Biology 20: Digestive System Did you get it? Questions and Answers Mouth 1. What is the purpose of chewing? a. break food into smaller pieces so there is a greater SA for chemicals to work on. 2. Salivary glands secrete a. saliva 3. Other than for digestion, what are two purposes of the salivary glands excretion? a. lubricates mouth to assist swallowing b. dissolves food, allows us to taste 4. What is the name of the enzyme in saliva and what nutrient does it digest? a. salivary amylase begins the breakdown of starch maltose-- glucose 5. What is the purpose of the tongue? a. moves food to the back of the mouth and to the teeth for chewing i. also helps with speech 6. What is the name of the lump of food that has been swallowed? a. bolus 7. What is the name of the process that keeps food moving through your esophagus even if you stand on your head? Describe how this process works. a. peristalsis: circular muscles in the esophagus contract behind the ball of food, pushing it forward. Longitudinal muscles in front of bolus contract 8. What is the name of the shared space in the throat for both air and food? a. pharynx (throat) 9. What keeps food from going down the larynx into the trachea? a. epiglottis it is a flap to cover the glottis (the opening to the trachea) 10. What is the name of the tube that reaches from the mouth to the stomach? a. esophagus Stomach 11. What is the name of the secretion that mixes with food when it reaches the stomach? a. gastric juice 12. Food mixed with the secretion from the previous question is given a new name:. a. chyme 13. What is the name of the muscular openings at either end of the stomach that operate like a drawstring? Give the specific name for each. a. esophageal sphincter/cardiac sphincter b. pyloric sphincter 14. What is the specific purpose of the esophageal sphincter and pyloric sphincter? a. esophageal sphincter/cardiac sphincter (stops chyme from going into esophagus) b. pyloric sphincter (controls exit into small intestine) 15. There are two chemicals that are secreted into the stomach. a. What is the name of the inactive enzyme that is secreted? i. pepsinogen b. The enzyme is secreted in its inactive form. What is the name of the active form of the enzyme? i. pepsin c. What specific substance activates the enzyme? i. HCl d. What nutrient does the enzyme digest? i. protein 16. There are two chemicals that are secreted into the stomach. a. What is the non-enzyme substance that is secreted into the stomach? i. gastric juice HCl, water, mucus, salts
b. What is the purpose of the non-enzyme secretion? i. HCl softens proteins and kills bacteria in food c. What keeps the non-enzyme secretion from destroying the cells lining the stomach? i. mucus is secreted with the HCl to protect the stomach ii. HCl is only secreted when food is in the stomach iii. pepsinogen is not active until HCl is present 17. Approximately what ph is the stomach environment? a. ph of 2 (range of 1-3) Small Intestine 18. Why is the small intestine named as such when it is actually longer than the large intestine? a. the diameter is much smaller 19. What is the name of the first part of the small intestine? a. duodenum 20. Why is food from the stomach not allowed in all at once? a. the small intestine does not expand like the stomach. It needs time to digest and absorb nutrients 21. When food enters the small intestine, a hormone is released. a. What is the name of the hormone? i. secretin and CCK b. Where does the hormone travel? i. from duodenum to stomach to inhibit stomach movements and secretions c. What is released as a result of the hormone traveling to its destination organ? i. CCK causes pancreatic secretions to increase more bile, more bicarbonate to increase the digestion of food 22. What is the name of the enzyme that breaks starch into disaccharides in the small intestine? a. pancreatic amylase 23. What is the name of the fat-digesting enzyme in the small intestine? a. lipase 24. What are the component parts that fat is broken into? a. glycerol and fatty acids 25. Bile is the name of the substance that helps with fat digestion but is not an enzyme. a. Where is bile made and where is it stored? i. it is made in the liver and stored in the gall bladder b. What does bile do if it is not an enzyme? Give the specific name of the process and also describe it. i. emulsification of fat breaks it into many smaller drops, so there is a much larger surface area of fat to digest 26. Why is it important for the small intestine to have such a large surface area? a. increases absorption of nutrients into the bloodstream 27. How is surface area maximized in the small intestine? Give the names of the structures. a. ridges, covered in villi. Villi are covered in microvilli. 28. Describe how each of the nutrients (carbohydrate, protein and lipids) enter the cells of the intestinal wall and finally the bloodstream. a. Carbs move by active trans into the villi and then into the bloodstream b. proteins move by active trans into the villi and then into the bloodstream c. fats: glycerol and fatty acids diffuse into the villi cells and then are coated in protein and diffuse into the lymph go to the chest and return to blood 29. If sugars are not immediately needed, they must be converted to and then they are stored in the and. a. glycogen, liver and muscles 30. How does one recognize the gall bladder? a. it is a small green sac
