Biology 12: Digestion Review Story 1

Transcription

1 Biology 12: Digestion Review Story 1 Review Questions: 1. Define digestion. Why is this process important? 2. List the 4 functions of the digestive system. 3. How does saliva contribute to the formation of a bolus? 4. What prevents food form entering the nasal chamber and the trachea during swallowing of food? 5. The opening to the larynx is called the glottis, which is covered when the trachea moves up by the epiglottis. 6. What is responsible for heartburn and how is it normally prevented from occurring? 7. List the functions of the stomach. What is chyme? 8. What is the function of the gastric glands in the stomach? 9. What is an ulcer an why does it form? 10. List 4 functions of the small intestine. What molecule from the pancreas neutralizes the acidity of chyme? 11. Describe the structure of villi and microvilli in the small intestine. 12. How are the small nutrient molecules absorbed across the wall of each villus? What do they enter? 13. What is the function of the large intestine? How does its size compare with the small intestine? 14. Which organ of the large intestine may play a role in immunity and if inflamed leads to appendicitis? 15. Over 99% of the colon bacteria are E.coli (obligate anaerobes), bacteria that die in the presence of oxygen. 16. Describe the effects of bacteria in the large intestine. What does a high chloriform count in swimming water mean? 17. Why will food poisoning and nerve stimulation cause diarrhea? 18. How does mil of magnesia and mineral oil work to overcome constipation? 19. What is the exocrine function of the pancreas? How does its products get to the duodenum? 20. Name the 2 hormones secreted from the duodenal wall that signal the pancreas and the gallbladder to release their products. 21. What are the components of bile? Give their function. What organ produces bile? Where is it stored? 22. Explain why the liver is said to act as the gatekeeper to the blood. 23. Define deamination. What happens to those amino groups in the liver? How is urea excreted? 24. List the 6 (7?) functions of the liver. 25. Name the enzyme found in the stomach. What is it formed from? What does it act upon? What products will it form? Questions: 1. Name the Pancreatic enzyme that in the duodenum will: a. digest starch: amylase It forms the product maltose b. digest Protein: trypsin It forms the product peptides c. digest fat droplets: lipase It forms the product fatty acids + glycerol d. The end products of fat digestion reform in the epithelial cells and are

2 Biology 12: Digestion Review Story 2 attached to phospholipids, cholesterol and protein to form a temporary fat carrier molecule called a chylomicron. These carrier molecules are then dumped into the lacteal (part of the lymphatic system system) and will enter the blood-stream with the rest of the lymph at the left subclavian vein. They will be picked up eventually by the liver which will convert them to a lipoprotein The bad lipoproteins are called low density lipoproteins (LDL ) And the good lipoproteins are called High Density lipoproteins (HDL ). When your body has too much energy, or saturated fat, the liver tends to put fats into the LDL s. When the body needs the energy from the fat, the liver tends to send it to the cells in HDL s. LDL s are associated with atherosclerosis (clogging of the arteries). 2. The 2 enzymes produced by the epithelial cells to complete the digestion of peptides and maltose are peptidases and maltase The end products that are formed from these degradations are amino acids and glucose. 3. Lactose intolerance is due to inability to digest milk - usually a lack of lactase. The consequence of drinking milk for these individuals is the sugar lactose is used by the bacteria in the gut as a food source - they produce flatulus- causes cramping, irritation, diarrhea, etc 4. The stomach is directly connected to the esphagus above and the duodenum below. 5. The major food digested in the stomach is Protein, which is hydrolyzed by the enzyme Pepsin.

3 Biology 12: Digestion Review Story 3 6. Among its chemical aspects, every digestive enzyme has a preferred ph and temp. 7. Before fats are digested by the enzyme lipase, they are first emulsified by bile. 8. Pancreatic juices enter the small intestine by way of the pancreatic duct food. duct and contain enzymes for the digestion of every type of 9. The liver first receives the products of digestion by means of the hepatic portal vein; any excess glucose is stored as glycogen (in the liver) 10. The secretion of digestive juices is controlled in general by gastrin, CCK and secretin. (page 208 in text) 11. Surface area in the small intestine is increased greatly by the presence of folds and villi and microvilli. 12. Complete the following table: Hormone Where Cause of Affects What Affected Organ Produced Release Organ? Releases a. gastrin Stomach Meal high in protein Stomach HCl and pepsinogen b. secretin Cells of Acid in Pancreas and Bile, Pancreatic duodenal wall duodenum liver juices c. CCK Cells of Part. digested Pancreas and Bile, pancreatic

