9. Gastrointestinal System Flashcards
1
Q
- Which of the following statements is WRONG? The end products of:
A. Protein digestion products are transported to the liver via the hepatic portal vein
B. Triglyceride digestion products are transported to the liver via the lymphatic system
C. Carbohydrate digestion products are transported to the liver in the blood
D. Triglyceride digestion products are transported via the lymphatic system
A
Answer is B: The products of fat digestion are transported by the lymphatic system but do not pass through the liver.
2
Q
- One of the following processes is NOT part of mechanical digestion. Which one?
A. Hydrolysis
B. Peristalsis
C. Segmentation
D. Mastication
A
Answer is A: Hydrolysis is a chemical process that coverts large food molecules into smaller ones (i.e. performs digestion)
3
Q
- Which type of cell produces hydrochloric acid?
A. Zymogenic cells
B. Parietal cells
C. Chief cells
D. Enteroendocrine cells
A
Answer is B: The parietal cells of gastric glands produce hydrochloric acid. (Zymogenic cells are the same as chief cells; they produce pepsinogen.)
4
Q
- Which of the following glands are accessory organs of the digestive system?
A. Adrenal glands
B. Pancreatic islets
C. Gastric glands
D. Salivary glands
A
Answer is D: Salivary glands produce a secretion (saliva) that empties into the digestive tract via a tube. (Pancreatic islets are in the pancreas but are themselves not a gland.)
5
Q
- What is the role of gastrin in the digestive system?
A. To stimulate release of bile and pancreatic juice
B. To stimulate gastric secretion
C. To activate pepsinogen
D. To hydrolyse proteins to polypeptides
A
Answer is B: Gastrin is a hormone that stimulates gastric secretion (from the stomach wall).
6
Q
- Which liver cells produce bile?
A. Kupffer cells
B. Sinusoids
C. Hepatocytes
D. The acini
A
Answer is C: Hepatocytes are liver cells. Kupffer cells are macrophages, while sinusoids are blood capillaries
7
Q
- What are the end products of carbohydrate digestion?
A. Chylomicrons
B. Amino acids
C. Free fatty acids
D. Monosaccharides
A
Answer is D: Monosaccharides or “simple” sugars.
8
Q
- What feature of the small intestine enhances its ability to absorb digested food?
A. Its large surface area
B. The gaps between adjacent epithelial cells
C. Secretion of the hormone absorption
D. Its longer length compared to the large intestine
A
Answer is A: The large surface area allows the products of digestion ample opportunity to make contact with the absorbing surface.
9
Q
- Which of the following gut structures are listed in the correct order that food would pass through them, from input to exit?
A. Pyloric sphincter, ileum, jejunum, transverse colon
B. Pancreas, jejunum, ascending colon, sigmoid colon
C. Ileum, duodenum, descending colon, ascending colon
D. Duodenum, ileum, caecum, transverse colon
A
Answer is D: Jejunum is before the ileum; food does not pass through the pancreas; duodenum is before the ileum.
10
Q
- Which statement about the layers of the alimentary canal is correct?
A. The serosa absorbs the products of digestion.
B. The mucosa protects against self-digestion.
C. The submucosa is involved in segmentation and peristalsis.
D. The muscularis externa is dense connective tissue.
A
Answer is B: The mucosa (not serosa) absorbs the products of digestion; the muscularis externa causes segmentation and peristalsis; the submucosa (not muscularis) is a dense connective tissue.
11
Q
- Which of the following pairs of substances are NOT secreted by the stomach as part of “gastric juice”?
A. Hydrochloric acid and pepsinogen
B. Hormones and intrinsic factor
C. Nuclease and amylase
D. Mucus and gastrin
A
Answer is C: Nuclease and amylase are enzymes secreted by the pancreas.
12
Q
- What are some products of lipid digestion?
A. Free bases and pentose sugars
B. Fructose and glucose
C. Amino acids and small peptides
D. Free fatty acids and monoglycerols
A
Answer is D: Lipids are digested into free fatty acids and monoglycerols.
13
Q
- From which of the gut structures below is most digested food absorbed?
A. Duodenum
B. Stomach
C. Ileum
D. Ascending colon
A
Answer is C: The ileum is part of the small intestine distal to the duodenum which has a structure suited to absorption.
14
Q
- Which of the following is an active enzyme?
A. Procarboxypeptidase B. Pepsin
C. Telophase
D. Trypsinogen
A
Answer is B: The prefix “pro-” and suffix “-ogen” refer to inactive enzymes. Telophase is a stage of cell division (not an enzyme).
15
Q
- Which of the following is a function of the liver?
A. Recycling of non-viable red blood cells
B. Conversion of pyruvic acid to lactic acid
C. Synthesis of plasma proteins
D. Production of renin
A
Answer is C: The liver produces many proteins (spleen recycles RBC; liver converts lactic acid back into pyruvic acid; kidney produces renin).
16
Q
- What is the term applied to the production of glucose from noncarbohydrate molecules?
A. Deamination
B. Transamination
C. Glycogenolysis
D. Gluconeogenesis
A
Answer is D: Gluco refers to glucose; neo = new; and genesis = producing (glyco- genolysis is the production of glucose from glycogen – by lysis.)
17
Q
- Which of the following terms is used to describe the changing of large food molecules into smaller molecules?
A. Mechanical digestion B. Deglutition
C. Segmentation
D. Hydrolysis
A
Answer is D: Hydrolysis refers to the splitting (lysis) of large molecules into smaller ones using water (hydro).
18
Q
- What is the purpose of “intrinsic factor” in gastric juice?
A. To activate pepsinogen.
B. To assist with the absorption of vitamin B12.
C. To protect the stomach lining against hydrochloric acid.
D. It stimulates the release of gastrin.
A
Answer is B: Vitamin B12 is a large molecule which cannot be absorbed without forming a complex with intrinsic factor.
19
Q
- Which of the following does NOT contribute to increasing the surface area of the small intestine?
