Aging, National Institute of Dental Research, and the NIDDK to expand and intensify research and related programs concerning osteoporosis, Paget's disease, and related