31. How does one recognize the liver? a. it is the largest interior organ and is dark brown 32. Where is the appendix located? a. between the small and large intestine (right hand side of body) 33. What is unique about the appendix? a. it is not necessary called a vestigial organ. It sometimes gets clogged and infected appendicitis and can rupture Hormonal Control (Table 6.4 p 230) 34. One hormone that acts in the digestive system is gastrin. a. What is the target organ of gastrin i. stomach b. What organ secretes gastrin? i. stomach c. What causes the release of gastrin? i. food enters the stomach and triggers stretch receptors d. What does gastrin do? i. causes the release of gastric juice and pepsinogen e. Describe the negative feedback loop for gastrin. i. food stimulates release of gastrin, gastrin causes the release of gastric juice containing water, mucous, salts and HCl. a lowered ph inhibits the release of gastrin. 35. Two other hormones that act in the digestive system are secretin and cholycystokinin (CCK) a. What causes the release of CCK and secretin? i. high fat food entering the small intestine stimulates CCK (and GIP). High acid food stimulates release of secretin b. What organ secretes CCK and secretin? i. duodenum c. What does secretin and CCK do? i. inhibit stomach movements and secretions allowing fatty foods to stay in the stomach longer than non-fatty ii. CCK: stimulates increased pancreatic secretions of digestive enzymes and gall bladder contractions (more bile to emulsify fats) iii. secretin: stimulates the pancreas to release more bicarbonate to neutralize acid d. Where do the hormones secretin and cholycystokenin work? i. they both act on the stomach (and pancreas) Large Intestine 36. What is another name for the large intestine? a. colon 37. What material is still absorbed from the chyme in the large intestine? a. water, vitamins, minerals, salts 38. Feces is made up of what? a. undigested material 39. The large intestine contains bacteria that are able to produce. a. vitamins from cellulose 40. When will a signal be sent to the brain for a bowel movement? a. when the rectum is full 41. Why is dietary fibre important? a. to make sure the large intestine gets cleaned out regularly 42. How are we able to consciously control exit of feces? a. the second sphincter is under conscious control
43. What is the name of the hole through which feces exit the body? a. anus Summary 44. In which organ did protein first begin to be digested? a. stomach 45. Why is it necessary that all protein-digesting enzymes travel to their destination in an inactive form? a. otherwise the human body itself would be digested 46. Starch began to be digested in which organ? a. mouth 47. Fat began to be digested in which organ? a. duodenum: small intestine Digestive organ Secretion Name Where secretion comes from Mouth 1.Saliva Salivary glands Components of the secretion (Make sure you list them all!!) Salivary amylase Water Mucus What it does Breaks down starch to disaccarides Lubricates mouth and throat, allows for taste Stomach 2. Gastric juice Cells lining the interior of the stomach Water Mucus Salts Hydrochloric acid Pepsinogen Softens food and kills bacteria Begins digestion of protein Small Intestine 3. Gastrin 4.Pancreatic fluid Cells lining stomach Pancreas gastrin Bicarbonate Trypsin and chymotripsin Pancreatic amylase (carbohydrase) Lipase Causes secretion of pepsin and gastric juice Neutralizes acidic chyme Digests protein Digests starches Digests fats 5. bile 6. Hormones Liver, stored in gall bladder CCK Secretin Bile (bile pigmenst and bile salts) Suspends fat in water, using bile salts, cholesterol and lecithin to aid digestions of fats in small intestine Decreases stomach movements and secretions -causes release of pancreatic enzymes and bile -causes release of bicarbonate
Large Intestine State here what is absorbed in the colon and what is contained in the feces. Water, salts, vitamins absorbed from colon Undigested material is left in the feces.