A. The brush border
B. Plicae circulars
C. Intestinal crypts
D. Villi
A
Answer is C: The crypts produce the secretion known as intestinal juice.
20
Q
- What are the end-products of carbohydrate digestion?
A. Monosaccharides
B. Disaccharides
C. Glucose
D. Risaccharides
A
Answer is A: Glucose is one example of a monosaccharide, but there are others.
21
Q
- Name the major cell type in a liver lobule.
A. Kupffer cells
B. Hepatocytes
C. Sinusoids
D. Epithelial cells
A
Answer is B: Hepato- = liver. Kupffer cells also occur in the liver but are macrophages.
22
Q
- To what does the term “gluconeogenesis” refer?
A. The conversion of glycogen to glucose
B. The removal of an amine group from an amino acid
C. The production of glucose from noncarbohydrate molecules
D. The conversion of disaccharides to monosaccharides
A
Answer is C: “-Neogenesis” refers to making glucose from something new (that is not a carbohydrate).
23
Q
- Which of the following is TRUE of bile?
A. It converts inactive pancreatic enzymes to active form.
B. Needed in the small intestine for the digestion of fats.
C. Synthesised by the gall bladder.
D. Needed in the small intestine for the emulsification of fats.
A
Answer is D: Bile emulsifies (rather than digests) fat. It is stored (but not synthesised) in the gall bladder
24
Q
- Why are the blood capillaries in the liver lobules so permeable?
A. To allow the products of digestion to leave the blood for processing in the liver
B. To allow fatty acids to leave the liver cells to enter the blood
C. To allow plasma proteins that are synthesised in the liver to enter the blood
D. To allow red blood cells at the end of their life to leave the blood to be recycled in the liver
A
Answer is C: Plasma proteins are large molecules that otherwise would not be able to enter (or leave) blood capillaries.
25
25. Which layer of the gastrointestinal tract is in contact with the contents of the gut?
A. Muscularis externa
B. Mucosa
C. Serosa
D. Submucosa
Answer is B: It secretes mucus and absorbs the products of digestion.
26
26. What is the name given to the process of moving the gut contents along the tract in the right direction?
A. Peristalsis
B. Emesis
C. Segmentation
D. Deglutition
Answer is A: Segmentation is “to and fro” movement about the one spot.
27
27. Which of the following substances is NOT produced by the cells of the gastric glands?
A. Mucus
B. Hydrochloric acid
C. Gastrin
D. Pepsin
Answer is A: Mucus cells are in the epithelium, not in the gastric glands, and produce mucus.
28
28. Which hormone stimulates the release of bile and pancreatic juice?
A. Cholecystokinin
B. Secretin
C. Intestinal gastrin
D. Pepsin
Answer is A: Duodenum produces and releases CCK when protein and fats enter the duodenum.
29
29. What molecules are the products of protein hydrolysis?
A. Monoglycerols and free fatty acids
B. Monosaccharides and disaccharides
C. Amino acids
D. Amino acids and small peptides
Answer is D: Amino acids and small peptides (consisting of two or three amino acids) are hydrolysis products of proteins.
30
30. What happens to the products of lipid digestion in the gut?
A. They are actively transported into the epithelial cells lining the gut.
B. They diffuse into epithelial cells and are reconstituted into triglycerides.
C. They are transported to the liver by the hepatic portal vein.
D. They diffuse through the plasma membrane of epithelial cells and then diffuse into blood capillaries
Answer is B: Fats, being lipid soluble, diffuse into epithelial cells to be reconstituted into triglycerides.
31
31. One of these processes is NOT part of carbohydrate metabolism in the liver. Which one?
A. Production of ATP from glucose
B. Production of glucose from glycogen
C. Production of glucose from amino acids
D. Production of glycogen from glucose
Answer is A: ATP production occurs in the mitochondria of cells and is called cellular respiration (rather than carbohydrate metabolism).
32
32. The liver contains “leaky capillaries” known as sinusoids. This enables what liver product to enter the bloodstream?
A. Angiotensinogen
B. Kupffer cells
C. Plasma proteins
D. Cholesterol
Answer is C: Plasma proteins are large molecules that otherwise would not be able to enter (or leave) blood capillaries.
33
33. What is the function of bile salts?
A. To assist the absorption of digested lipids
B. To emulsify lipids
C. To hydrolyse lipids
D. To digest lipids
Answer is B: Emulsification produces small droplets of fat which increases the surface area of fat that is available to lipases which may then hydrolyse the fat.
34
34. Digestion of food molecules is necessary so that:
A. Indigestible food molecules are separated from digestible food molecules
B. Essential amino acids and fatty acids may be absorbed by the body
C. Excretion of waste products can occur via the bowel
D. Food may be converted into particles small enough to pass into the cells of
the gut wall
Answer is D: The production of molecules that are small enough to be absorbed into epithelial cells is the purpose of digestion.
35
35. Where is the gastro-oesophageal sphincter?
A. Between the stomach and the duodenum
B. Between the stomach and the caecum
C. At the entrance to the stomach
D. Before the external anal sphincter
Answer is C: It is where the oesophagus enters the stomach. It prevents the stomach contents refluxing into the oesophagus.
36
36. What are the end products resulting from the digestion of carbohydrates?
A. Monosaccharides
B. Monoglycerols
C. Pentose sugars
D. Amino acids
Answer is A: Digestion results in carbohydrates (which are polysaccharides) being converted to monosaccharides (which are small molecules).
37
37. Which sections of the gut perform the majority of the digestion of food and absorption of the digested products?
A. Stomach and duodenum
B. Jejunum and ileum
C. Ascending colon and transverse colon
D. Duodenum and jejunum
Answer is D: While a small amount of digestion and absorption occurs in the stomach, most occurs in the duodenum (which receives pancreatic enzymes and bile) and the jejunum (which is adapted for absorption).
