digestive system in children - 浙江大学.pdfVIP

Digestive system in children 浙江大学医学院附属儿童医院 江米足 Contents  Normal development, structure, and function of digestive system  Major symptoms and signs of digestive tract disorders in children  Common methods of examination for digestive system diseases in children Normal digestive tract phenomena  Gastrointestinal function varies with maturity  12 wk gestation: A fetus can swallow amniotic fluid  34 wk gestation: Nutritive sucking in neonates first  1 mo: show preferences for sweet and salty foods.  4 mo: Infants’ interest in solids increases.  The first few months of infants: coordinated oral and pharyngeal movements for swallowing solids  The current recommendation to begin solids at 6 mo of age is based on nutritional concepts rather than maturation of the swallowing process Esophagus  Hollow muscular tube, separated from the pharynx above and the stomach below by tonically closed sphincters.  To convey ingested material from the mouth to the stomach  No active role in digestion lacking digestive glands and enzymes  The length is 2.5 mm in 11 wk embryo, is 8- 10 cm at birth, and doubles during the first 2- 3 yr, reaching 25 cm in an adult. Stomach and intestines  The primitive gut is recognizable by the 4th wk of gestation and is composed of the foregut, midgut, and hindgut.  Foregut: esophagus, stomach, and duodenum  Midgut: small bowel and large bowel to the mid-transverse colon  Hindgut: the remainder of the colon and upper anal canal The structure of digestive tract  The wall of the stomach, small bowel, and colon consists of four layers:  mucosa  submucosa  muscularis  serosa Anatomy of Intestine Digestion and absorption  85% of the gastric mucosa is lined by oxyntic glands  contain cells that secrete h