4 Biology 12: Digestion Review Story 4 duodenal wall fat or protein liver juices 13. List 6 functions of the Liver detoxifies blood **** stores iron and fat soluble vitamins (I missed this one in the notes) makes blood proteins makes lipoproteins maintains blood glucose levels produces urea from breaking down amino acids converts Hb from RBCs into billirubin and biliverdin produces bile 14. Vitamins are often portions of coenzymes, necessary for cellular metabolism. a. In which part of the digestive tract are nutrient molecules absorbed? S.intestines b. The absorbed nutrient molecules enter what vein associated with the intestine? Hepatic portal vein c. In which part of the digestive tract does pancreatic juice enter? duodenum d. In which part of the digestive tract does bile enter? duodenum e. What parts of the digestive tract do not actually contain food and might be called accessory organs of digestion? Salivary glands, pancreas, liver, gallbladder f. What parts of the digestive tract do not have ducts entering them and do not secrete digestive juices? Esophagus, large intestine, rectum, anus

5 Biology 12: Digestion Review Story 5 Digestion of Carbohydrate (starch) Starch digestion begins in the mouth. Here the ducts empty from the salivary glands. The salivary juice contains the enzyme amylase and this enzyme breaks down starch to the disaccharide maltose. Starch is also acted on in the duodenum. Here, a duct empties from the pancreas Pancreatic juice contains the enzyme amylase which breaks down starch to the disaccharide maltose. Starch digestion is complete when this disaccharide is broken down to glucose, a monosaccharide, which can be absorbed by intestinal villi. The enzyme that converts maltose to glucose is called maltase epithelial cells of the intestinal villus. and this enzyme is secreted by 17. Digestion of Protein (meat) Protein digestion begins in the stomach. The gastric Glands line the wall of the stomach. They secrete the enzyme pepsinogen (pepsin) which breaks down protein to peptides. Another enzyme called trypsin is secreted by the pancreas and this enzyme acts on protein in the duodenum, also breaking down protein to peptides. Protein digestion is complete when peptides are broken down to amino acids, molecules small enough to be absorbed by the villi. This is achieved by the enzyme peptidase that is produced in the epithelial cells of the intestinal villus.

6 Biology 12: Digestion Review Story Digestion of fat (butter) Fat is first emulsified by bile, a substance made by the liver and stored in the gall bladder. The contents of the latter enter the small intestine by way of the bile duct. After the fat has been emulsified, it is broken down by the enzyme lipase which is found in pancreatic juice, which enters the small intestine by way of the pancreatic duct. Fats are broken into glycerol and fatty acids, molecules small enough to be absorbed by intestinal villi. After resynthesis, fats enter the lacteal, which are part of the lymphatic system. 19. Path of food. a. Food consists of the large organic molecules proteins and carbohydrates and lipids and nucleic acids. In the mouth, the only type of food digested is starch. The mouth has a neutral ph. The food passes down the long tube called the esophagus. A rhythmic contraction called peristalsis pushes the food along. After passing through a sphincter, (circular muscle), the food enters the stomach where the primary food acted on is protein. The food, now called chyme, passes through another sphincter into the duodenum. Two ducts enter this organ: they are the pancreatic duct from the pancreas and the bile duct from the

7 Biology 12: Digestion Review Story 7 gall bladder. Bile contains an emulsifier which divides fat up into fat droplets. Pancreatic juice contains enzymes that act on lipids, protein, and carbohydrates Lining the walls of the intestine are epithelial cells with microvilli on the apical surface of each cell. The epithelial cells produce enzymes that finish digestion by converting maltose to glucose and peptides to amino acids. Thus the small nutrient molecules that are absorbed by the villi are Amino acids, glucose, nucleotide,and Fatty acids and glycerol. Fat products enter the lacteal and the other molecules enter the hepatic portal vein. This vein takes the nutrients to the liver,an organ of homeostasis. For example, this organ stores glucose as glycogen and always keeps the blood glucose level constant. This organ can also remove amino groups from amino acids and convert the amino groups to urea a nitrogenous waste product. 20. Digestive Enzyme Activity. For each combination of substances below, decide whether digestion will or will not occur at the maximum rate. Give an explanation if digestion will NOT occur maximally. a. trypsin, NaHCO 3, egg white, warm gently maximal rate

8 Biology 12: Digestion Review Story 8 b. salivary amylase, water, egg white, warm gently no reaction - wrong substrate! (amylase works on starch!) c. Pepsin, HCl, egg white, freeze no reaction - enzyme will not work when temperatures drop that low! d. pancreatic amylase, HCl, starch, heat to boiling no reaction - boiling denatures the enzyme (+ the ph is wrong!) e. lipase, NaHCO 3, fats, warm gently maximum rate f. maltase, HCl, maltose, warm gently will work, but not very well. Wrong ph g. peptidases, fat, HCl, warm gently no reaction - wrong substrate, + wrong ph h. pepsin, HCl, egg white, warm gently maximum rate i. trypsin, starch, water, warm gently no reaction - wrong substrate j. HCl, egg white, water, warm gently no reaction - no enzyme!