38
37. Which sections of the gut perform the majority of the digestion of food and absorption of the digested products?
A. Stomach and duodenum
B. Jejunum and ileum
C. Ascending colon and transverse colon
D. Duodenum and jejunum
Answer is D: While a small amount of digestion and absorption occurs in the stomach, most occurs in the duodenum (which receives pancreatic enzymes and bile) and the jejunum (which is adapted for absorption).
39
38. Which enzyme below digests proteins?
A. Nuclease
B. Maltase
C. Carboxypeptidase
D. Transaminase
Answer is C: The syllable “-peptid-” refers to proteins (which are polypeptides).
40
39. To what does the term “gluconeogenesis” refer?
A. The conversion of noncarbohydrate molecules to glucose
B. The formation of non-essential amino acids from a keto acid
C. The removal of an amine group from a molecule
D. The release of glucose from stored glycogen
Answer is A: “-Neogenesis” refers to making something (glucose) from new (a molecule that is not a carbohydrate).
41
40. A lobule of the liver contains several blood vessels. Which one carries nutrient- rich blood from the small intestine?
A. Hepatic artery proper B. Hepatic portal vein
C. Central vein
D. Bile ductule
Answer is B: “Portal” refers to a vein that transports blood from one capillary bed to another (rather than returning it to the heart).
42
41.
Which of the following could NOT be used to describe pepsinogen?
A. It is a protein.
B. It is a hormone.
C. It is related to an enzyme.
D. It is inactive.
Answer is B: Pepsinogen is an inactive protein enzyme. But it is not a hormone.
43
42. What is the function of the oesophagus in digestion?
A. It is a site of mechanical digestion.
B. It transfers food from the mouth to the stomach.
C. The oesophagus secretes amylase to begin carbohydrate digestion.
D. The oesophagus secretes hydrochloric acid.
Answer is B: It is merely a conduit to transfer food from the mouth to the stomach while bypassing the thoracic structures.
44
43. What is the purpose of the mucosal barrier between the cells of the stomach wall and the stomach contents?
A. It prevents the enzymes in the stomach contents from digesting the stomach.
B. It converts pepsinogen to its active form.
C. It prevents bacteria in the stomach from invading the stomach wall.
D. It prevents undigested food molecules from being absorbed by the stomach
lining.
Answer is A: The stomach contents include the enzyme pepsin and hydrochloric acid, both of which would damage the epithelial cells of the stomach if in contact with them.
45
44. Which parts of the alimentary canal prepare food for chemical digestion?
A. The mouth, oesophagus and stomach
B. The mouth, stomach and small intestine
C. The mouth, stomach and duodenum
D. The teeth, stomach and pancreas
Answer is C: The mouth (mastication and mixing with saliva), the stomach (churning) and the duodenum (segmentation). Choice C is better than choice B as digestion has occurred before food reaches the distal parts of the SI.
46
45. What food is digested by lipase?
A. Nucleic acids
B. Carbohydrates
C. Polypeptides
D. Triglycerides
Answer is D: Lipase digests lipids. Our dietary lipids are triglycerides.
47
46. What food is digested into monoglycerols?
A. Protein
B. Lipid
C. Nucleic acid
D. Starch
Answer is B: Dietary lipids are triglycerols which are digested into free fatty acids and monoglycerols.
48
47. What is the function of bile?
A. Bile hydrolyses polypeptides.
B. Bile emulsifies fats and oils.
C. Bile activates procarboxypeptidase.
D. Bile stimulates the pancreas to secrete pancreatic juice.
Answer is B: Emulsification of fats is the function of bile salts.
49
48. The liver is able to deaminate amino acids forming ammonia in the process. What happens to the ammonia?
A. It is phagocytosed by Kupffer cells.
B. It is used in transamination to form non-essential amino acids.
C. It is converted to bile to be excreted via the gut.
D. It is converted to urea for excretion by the kidneys.
Answer is D: Urea is the molecule and vehicle for excretion of human nitrogenous waste.
50
49. What happens to the products of digestion of lipids? They are absorbed into a:
A. Capillary and transported by the blood to the liver
B. Capillary and transported by the blood to the heart
C. Lacteal and transported by the lymph to the heart
D. Lacteal and transported by the lymph to the liver
Answer is C: Digested fats absorbed from the gut are transported in the lymph. They re-enter the bloodstream via the thoracic duct and then travel to the heart.
51
50. If blood glucose is high, what does the liver do about it?
A. The liver converts glucose to glycogen or triglycerides.
B. The liver performs glycogenolysis.
C. The liver performs gluconeogenesis.
D. The liver transaminates glucose to produce amino acids.
Answer is A: This process removes glucose from circulation. Choices B and C would increase blood glucose. Transamination is done to amino acids to produce different amino acids.
52
51. Which is an enzyme secreted by the gastric glands?
A. Pepsin
B. Gastrin
C. Cholecystokinin
D. Intrinsic factor
Answer is A: Pepsin (strictly pepsinogen) is the only enzyme on the list.
53
52. What are the products of protein digestion?
A. Monoglycerols and fatty acids
B. Dipeptides, tripeptides and amino acids
C. Bases, pentose sugars and nitrate ions
D. Monosaccharides and disaccharides
Answer is B: Peptides and amino acids are produced by the hydrolysis of protein.
54
53. Which three sections do the small intestine consists of?
A. Ileum duodenum, caecum
B. Antrum, jejunum, duodenum
C. Rectum, ileum, duodenum
D. Ileum, duodenum, jejunum
Answer is D: Caecum is part of the LI; antrum is part of the stomach; rectum is the last part of the colon.
55
54. What name is given to the movement of food material through the gastrointes- tinal tract?
A. Peristalsis
B. Segmentation
C. Deglutition
D. Bowel movement
Answer is A: While segmentation is also movement, it is a to and fro movement rather than unidirectional, so peristalsis is the best answer.
56
55. Correctly complete the sentence: Pepsinogen is
A. Converted to pepsin by hydrochloric acid
B. Converted to pepsin by intrinsic factor
C. Secreted by the pancreas
D. Involved in production of carbohydrate digesting enzymes
Answer is A: Pepsinogen “gen”erates pepsin in the presence of hydrochloric acid.
