module 3 problem set
1. Name the two main divisions of the digestive system organs.
1. The human digestive organs can be divided into those of the alimentary canal and the accessory digestive organs.
10. Where are taste buds located?
10. Taste buds are found primarily on the tongue but also on the surface of the mouth and the wall of the pharynx.
11. Describe the function of the tongue in the digestive process.
11. The tongue grips the food, constantly repositions it between the teeth and forms it into a compact mass which is pushed back to the pharynx to begin the process of swallowing.
12. What is a bolus?
12. A bolus is the compact mass of food formed by the combination of chewing by the teeth and repositioning by the tongue.
13. List the 3 parts of the pharynx.
13. The pharynx is made up of three parts: the nasopharynx, the oropharynx, and the laryngopharynx.
14. Through what sections of the pharynx does air travel? Through what sections of the pharynx does food travel?
14. Air enters the nose, continues through the nasopharynx, oropharynx and the laryngopharynx. Air then enters the trachea on its way to the lungs. Food and liquid enter the mouth, continue through the oropharynx and the laryngopharynx but then continue into the esophagus.
15. What prevents food from entering the lungs and why is this necessary?
15. Food is prevented from entering the larynx by the epiglottis, a flap of elastic cartilage which covers the larynx when swallowing food or liquid.
16. Describe how the muscular layers in the pharynx assist with food passage.
16. The pharynx has two types of skeletal muscles; a circumferential outer layer and an inner longitudinal layer which contract alternatively squeezing food into the esophagus.
17. List and describe the tissue layers of the esophagus.
17. The esophagus contains 4 layers of tissue: the innermost layer is the mucosa which secretes mucus into the interior the gastrointestinal tract, the second layer is the submucosa which contains blood and lymph vessels, lymph nodes, nerves, and mucous glands, the third layer is the muscularis externa which is made of two layers of muscle: the outer longitudinal fibers and inner circumferential fibers and the outermost layer is the serosa which is made up of cells that make serous fluid.
18. Explain peristalsis.
18. Peristalsis is the squeezing of food through the GI tract by the alternating contraction of the sets of longitudinal and circumferential muscles.
19. What are the three main divisions of a tooth?
19. Each tooth is made of three main parts: the crown, the neck and the root
2. Name the seven parts of the gastrointestinal tract.
2. The gastrointestinal tract is composed of the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus.
20. What are the three types of papillae on the tongue? Which ones contain taste buds?
20. There are three types of papillae which help to grip food on the tongue: circumvallate, fungiform and filiform. Circumvallate and fungiform papillae both contain taste buds.
22. Describe the shape of the stomach and its location relative to the abdomen and diaphragm.
22. The stomach is a backward C shaped organ that is located along the left side of the abdomen below the diaphragm.
23. Describe the passage of food into and out of the stomach.
23. Food enters the stomach from the esophagus via the cardioesophageal sphincter and exits the stomach via the pyloric sphincter into the small intestine.
24. Describe the lesser curvature and the greater curvature.
24. The stomach has two curvatures: the concave lesser curvature which extends inward on the shorter side of the stomach and the convex greater curvature which extends outward on the longer side of the stomach.
25. Describe the lesser omentum and the greater omentum.
25. The lesser omentum is a serous membrane which attaches the lesser curvature of the stomach to the liver and the greater omentum is a serous membrane which attaches the greater curvature of the stomach to the posterior wall of the body.
26. List and describe the two functions of the stomach.
26. The stomach has two purposes. It is a temporary storage area for food, storing up to two liters of partially digested food. The muscular walls of the stomach contract vigorously and mix food with juices that are secreted whenever food enters the stomach, allowing food to be broken down into smaller pieces that are easier to digest.
27. The pH of stomach is 1.3 - 3.5. What is this due to and what is its source and function?
27. The 1.3-3.5 pH of stomach contents is due to hydrochloric acid secreted by the parietal cells. The high acidity level kills bacteria and converts the inactive pepsinogen into the active enzyme pepsin.
28. What is the source of the stomach enzyme pepsin and what is its function?
28. Inactive pepsinogen is secreted by the chief cells and converted into the active enzyme pepsin by HCl. Pepsin then begins the breakdown of proteins.
29. What is a stomach ulcer?
29. A stomach ulcer is an open sore in the wall of the stomach
3. Name the six digestive system accessory organs.
3. The accessory organs are the teeth, tongue, gallbladder, salivary glands, liver and pancreas.
30. Explain in detail how the stomach contents enter the small intestine.
30. The pyloric sphincter valve, located at the base of the stomach, relaxes causing a small quantity of chyme to pass through the opening into the first part of the small intestine. This initiates a reflex that causes the muscles of the sphincter to contract and close the opening temporarily. Then the sphincter relaxes again and allows more chyme to enter.