9 Biology 12: Digestion Review Story 9 Questions: 1. Name the Pancreatic enzyme that in the duodenum will: a. digest starch: It forms the product b. digest Protein: It forms the product c. digest fat droplets: It forms the product d. The end products of fat digestion in the epithelial cells to form a temporary fat carrier molecule called a. These carrier molecules are then dumped into the (part of the ) and will enter the blood-stream with the rest of the lymph at the left vein. 2. The 2 enzymes produced by the epithelial cells to complete the digestion of peptides and maltose are and The end products that are formed from these degradations are and. 3. Lactose intolerance is due to. The consequence of drinking milk for these individuals is 4. The stomach is directly connected to the above and the below. 5. The major food digested in the stomach is, which is hydrolyzed by the enzyme. 6. Among its chemical aspects, every digestive enzyme has a preferred &. 7. Before fats are digested by the enzyme, they are first emulsified by.

10 Biology 12: Digestion Review Story Pancreatic juices enter the small intestine by way of the duct and contain for the digestion of every type of food. 9. The liver first receives the products of digestion by means of the vein; any excess glucose is stored as 10. Surface area in the small intestine is increased greatly by the presence of and and. 11. List 6 functions of the Liver 14. a. In which part of the digestive tract are nutrient molecules absorbed? b. The absorbed nutrient molecules enter what vein associated with the intestine? c. In which part of the digestive tract does pancreatic juice enter? d. In which part of the digestive tract does bile enter?

11 Biology 12: Digestion Review Story 11 e. What parts of the digestive tract do not actually contain food and might be called accessory organs of digestion? f. What parts of the digestive tract do not have ducts entering them and do not secrete digestive juices? Digestion of Carbohydrate (starch) Starch digestion begins in the empty from the disaccharide. Here the ducts glands. The salivary juice contains the enzyme and this enzyme breaks down starch to the. Starch is also acted on in the. Here, a duct empties from the Pancreatic juice contains the enzyme disaccharide disaccharide is broken down to which breaks down starch to the. Starch digestion is complete when this, a monosaccharide, which can be absorbed by intestinal villi. The enzyme that converts maltose to glucose is called cells of the intestinal villus. and this enzyme is secreted by 17. Digestion of Protein (meat) Protein digestion begins in the line the wall of the stomach. They secrete the enzyme. The glands which breaks down protein to is secreted by the. Another enzyme called and this enzyme acts on protein in the

12 Biology 12: Digestion Review Story 12, also breaking down protein to. Protein digestion is complete when peptides are broken down to, molecules small enough to be absorbed by the villi. This is achieved by the enzyme that is produced in the epithelial cells of the intestinal villus. 18. Digestion of fat (butter) Fat is first emulsified by liver and stored in the small intestine by way of the emulsified, it is broken down by the enzyme, a substance made by the. The contents of the latter enter the duct. After the fat has been which is found in pancreatic juice, which enters the small intestine by way of the pancreatic duct. Fats are broken into and fatty acids, molecules small enough to be absorbed by intestinal villi. After resynthesis, fats enter the which are part of the lymphatic system. 19. Path of food. a. Food consists of the large organic molecules and and and. In the mouth, the only type of food digested is. The mouth has a ph. The food passes down the long tube called the. A rhythmic contraction called pushes the food along. After passing through a sphincter, (circular muscle), the food enters the where the primary food acted on is

13 Biology 12: Digestion Review Story 13. The food, now called chyme, passes through another sphincter into the. Two ducts enter this organ: they are the and the duct from the duct from the. Bile contains an which divides fat up into fat droplets. Pancreatic juice contains enzymes that act on,, and Lining the walls of the intestine are with on the apical surface of each cell. The epithelial cells produce enzymes that finish digestion by converting to glucose and to amino acids. Thus the small nutrient molecules that are absorbed by the villi are,,,and. Fat products enter the and the other molecules enter the portal vein. This vein takes the nutrients to the homeostasis. For example, this organ stores glucose as,an organ of and always keeps the blood glucose level constant. This organ can also remove amino groups from and convert the amino groups to a nitrogenous waste product.

14 Biology 12: Digestion Review Story Digestive Enzyme Activity. For each combination of substances below, decide whether digestion will or will not occur at the maximum rate. Give an explanation if digestion will NOT occur maximally. a. trypsin, NaHCO 3, egg white, warm gently b. salivary amylase, water, egg white, warm gently c. Pepsin, HCl, egg white, freeze d. pancreatic amylase, HCl, starch, heat to boiling e. lipase, NaHCO 3, fats, warm gently f. maltase, HCl, maltose, warm gently g. peptidases, fat, HCl, warm gently

15 Biology 12: Digestion Review Story 15 h. pepsin, HCl, egg white, warm gently i. trypsin, starch, water, warm gently j. HCl, egg white, water, warm gently