57
56. Emulsification is the name of the process carried out by:
A. Lipase
B. Bile
C. Micelles
D. Lacteals
Answer is B: Bile contains “surfactants” which congregate on the interface between lipid and water and so prevent small droplets of fat from aggregating into larger ones (=emulsification).
58
57. The pH of the stomach and the pH of the small intestine are BEST described (respectively) as:
A. Acidic and alkaline/basic
B. Strongly acidic and weakly alkaline/basic
C. Acidic and weakly alkaline/basic
D. Strongly acidic and strongly alkaline/basic
Answer is B: The pH of the stomach contents is about 2 (strongly acidic), while the pH of the small intestine is about 8 (weakly alkaline). Thus B is the best answer.
59
58. What feature do procarboxypeptidase, pepsinogen, fibrinogen and chymotryp- sinogen have in common?
A. They are all enzymes.
B. They are all produced by the pancreas.
C. They are all inactive.
D. They all digest proteins.
Answer is C: The prefix and suffix “pro- ” and “-ogen” refer to these molecules needing modification to become enzymes. In their present form, they are inactive.
60
59. Which layer of the alimentary canal is responsible for absorbing the products of digestion?
A. Muscularis interna
B. Mucosa
C. Serosa
D. Submucosa
Answer is B: The mucosal layer is in closest proximity to the contents of the canal and digested material must pass through it.
61
60. Protein is digested to polypeptides by which of the following?
A. Pepsinogen
B. Intrinsic factor
C. Hydrochloric acid
D. Pepsin
Answer is D: Pepsinogen is inactive (otherwise it would digest the proteins with the zymogenic/chief cells) until converted to pepsin by HCl.
62
61. What are the products of carbohydrate digestion?
A. Monosaccharides
B. Amino acids
C. Monoglycerides
D. Monogylcerols
Answer is A: Carbohydrates are digested into simple sugars known as monosaccharides (e.g. glucose, fructose, ribose).
63
62. What does bile do?
A. Bile stimulates the release of lipase.
B. Bile emulsifies fat.
C. Bile digests fat.
D. Bile hydrolyses fat.
Answer is B: Emulsification of fat is the role played by bile.
64
63. What is the function of the hepatic portal vein?
A. To return blood from the liver to the heart
B. To transport blood rich in amino acids, monosaccharides and free fatty
acids to the liver
C. To transport the products of protein and carbohydrate digestion from the gut to the liver
D. To allow the nutrients absorbed from the gut to bypass the liver.
Answer is C: The digestion products of protein and carbohydrate (but not of triglycerides) are transported to the liver by the portal vein.
65
64. Which of the following are the end products of protein hydrolysis?
A. Monoglycerols
B. Keto acids and non-essential amino acids
C. Polypeptides
D. Amino acids and di- and tripeptides
Answer is D: Amino acids are the smallest molecules resulting from protein hydro- lysis. Some two amino acid units (dipeptides) and three amino acid units (tripep- tides) can also be absorbed from the gut.
66
65. One of the following is NOT a function of the liver. Which one?
A. Recycling of red blood cells
B. Storage of fat-soluble vitamins
C. Removal and recycling of lactic acid
D. Activation of vitamin D
Answer is A: Red blood cells are recycled in the spleen.
67
66. Which of the following is NOT a part of the gastrointestinal tract?
A. Ileum
B. Pancreas
C. Rectum
D. Caecum
Answer is B: Pancreas is an accessory gland outside of the GI tract but delivers its secretion via a duct.
68
67. What converts pepsinogen to pepsin in the stomach?
A. Hydrochloric acid
B. Gastrin
C. Intrinsic factor
D. Pepsinase
Answer is A: HCl cleaves off 44 amino acids from pepsinogen to form pepsin.
69
68. What the products of hydrolysis of lipids?
A. Monosaccharides
B. Chylomicrons
C. Amino acids and small peptides
D. Free fatty acids and monoglycerols
Answer is D: A triglyceride is hydrolysed into two free fatty acids plus a monoglycerol. Chylomicrons are the structure within which fats are transported in the lymph and blood.
70
69. Why are sinusoids the type of capillaries found within a liver lobule?
A. To allow for mixing of blood from the hepatic artery and the hepatic portal vein
B. So that liver-synthesised plasma proteins may enter the blood
C. To allow worn out red blood cells to leave the bloodstream.
D. In order for the products of digestion to be removed from the blood
Answer is B: The epithelial cells that make up sinusoids have gaps between them large enough for plasma proteins to fit through and to enter the blood.
71
71. What is the function of bile salts?
A. To digest dietary fats through hydrolysis
B. To excrete the products haeme breakdown
C. To emulsify ingested fats and oils
D. To activate trypsinogen and chymotrypsinogen
Answer is C: Emulsification is the function of bile salts (not hydrolysis). Some materials are excreted via the gut by incorporating the waste into bile, but not as bile salts.
72
72. Which of the functions below is NOT performed by the liver?
A. Production of glucagon
B. Synthesis of lipoproteins to transport fatty acids
C. Deamination of amino acids to form keto acids
D. Conversion of noncarbohydrate molecules to glucose
Answer is A: Glucagon is a hormone that is produced by the pancreas.
73
73. What is the function of gastrin?
A. To facilitate the absorption of vitamin B12 from the gut
B. To inhibit gastric secretion
C. To stimulate gastric secretion
D. To stimulate pancreatic secretion
Answer is C: Gastrin is a hormone that stimulates the cells lining the stomach gastric pits to secrete.
74
74. Which list of sections of the intestine has them in correct order from nearest to furthest from the mouth?
A. Duodenum caecum, jejunum, ileum
B. Caecum, sigmoid colon, transverse colon, rectum
C. Duodenum, ileum, rectum, jejunum,
D. Jejunum, ileum, caecum, ascending colon
Answer is D: Caecum is after the ileum; sigmoid colon is after the transverse colon; jejunum is before the ileum.