31. List the 3 sections of the small intestine. Which section is the shortest?
31. The first and shortest section of the small intestine is the duodenum. Second section is the jejunum and third is the ileum.
32. What are the names of the valves which are located at the beginning and end of the small intestine?
32. The small intestine runs from the pyloric sphincter at the end of the stomach to the ileocecal valve at the large intestine.
33. List the names of the 3 specialized structures in the wall of the small intestine.
33. The 3 specialized structures in the small intestine are circular folds, villi and microvilli.
34. Where is bile formed and stored?
34. Bile is formed in the liver which is stored in the gallbladder.
35. Describe in detail the 2 major functions of pancreatic juice.
35. Pancreatic juice contains sodium bicarbonate, which neutralizes the chyme and makes the pH of the small intestine slightly basic. Pancreatic juice also contains digestive enzymes that further digest every major component of food.
36. Describe how fats, sugars and amino acids are absorbed by the small intestine.
36. Each small intestinal villus contains blood vessels and a lacteal lymphatic vessel. Sugars and amino acids enter villi cells and then are absorbed into the bloodstream. Glycerol and fatty acids enter villi cells and are reassembled into fat molecules, which move into the lacteals.
37. What are the 3 functions of the liver that are important in digestion?
37. The 3 functions of the liver important in digestion are (1) it produces bile, which is stored in the gallbladder before entering the small intestine, where it emulsifies fats, (2) it stores glucose as glycogen and breaks down glycogen to glucose between meals to maintain a constant glucose concentration (homeostasis) in the blood, and (3) it produces urea from amino groups that are removed from excess amino acids.
38. List the 8 regions of the large intestine.
38. (1) Cecum, (2) appendix, (3) ascending colon, (4) transverse colon, (5) descending colon, (6) sigmoid colon, (7) rectum, (8) anal canal
39. What are the two sphincters of the anal canal?
39. The anal canal has an involuntary smooth muscle internal sphincter and a voluntary skeletal muscle external sphincter.
40. List 4 functions of the large intestine.
40. The large intestine propel wastes, reabsorbs water, reabsorbs electrolytes and absorbs Vitamin K and certain B vitamins produced by intestinal bacteria.
41. What are the 2 major physiological problems caused by diarrhea?
41. When materials pass through the colon too quickly, excess water is not reabsorbed, and diarrhea will result, which can lead to serious dehydration and electrolyte loss.
42. List the content of feces.
42. Feces are about 75% water and 25% solid matter containing intestinal bacteria, undigested plant material, fats, bile pigments, inorganic material, mucus, and dead intestinal cells.
44. Name the 4 main functions performed by the digestive system.
44. The digestive system has four main roles that it performs: ingestion, digestion (both mechanical and chemical), absorption, and defecation.
45. What digestive system functions are carried out by the mouth?
45. Ingestion and Digestion.
46. Explain which digestive system functions are carried out by the stomach.
46. In the stomach mechanical digestion continues as muscles churn and mix the food, breaking it into smaller pieces in the form of chime which is moved to the small intestine by peristalsis. Chemical digestion continues as pepsin digests proteins.
47. Explain which digestive system functions are carried out by the small intestine.
47. In the small intestine chemical digestion continues as enzymes from the pancreatic juices break down starches and proteins, and begin digestion of fat. Mechanical digestion continues as bile breaks down fat into smaller pieces. Absorption begins as digested food molecules, water and fat are absorbed into the bloodstream.
48. Explain the two main hormones that are responsible for hunger and satiety.
48. Leptin and Ghrelin. Leptin is produced by adipose tissue (fat cells). The role of leptin is to alert the brain to turn off the hunger center in the brain and activate the satiety center when consuming a meal. Ghrelin is produced by the stomach and has the opposite role. Ghrelin travels to the brain and stimulates the hunger center as it deactivates the satiety center. Ideally, leptin and ghrelin work together to balance hunger and satiety.
49. List the 5 biochemical materials needed by the body that are found in food.
49. Carbohydrates, proteins, and lipids are the major biochemical substances found in food needed by the body in large amounts. Vitamins and minerals are also needed in a much smaller amount.
50. What are the 2 classes of carbohydrates and in what foods can each be found?
50. Carbohydrates are classified as starches and sugars. Milk and fruits such as apples or peaches contain sugar, while grains such as wheat and vegetables such as potatoes contain starches.
