人解精品教学课件（中山大学）Lecture 9 digestive system Peritoneum.pptVIP

The principal function of the digestive system Ingestion—the taking of food into the mouth Mastication—chewing movements to pulverize food and mix it with saliva Deglutition—the swallowing of food to move it from the mouth to the pharynx and into the esophagus Digestion—the mechanical and chemical breakdown of food material to prepare it for absorption Absorption—the passage of molecules of food through the mucous membrane of the small intestine and into the blood or lymph for distribution to cells Peristalsis—rhythmic, wavelike intestinal contractions that move food through the gastrointestinal tract Defecation—the discharge of indigestible wastes, called feces, from the gastrointestinal tract The superficial structures of the oral cavity The oral cavity is formed by the cheeks, lips, hard palate and soft palate. The vestibule of the oral cavity is the depression between the cheeks and lips externally and the gums and teeth internally. The opening of the oral cavity is referred to as the oral orifice,and the opening between the oral cavity and the pharynx is called the fauces. The frenulum of the tongue When a short lingual frenulum restricts tongue movements, the person is said to be “tongue-tied.” If this developmental problem is severe, the infant may have difficulty suckling. Older children with this problem may have faulty speech. These functional problems can be easily corrected through surgery. Muscles of the tongue Extrinsic tongue muscles move the tongue from side to side and in and out. In hypoglossal nerve paralysis, the tongue is deviated to paralyzed side if the patient is asked to stick out his tongue as far as possible. Duodenum NaHCO3 :neutralizes chyme Digestive enzymes Contains Amylase: starch Trypsin: protein Lipase: fat Two nucleases: nucleic acid Pancreatic Juice A thick mucus blocks the pancreatic duct, and the patient must take supplemental pancreatic enzymes by mouth for proper digestion to occur. Cystic fibrosis The largest in