75
75. Forward movement of food material through the gastrointestinal tract is achieved by which process?
A. Peristalsis
B. Emesis
C. Deglutition
D. Hydrolysis
Answer is A: Peristalsis is the name given to the smooth muscle movements that propel the gut contents.
76
76. What are the cells in the pancreas that secrete “pancreatic juice” called?
A. Hepatocytes
B. Peyer’s patches
C. The acini
D. Islets of Langerhans
Answer is C: Hepatocytes are in the liver; Peyer’s patches are lymphoid tissue in the gut wall; the islets produce insulin and glucagon.
77
77. The lowest pH is found in which of the listed body sites?
A. Pancreas
B. Stomach
C. Duodenum
D. Blood
Answer is B: The stomach has the lowest pH (is the most acidic), pH <2.
78
78. Which of the following is a function of bile?
A. To attach to vitamin B12 to allow it to be absorbed
B. To activate trypsinogen, chymotrypsinogen and procarboxypeptidase
C. To digest fats
D. To disperse large lipid globules into smaller droplets
Answer is D: This is known as emulsification.
79
79. What is the process that splits carbohydrates in the gut into smaller molecules called?
A. Catalysis
B. Hydrolysis
C. Catabolism
D. Glycogenolysis
Answer is B: Glycogenolysis also splits a carbohydrate (glycogen) into smaller molecules (glucose), but this happens in the liver.
80
80. What is true about the “muscularis externa”?
A. It is a muscle used for peristalsis.
B. It secretes mucus.
C. It refers to superficial skeletal muscles.
D. It is composed of connective tissue.
Answer is A: Muscularis externa is a layer (a tunic) of the gut wall.
81
81. The surface area available for absorption in the small intestine is increased by
all of the following structures EXCEPT one. Which one?
A. Villi
B. Haustra
C. Plicae circularis
D. Microvilli
Answer is B: Haustra are pouches (or sacculations) in the large intestine that do NOT occur in the small intestine.
82
82. The majority of dietary lipids are ingested in the form of:
A. Trisaccharides
B. Tripeptides
C. Cholesterol
D. Triglycerides
Answer is D: Triglycerides (or triacylglycerols) are the major component of human dietary lipids.
83
83. Emulsification is the process where:
A. Procarboxypeptidase and chymotrypsinogen become active enzymes.
B. Chyme is moved backwards and forwards across the surface of the small
intestine.
C. Fat droplets are dispersed into smaller droplets.
D. Dietary fat is digested by lipase.
Answer is C: Producing smaller droplets of fat increases the surface area available for lipase and allows digestion to proceed faster.
84
84. Kupffer cells are macrophages. Where are they found?
A. In the lymphatics of the submucosa and devour bacteria that escape the gut.
B. In the lumen of the large intestine and feed on our normal flora to produce vitamin K.
C. They are in the stomach wall as part of the mucosal barrier.
D. They occur in liver sinusoids and engulf bacteria in blood coming from the gut.
Answer is D: They are in the liver sinusoids (capillaries).
85
85. One of the following statements is UNTRUE. Which one?
A. Glucose is produced during the manufacture of ATP.
B. Glycogenolysis is the process of releasing glucose from glycogen.
C. Gluconeogenesis is the conversion of amino acids to glucose.
D. The monosaccharides galactose and fructose can be converted to glucose.
Answer is A: In fact the reverse is true. Glucose is consumed during the production of ATP.
86
86. Monosaccharides are the product of digestion of what substance?
A. Proteins
B. Carbohydrates
C. Triglycerides
D. Dipeptides
Answer is B: Carbohydrates are composed of many monosaccharide units.
87
87. One of the following is NOT a function of the large intestine. Which one?
A. Absorption of electrolytes
B. Synthesis of some vitamins
C. Absorption of water
D. Digestion of fats
Answer is D: Digestion occurs and is completed in the small intestine.
88
88. How are the pH of the small intestine and the pH of the stomach (respectively) best described?
A. Alkaline (basic) and acidic
B. Weakly alkaline (basic) and strongly acidic
C. pH of 4 and pH of 8
D. pH of 7 and pH of 1.5
Answer is B: The pH of the stomach contents is about 2 (strongly acidic), while the pH of the small intestine is about 8 (weakly alkaline). The numbers in choices C and D are wrong. Thus B is the best answer.
89
89. Which of the following is an enzyme?
A. Amylase
B. Gastrin
C. Intrinsic factor
D. Pepsinogen
Answer is A: Amylase is the only enzyme. Pepsinogen is not an enzyme until it is changed to pepsin.
90
90. Choose the list which has the selected structures of the alimentary canal in the same order that chyme would pass through them.
A. Larynx, jejunum, ileum, descending colon, transverse colon, sigmoid colon
B. Mouth, pharynx, oesophagus, large intestine, small intestine, anus
C. Oesophagus, stomach, duodenum, ascending colon, sigmoid colon, rectum
D. Stomach, duodenum, ileum, descending colon, transverse colon, ascending
colon
Answer is C: Descending colon is after the transverse colon; small intestine is before the large intestine.
91
91. What feature do procarboxypeptidase, pepsinogen, trypsinogen, chymotrypsinogen have in common?
A. They are all enzymes.
B. They are all produced by the pancreas.
C. They all digest proteins.
D. They are all inactive.
Answer is D: They are inactive so are not yet enzymes; when activated they would digest proteins, but not in their present form.
92
92. The products of fat digestion are absorbed into the epithelial cells of the intestinal wall differently from the way products of protein and carbohydrate digestion are. The reason is:
A. The products of protein and carbohydrate digestion are smaller.
B. The products of fat digestion are actively transported across the plasma membrane.
C. The products of fat digestion are smaller.
D. Monoglycerides are soluble in the plasma membrane.
Answer is D: The products of fat digestion are fat (lipid) soluble so can penetrate the plasma membrane which is made of lipid.
