Digestive_System

The Digestive Tract Lab with Oatmeal Cream Pies - Submitted by Holly Pate of Loudon High Materials needed: a large bowl, gloves for 5 students, spray bottles for remaining students in class (number varies; student doing esophagus does not need any supplies), a colander, 4-6 oatmeal cream pies (may also have one for each student to eat after completing lab). Teaching Notes: a. May add food coloring to water in spray bottles to make various digestive juices appear different and to add fun. b. Pancreatic juice may be in one bottle or split up between as many as 6 bottles, depending on number of students in class, so that each student gets to do some task. Students with spray bottles will squirt about 6 sprays of their digestive juice into the oatmeal mixture in the bowl. c. Students with gloves will massage the mixture and shape it. d. In large intestine, point out that the fluid drained from colander into bowl represents nutrients that were dissolved and absorbed in the small intestine and the water that is absorbed in the large intestine. Material left in colander represents fiber and waste that is not absorbed and passes through the digestive tract; discuss the need for cellulose to decrease risk of colon cancer. Oatmeal does contain cellulose. e. May use the digestive tract drawn on a shower curtain (art class may draw this for you) or drawn in sidewalk chalk on school parking lot. Make it large enough that the bowl can be passed along each portion, working its way through the alimentary canal. f. May write the info below on individual, numbered 3x5 cards and pass out to students to read as they carry out their assigned function. 1. Mouth a. Teeth: (gloves) I carry on mechanical digestion by breaking food into smaller pieces. b. Amylase: (spray bottle) I am secreted by serous cells in the salivary glands. I begin digestion by splitting starches and glycogen into disaccharides. c. Mucous: (spay bottle) I am secreted by mucous cells in the salivary glands. I bind food particles together and lubricate them for swallowing. d. Tongue: (gloves) I roll the mixture of food and saliva into a bolus for swallowing

2. Esophagus a. Peristalsis: I am the rhythmic contraction of muscles that ring the alimentary canal to propel food and digestive secretions down the esophagus and through the digestive tract. 3. Stomach a. Gastrin: (spray bottle) I am a hormone that increases secretions in the stomach. When you smell or taste good foods, or when food enters the stomach, the vagus nerve releases acetylcholine, which causes me to be secreted. b. Pepsinogen: (spray bottle) I am an inactive enzyme secreted by chief cells in the stomach. When I come in contact with hydrochloric acid, I change into pepsin. c. Pepsin: (spray bottle) I begin digestion of proteins by breaking them down into amino acids. d. Intrinsic factor: (spray bottle) I am secreted by parietal cells in the stomach. I am needed for Vitamin B12 to be absorbed in the small intestine ("Vitamin B12 for Healthy Blood Cells") e. Chyme: (gloves) I am the semifluid paste formed by mixing food and gastric secretions. f. Cholecystokinin: (spray bottle) I am a hormone that is released when chyme leaves the stomach and enters the small intestine. I decrease gastric motility as the small intestine fills with food. 4. Small Intestine a. Bile Salts: (spray bottle) I am the part of bile that emulsifies fats. I am made in the liver and stored in the gall bladder. Cholecystokinin stimulates my release into the duodenum when fats are present. b. Pancreatic Juice: (spray bottle) I travel through the pancreatic duct into the duodenum (first section of the small intestine. I contain: i. pancreatic amylase to split carbohydrates ii. pancreatic lipase to digest fats iii. nuclease to digest nucleic acids iv. trypsin to digest proteins v. chymotrypsin to digest proteins vi. carboxypeptidase to digest proteins c. Lactase: (spray bottle) I am secreted into the small intestine to break down lactose, or milk sugar. If you can’t make enough of me, you will be lactose intolerant 5. Large Intestine a. Main Function: (gloves and colander—squeeze fluid out of mixture) I absorb water and some electrolyes from the feces. Mass Movement: (gloves) Two to three times per day, I occur in the large intestine and lead to a defecation reflex.