51. What are the 3 classes of lipids?
51. Lipids can be divided into three categories: saturated fat, unsaturated fat, and cholesterol.
52. What are the 2 classes of proteins and in what foods can each be found?
52. Proteins can be categorized as complete or incomplete proteins. Examples of complete proteins are meat, poultry, eggs, milk or dairy products, and soybeans; whereas, examples of incomplete proteins are grains, legumes, seeds, and nuts.
53. What is the definition of an essential amino acid, how many essential amino acids are there for adults and where can they be found?
53. There are nine amino acids called essential amino acids required in an adult human diet since the body is unable to make these amino acids. Complete proteins contain all nine essential amino acids.
54. What are the 2 classes of vitamins? How is a vitamin different than a carbohydrate, lipid or protein? Why can ingestion of excessive amounts of one type of vitamin be dangerous?
54. The 2 classes of vitamins are water-soluble vitamins and fat-soluble vitamins. Vitamins are organic compounds that are not consumed in metabolic reaction but help enzymes carry out the metabolic reactions which convert nutrients to materials need by the body. Fat-soluble vitamins are stored in body fat and ingestion of excessive amounts can be problematic.
55. List 2 ways in which minerals are different than carbohydrates, lipids and proteins. List the seven minerals needed in the human diet and four foods which are good sources of these.
55. Minerals are inorganic compounds (not organic like carbohydrates, lipids and proteins) and are not used as fuel in metabolic reactions. Humans need the following seven minerals in their diets: calcium, chloride, magnesium, phosphorus, potassium, sodium, and sulfur. Foods such as milk, some meats, legumes and vegetables are the best sources of minerals.
56. Define anabolism.
56. Anabolism is the set of reactions in which smaller molecules are combined to make larger molecules.
57. How is the energy released from the breakdown of glucose used by the body?
57. The energy is released during the breakdown of glucose is used by the body to add a phosphate to an adenosine diphosphate (ADP) molecule and make adenosine triphosphate (ATP).
58. Describe cellular respiration.
58. During cellular respiration, glucose combines with oxygen to form carbon dioxide, water, and ATP.
59. Describe glycolysis.
59. In glycolysis glucose is broken down into two pyruvic acid molecules and two ATP molecules are formed.
6. List the two bones and the membrane to which the tongue is attached.
6. The tongue is attached to the hyoid bone and the mandible and the membranous lingual frenulum.
60. Describe the citric acid cycle (TCA cycle).
60. In the citric acid (TCA) cycle the pyruvic acid product of glycolysis is converted to carbon dioxide forming some additional ATP.
61. Describe the electron transport chain.
61. In the electron transport chain hydrogen atoms formed during glycolysis and the TCA cycle are converted to water releasing energy which is used to add phosphate to ADP to form ATP.
62. How is the energy released in the breakdown of glucose converted to a form usable by the cells?
62. The energy released in the breakdown of glucose allows the body to add a phosphate to an adenosine diphosphate (ADP) molecule and make adenosine triphosphate (ATP) which is then used by cells as a source of energy to perform cellular activities.
63. How does the energy formed in fat catabolism compare to that formed in carbohydrate metabolism?
63. Lipid metabolism yields twice the energy formed during glucose metabolism.
64. Name, tell the location of and explain in detail the first stage of lipid breakdown.
64. Lipid metabolism occurs in the liver by a process known as beta-oxidation to form acetic acid which is further catabolized by the TCA cycle to carbon dioxide forming some ATP.
65. Why are proteins not usually used as a body energy source and when are they used?
65. Proteins are the building blocks for the cells and are therefore preserved by the body only being used to make ATP when carbohydrates and fats are unavailable to the body.
66. What is the first step in the oxidation of an amino acid formed from a protein?
66. When proteins must be used to form ATP, the amino group is removed from the protein to form ammonia.
67. Explain in detail how ammonia is removed from the body.
67. Ammonia is combined with carbon dioxide to make urea which is excreted in the urine.
7. How many teeth are there in an adult human and what do they do?
7. There are thirty-two teeth in the human mouth. Together they work to tear, crush and grind food to mechanically digest food.
8. What are the four types of teeth, how many of each type are there and what does each type do?
8. The teeth are composed of two chisel-shaped incisors for biting; one pointed canine for tearing; two fairly flat pre-molars for grinding; and three flat molars for crushing.
9. What is the specific function of the salivary gland in the process of digestion?
9. Food is mixed and moistened with saliva (from the salivary glands) containing enzymes that begin the process of chemical digestion by breaking down starches.
5. What structures respectively form these parts of the mouth? a. Opening b. Floor c. Walls d. Roof
a. Opening = Lipsb. Floor = Tonguec. Walls = Cheeksd. Roof = Hard/soft palates