93
93. Which fluid within the body is likely to have the LOWEST pH?
A. The chyme in the ileum
B. Saliva
C. The blood
D. The chyme in the stomach
Answer is D: The stomach contents are the most acidic, that is, has the lowest pH.
94
94. What pancreatic enzyme digests lipids to free fatty acids and monoglycerides?
A. Lipase
B. Bile
C. Cholecystokinin
D. Lingual lipase
Answer is A: The “lip-” part of lipase indicates that it digests lipids, while the “-ase” part is indicative of an enzyme. Lingual lipase is produce by the salivary glands, not the pancreas.
95
95. What is the product of carbohydrate digestion?
A. Glucose
B. Monosaccharides
C. Glycogen
D. ATP
Answer is B: Glucose is a monosaccharide, but there are others, so choice B is the better answer.
96
96. Which of the following structures produce bile?
A. The gall bladder
B. The liver
C. The pancreas
D. The duodenum
Answer is B: Bile is a liver product that is stored in the gall bladder.
97
97. What is a function of the stomach?
A. Absorb the products of digestion
B. Participate in deglutition
C. Participate in mechanical digestion
D. Release cholecystokinin
Answer is C: The churning of chyme is part of mechanical digestion. While some simple molecules (water, aspirin, glucose) can be absorbed from the stomach, most absorption occurs after digestion in the small intestine.
98
98. Which of the following is NOT a function of the mucosa of the small intestine?
A. Protection against infectious disease
B. Secretion of digestive enzymes
C. The absorption of end products of digestion
D. Segmentation
Answer is D: Segmentation is caused by the muscularis externa, not the mucosa.
99
99. Which fluid within the body is likely to have the HIGHEST pH?
A. The contents of the ileum
B. The contents of the start of the duodenum
C. The blood
D. The contents of the stomach
Answer is A: Highest pH means the most alkaline. Blood pH is about 7.4, which is less than in the intestines. The proximal part of the duodenum will receive acidic chyme from the stomach, so its pH will be lowered by that. A is the best choice.
100
100. What stomach enzyme digests protein to polypeptides?
A. Pepsin
B. Hydrochloric acid
C. Gastrin
D. Intrinsic factor
Answer is A: Pepsin is the only enzyme in the list.
101
101. What are the products of protein digestion?
A. Polypeptides
B. Monosaccharides
C. Amino acids
D. Free fatty acids and monoglycerides
Answer is C: Polypeptides have not yet completed the digestion process.
102
102. Which one of the following is a function of the liver?
A. Lipase
B. Digestive enzymes
C. Insulin
D. Plasma proteins
Answer is D: Plasma proteins (albumins, globulins and fibrinogen) are produced in the liver.
103
103. A function of the LARGE intestine is to:
A. Absorb the products of digestion
B. Absorb water
C. Participate in mechanical digestion
D. Release intestinal gastrin
Answer is B: The products of digestion have been absorbed before the remaining contents reach the LI. It absorbs additional water to make faeces a paste.
104
104. Which fluid within the body is likely to have the LOWEST pH?
A. The contents of the ilium
B. The contents of the start of the duodenum
C. Urine in the bladder
D. The contents of the stomach
Answer is D: Lowest pH means most acidic. The stomach contents are most acidic.
105
105. Which of the following organs is an accessory organ rather than an organ of the gastrointestinal tract?
A. Duodenum
B. Rectum
C. Caecum
D. Liver
Answer is D: The liver is not part of the digestive tract (chyme does not pass through it); rather, it contributes bile to the gut contents via the common bile duct.
106
106. One of the following is NOT a function of the stomach. Which one?
A. Digestion of fats
B. Digestion of proteins C. Mechanical digestion D. Storage of food
Answer is A: The stomach produces pepsinogen which activates to pepsin which begins the digestion of protein. Fat is not significantly digested in the stomach (gas- tric lipase initiates the digestion of milk protein).
107
107. What is the name of the hormone that stimulates the stomach to secrete hydrochloric acid?
A. Gastrin
B. Intestinal gastrin
C. Secretin
D. Cholecystokinin
Answer is A: Gastrin is the best answer – where it comes from is not pertinent.
108
108. Which of the following pancreatic juice enzymes aids in the digestion of proteins?
A. Amylase
B. Lipase
C. Nuclease
D. Trypsin
Answer is D: Amylase digests carbohydrate; lipase digests lipids; nuclease digests nucleic acids.
109
109. What role do the Kupffer cells of the liver perform?
A. They are sinusoids.
B. They are hepatocytes.
C. They are macrophages.
D. They deaminate amino acids.
Answer is C: Kupffer cells engulf any bacteria that have travelled from the gut in the blood.
110
110. What is the process in the digestion of food molecules that produces their monomers called?
A. Polymerisation
B. Hydrolysis
C. Isomerisation
D. Deamination
Answer is B: Digestion is the process of making smaller molecules from polymers by the addition of H or OH from water. It is called hydrolysis.
111
111. Fatty acids are transported around the body by the blood in structures known as:
A. Micelles
B. Chylomicrons
C. Triglycerols
D. Low-density lipoproteins
Answer is B: Chylomicrons transport fats via the lymph system to the blood. Micelles exist in the lumen of the intestine.
112
112. In the digestion of food molecules, the process known as “hydrolysis” involves an enzyme and what else?
A. Splitting a molecule into two smaller molecules using a water molecule B. Splitting a molecule into two smaller molecules using hydrogen
C. The metabolism of glucose to produce water and energy
D. Splitting of triglycerols into molecules that are soluble in water
Answer is A: Hydro- refers to water; -lysis refers to splitting of a molecule.
113
113. The wall of the alimentary canal is made up of four layers (not in any order): the muscularis externa, serosa, mucosa and submucosa. Which layer absorbs the end products of digestion?
A. Submucosa
B. Muscularis externa
C. Serosa
D. Mucosa
Answer is D: The mucosa is the innermost layer so digested food must pass through it to be absorbed.
114
114. The functions of the stomach are:
A. Storage of meal, digestion of protein, mechanical digestion
B. Mechanical digestion, digestion of carbohydrate, food storage
C. Churning of chyme, digestion of fats, mechanical digestion
D. Digestion of protein, absorption of glucose, storage, mechanical
digestion
Answer is D: Choice A is not wrong, but D is better as it includes glucose, which, being a small molecule, can be absorbed through the stomach wall.
115
115. Which one of the following is NOT secreted in pancreatic juice?
A. Amylase
B. Trypsinogen
C. Pepsinogen
D. Lipase
Answer is C: Pepsinogen is secreted by the chief cells (zymogenic cells) in the gastric pits of the stomach.
116
116. What is the pH of the duodenum?
A. Highly acidic (pH between 1.5 and 3)
B. Highly alkaline (pH of 10–12)
C. Alkaline in the pH range 7.35–7.45
D. Alkaline (pH in the range 7.1–8.2)
Answer is D: The duodenum is slightly alkaline.
117
117. The process of hydrolysis may be represented by which of the following?
A. H+Cl− + Na+OH− → Na+ + Cl− + H2O
B. C12H22O11 + H2O → 2C6H12O6
C. Alanine + glycine → alanylglycine + H2O
D. Glucose → glycogenesis → glycogen
Answer is B: Hydrolysis refers to using a water molecule to split a larger molecule in smaller ones. Here a disaccharide is being split into two monosaccharide molecules.
118
118. In the stomach which cells secrete pepsinogen?
A. Parietal cells
B. Zymogenic cells
C. Kupffer cells
D. Enteroendocrine cells
Answer is B: “Zymogenic” means producing an enzyme – also known as chief cells.
119
119. Which part of the gastrointestinal tract contains three distinct layers of smooth muscle in its walls?
A. Rectum
B. Small intestine
C. Stomach
D. Oesophagus
Answer is C: The stomach uses its muscular wall to churn (mix) the contents as part of mechanical digestion.
120
120. Which digestive enzyme in pancreatic juice digests proteins?
A. Trypsin
B. Lipase
C. Pepsin
D. Amylase
Answer is A: While pepsin also digests protein, it is produced in the stomach, not the pancreas.
121
121. Which digestive enzyme in saliva breaks down starch?
A. Trypsin
B. Lipase
C. Pepsin
D. Amylase
Answer is D: Amylase is the salivary enzyme that begins digesting starch.
122
122. Which hormone is responsible for contraction of the gall bladder?
A. Secretin
B. Gastrin
C. Cholecystokinin
D. Intrinsic factor
Answer is C: One of the functions of CCK is to cause the gall bladder to contract.
123
123. All of the following statements regarding the liver are true except one, which one?
A. It can convert amino acids to glucose during periods of fasting.
B. Blood from the hepatic artery and portal vein travels away from the central vein of each lobule.
C. It contains special phagocytic cells which remove worn-out blood cells from the circulation.
D. It converts ammonia to urea.
Answer is B: Is not true. In fact blood from the hepatic artery and the hepatic portal vein mix and flow towards the central vein of a lobule.
124
124. During which phase are our gastric secretions stimulated by the sight and smell of food?
A. Gastric
B. Digestive
C. Cephalic
D. Intestinal
Answer is C: The cephalic phase refers to the thought and sight of food stimulating our secretions in preparation for food entering our stomach.
125
125. Which statement best describes the process of glycogenesis?
A. The digestion of glycogen in the diet
B. The conversion of fat into glycogen in muscle tissue
C. The conversion of glucose into glycogen in the liver
D. The conversion of glycogen into glucose in muscle tissue
Answer is C: The term glycogenesis refers to the making (-genesis) of glycogen (glyco-) from glucose. This removes glucose from the blood circulation.
126
126. Which of the following is a function of the normal flora of the large intestine?
A. To hydrolyse cellulose
B. To synthesise blood clotting proteins
C. To synthesise B vitamins and vitamin K D. To secrete intrinsic factor
Answer is C: Humans are unable to hydrolyse cellulose; blood clotting proteins are synthesised in the liver; intrinsic factor is secreted by the stomach.
127
127. Why is insulin not given as an oral drug?
A. It is too irritating to the gastrointestinal mucosa.
B. It is altered by passing through the liver.
C. It is too big a molecule to be absorbed through the plasma membrane. D. It would be digested by enzymes in the stomach.
Answer is D: Insulin is a protein so would be hydrolysed by protein-digesting enzymes in the stomach (and duodenum).
128
128. Which one of the listed molecule types is absorbed from the gut?
A. Starch
B. Monosaccharides
C. Cellulose
D. Polypeptides
Answer is B: All the other molecules are too large to be absorbed through the gut wall.
129
129. What are the products of carbohydrate digestion?
A. Free bases and pentose sugars
B. Monosaccharides
C. Cellulose and disaccharides
D. Free fatty acids and monoglycerides
Answer is B: Carbohydrates are polymers of small units called monosaccharides. Digestion (hydrolysis) frees the monosaccharides.
130
130. One of the functions of the liver is to produce:
A. Blood cells
B. Digestive enzymes
C. Insulin and glucagon D. Glycogen from glucose
Answer is D: Blood cells are produced in the bone marrow; digestive enzymes are produced in the pancreas and gut wall; the hormones insulin and glucagon are produced by the pancreas.
131
131. What is a function of the SMALL intestine? To:
A. Temporarily store ingested food
B. Absorb the products of digestion
C. Participate in mechanical digestion
D. Secrete hydrochloric acid
Answer is B: The small intestine has a very large surface area which makes it well
suited to absorbing the products of digestion.
132
132. Which of the following organs is an accessory organ of the gastrointestinal tract?
A. Jejunum
B. Appendix
C. Caecum
D. Pancreas
Answer is D: The other three are all part of the digestive tract itself.
133
133. What is the name of the hormone that inhibits the stomach from secreting gastric juice?
A. Gastrin
B. Pepsin
C. Enterogastrin
D. Cholecystokinin
Answer is D: One of the effects of CCK is to inhibit gastric secretion.
134
134. What role do the Kupffer cells of the liver perform?
A. They transport plasma proteins.
B. They perform gluconeogenesis.
C. They are macrophages.
D. They produce bile.
Answer is C: Kupffer cells are macrophages that engulf any bacteria in the sinusoids of the liver lobules transported there by the hepatic portal blood flow that may have originated from the gut.
135
135. Fatty acids are absorbed from the gut into structures known as:
A. Triglycerides
B. Sinusoids
C. Capillaries
D. Lacteals
Answer is D: Lacteals contain lymph in which digested fats are transported to rejoin the bloodstream in the vena cava via the thoracic duct.
136
136. Where is angiotensinogen produced? In the:
A. Adrenal glands
B. Liver
C. Kidney
D. Endothelial cells
Answer is B: The liver produces many proteins including this precursor to angiotensin II.
137
137. Consider a laboratory experiment that investigates the ability of an enzyme to hydrolyse protein at different pH levels. The solutions in the different test tubes are all at 37 °C and may contain distilled water, protein and enzyme and be at different pH. Which test tubes are likely to be the controls?
A. The ones containing distilled water
B. The test tubes with pepsin added
C. The test tube with a pH of 7.0
D. The ones without any added enzyme
Answer is D: Such an investigation should have one tube that contains the enzyme (e.g. pepsin) and another lacking the enzyme, with the tubes being identical in all other respects (i.e. both containing protein dissolved in distilled water at the same pH). In this case the one(s) without the enzyme is the control.
138
138. What does the hormone gastrin do?
A. Stimulates the secretion of saliva
B. Inhibits the secretion of gastric juice
C. Stimulates the secretion of hydrochloric acid
D. Stimulates the secretion of cholecystokinin
Answer is C: Gastrin stimulates the G cells of the gastric glands in the stomach wall to secrete hydrochloric acid.
139
139. In terms of the physiology of digestion, to what does the term “hydrolysis” refer? To the:
A. Use of hydrochloric acid to digest food molecules
B. Effect that hydronium ions have on the pH of a solution
C. Generation of hydrogen gas flatus in the large intestine
D. Production of two molecules from one by a reaction with water
Answer is D: The “hydro-” part of hydrolysis refers to water, while the “-lysis” part refers to the splitting of a large molecule into two smaller parts. The water molecule also splits into H+ and OH- which are attached to the two smaller fragments.
140
140. The alimentary canal has four layers. Which list below has them in correct order starting from the lumen?
A. Serosa, submucosa, mucosa, muscularis externa
B. Submucosa, mucosa, muscularis externa, serosa
C. Mucosa, submucosa, muscularis externa, serosa
D. Muscularis externa, mucosa, submucosa, serosa
Answer is C: The mucosal layer is in contact with the canal contents. The serosa is continuous with the visceral peritoneum.
141
141. What is unusual about the blood supply to the liver?
A. The pressure in the liver capillaries is higher (about 55 mmHg) than is usual for other capillaries.
B. Arterial and venous blood mix in the sinusoid capillaries.
C. Liver capillary beds are drained by an arteriole not a venule.
D. The osmolarity of blood in the liver lobules can reach 1200 mosmol/l.
Answer is B: Blood from the hepatic artery and the hepatic portal vein mix before returning to the heart via the hepatic vein. Choice A is true of the glomerular capil- laries of the kidney, while choice D occurs in the vasa recta of the kidney medulla.
142
142. Which of these processes occurs in the liver?
A. Deamination: the removal of an amine group from a molecule
B. The production of pepsinogen
C. The production and storage of insulin
D. The production and release of secretin, cholecystokinin and vasoactive
peptide
Answer is A: Deamination, and making the non-essential amino acids, occurs in the liver. Pepsinogen is produced in the stomach lining, insulin in the pancreas and choice D in the intestine.
143
143. “Emulsification” is used to describe which of the following processes?
A. The synthesis of cholesterol from acetyl CoA
B. The separation of a large fat globule into small droplets
C. The making of insoluble glycogen from individual glucose molecules
D. The activation of prolipase to lipase
Answer is B: Emulsification surrounds small droplets of fat with a coating that prevents the droplets from amalgamating into larger droplets. This provides more surface area for lipases to work on than would be the case if only larger droplets existed.
144
144. When do the nutrients in food enter the body?
A. When swallowed via the mouth or inserted intravenously
B. When food is converted to chyme in the stomach
C. When hydrolysis products are absorbed into the epithelial lining of the gut
D. When monosaccharides, amino acids and fatty acids are transformed in
the liver
Answer is C: Gut contents are outside of the body until absorbed through the mucosal lining.
145
145. When is it considered that food material is outside of the body?
A. When in extracellular fluid
B. When outside of a body cavity
C. When urinated or defecated out
D. When part of the contents of the gut
Answer is D: Food in the gut has not “entered the body” until it has been absorbed into the epithelial lining. This happens after being hydrolysed into molecules that are small enough to be absorbed. The material that is urinated or defecated out is indeed outside the body, but is not considered to be food.
146
146. Why are the contents of the stomach and intestines considered to be poten- tially dangerous to health?
A. Gut contains acid, bacteria and digestive enzymes.
B. Raw ingested food contains bacteria on its surface.
C. Food potentially contains toxins that have not yet been cleansed by passing through the liver.
D. The gut contains the poisonous products of metabolism such as urea waiting for excretion.
Answer is A: The stomach contains hydrochloric acid; the duodenum contains enzymes that will hydrolyse proteins, fats and carbohydrates; and the large intestine contains bacteria (normal flora).
147
147. Which of the following is one of the processes of mechanical digestion?
A. Stomach churning
B. Hydrolysis
C. Secretion of gastric juice
D. Enzyme activation
Answer is A: In the stomach, peristaltic waves (~3 per minute) mix the contents with gastric juice which facilitates chemical digestion. Secretion, while being mechanical, is not digestion.
