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BRS Flashcards

1
Q 
1. Which of the following substances is
released from neurons in the GI tract and
produces smooth muscle relaxation?
(A) Secretin
(B) Gastrin
(C) Cholecystokinin (CCK)
(D) Vasoactive intestinal peptide (VIP)
(E) Gastric inhibitory peptide (GIP)
A
  1. The answer is D [II C 1]. Vasoactive intestinal peptide (VIP) is a gastrointestinal (GI)
    neurocrine that causes relaxation of GI smooth muscle. For example, VIP mediates the
    relaxation response of the lower esophageal sphincter when a bolus of food approaches it,
    allowing passage of the bolus into the stomach.
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2
Q 
2. Which of the following is the site of
secretion of intrinsic factor?
(A) Gastric antrum
(B) Gastric fundus
(C) Duodenum
(D) Ileum
(E) Colon
A
  1. The answer is B [IV B 1; Table 6.3; Figure 6.7]. Intrinsic factor is secreted by the parietal cells
    of the gastric fundus (as is HCl). It is absorbed, with vitamin B12, in the ileum.
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3
Q 
3. Vibrio cholerae causes diarrhea because it
(A) increases HCO3
−
 secretory channels in
intestinal epithelial cells
(B) increases Cl−
 secretory channels in crypt
cells
(C) prevents the absorption of glucose
and causes water to be retained in the
intestinal lumen isosmotically
(D) inhibits cyclic adenosine
monophosphate (cAMP) production in
intestinal epithelial cells
(E) inhibits inositol 1,4,5-triphosphate (IP3
)
production in intestinal epithelial cells
A
  1. The answer is B [V D 4 c]. Cholera toxin activates adenylate cyclase and increases cyclic
    adenosine monophosphate (cAMP) in the intestinal crypt cells. In the crypt cells, cAMP
    activates the Cl−
    -secretory channels and produces a primary secretion of Cl−
    with Na+
    and
    H2
    O following.
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4
Q
  1. Cholecystokinin (CCK) has some gastrinlike
    properties because both CCK and gastrin
    (A) are released from G cells in the stomach
    (B) are released from I cells in the
    duodenum
    (C) are members of the secretin-homologous
    family
    (D) have five identical C-terminal amino
    acids
    (E) have 90% homology of their amino acids
A
  1. The answer is D [II A 2]. The two hormones have five identical amino acids at the C terminus.
    Biologic activity of cholecystokinin (CCK) is associated with the seven C-terminal
    amino acids, and biologic activity of gastrin is associated with the four C-terminal amino
    acids. Because this CCK heptapeptide contains the five common amino acids, it is logical
    that CCK should have some gastrin-like properties. G cells secrete gastrin. I cells secrete CCK.
    The secretin family includes glucagon.
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5
Q 
5. Which of the following is transported in
intestinal epithelial cells by a Na+
-dependent
cotransport process?
(A) Fatty acids
(B) Triglycerides
(C) Fructose
(D) Alanine
(E) Oligopeptides
A
  1. The answer is D [V A–C; Table 6.4]. Fructose is the only monosaccharide that is not
    absorbed by Na+
    -dependent cotransport; it is transported by facilitated diffusion. Amino
    acids are absorbed by Na+
    -dependent cotransport, but oligopeptides (larger peptide units)
    are not. Triglycerides are not absorbed without further digestion. The products of lipid
    digestion, such as fatty acids, are absorbed by simple diffusion.
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6
Q
  1. A 49-year-old male patient with severe
    Crohn disease has been unresponsive to
    drug therapy and undergoes ileal resection.
    After the surgery, he will have steatorrhea
    because
    (A) the liver bile acid pool increases
    (B) chylomicrons do not form in the
    intestinal lumen
    (C) micelles do not form in the intestinal
    lumen
    (D) dietary triglycerides cannot be digested
    (E) the pancreas does not secrete lipase
A
  1. The answer is C [IV D 4]. Ileal resection removes the portion of the small intestine that
    normally transports bile acids from the lumen of the gut and recirculates them to the liver.
    Because this process maintains the bile acid pool, new synthesis of bile acids is needed
    only to replace those bile acids that are lost in the feces. With ileal resection, most of the
    bile acids secreted are excreted in the feces, and the liver pool is significantly diminished.
    Bile acids are needed for micelle formation in the intestinal lumen to solubilize the
    products of lipid digestion so that they can be absorbed. Chylomicrons are formed within
    the intestinal epithelial cells and are transported to lymph vessels.
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7
Q 
7. Cholecystokinin (CCK) inhibits
(A) gastric emptying
(B) pancreatic HCO3
−
 secretion
(C) pancreatic enzyme secretion
(D) contraction of the gallbladder
(E) relaxation of the sphincter of Oddi
A
  1. The answer is A [II A 2 a; Table 6.1]. Cholecystokinin (CCK) inhibits gastric emptying and
    therefore helps to slow the delivery of food from the stomach to the intestine during
    periods of high digestive activity. CCK stimulates both functions of the exocrine pancreas—
    HCO3
    −
    secretion and digestive enzyme secretion. It also stimulates the delivery of bile from
    the gallbladder to the small intestinal lumen by causing contraction of the gallbladder
    while relaxing the sphincter of Oddi.
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8
Q 
8. Which of the following abolishes
“receptive relaxation” of the stomach?
(A) Parasympathetic stimulation
(B) Sympathetic stimulation
(C) Vagotomy
(D) Administration of gastrin
(E) Administration of vasoactive intestinal
peptide (VIP)
(F) Administration of cholecystokinin (CCK)
A
  1. The answer is C [III C 1]. “Receptive relaxation” of the orad region of the stomach is
    initiated when food enters the stomach from the esophagus. This parasympathetic
    (vagovagal) reflex is abolished by vagotomy
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9
Q 
9. Secretion of which of the following
substances is inhibited by low pH?
(A) Secretin
(B) Gastrin
(C) Cholecystokinin (CCK)
(D) Vasoactive intestinal peptide (VIP)
(E) Gastric inhibitory peptide (GIP)
A
  1. The answer is B [II A 1; Table 6.1]. Gastrin’s principal physiologic action is to increase H+
    secretion. H+
    secretion decreases the pH of the stomach contents. The decreased pH, in
    turn, inhibits further secretion of gastrin—a classic example of negative feedback.
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10
Q 
10. Which of the following is the site of
secretion of gastrin?
(A) Gastric antrum
(B) Gastric fundus
(C) Duodenum
(D) Ileum
(E) Colon
A
  1. The answer is A [II A 1 b; Table 6.3; Figure 6.7]. Gastrin is secreted by the G cells of the
    gastric antrum. HCl and intrinsic factor are secreted by the fundus.
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11
Q 
11. Micelle formation is necessary for the
intestinal absorption of
(A) glycerol
(B) galactose
(C) leucine
(D) bile acids
(E) vitamin B12
(F) vitamin D
A
  1. The answer is F [V E 1; Table 6.4]. Micelles provide a mechanism for solubilizing fat-soluble
    nutrients in the aqueous solution of the intestinal lumen until the nutrients can be brought
    into contact with and absorbed by the intestinal epithelial cells. Because vitamin D is fat
    soluble, it is absorbed in the same way as other dietary lipids. Glycerol is one product of
    lipid digestion that is water soluble and is not included in micelles. Galactose and leucine
    are absorbed by Na+
    -dependent cotransport. Although bile acids are a key ingredient
    of micelles, they are absorbed by a specific Na+
    -dependent cotransporter in the ileum.
    Vitamin B12 is water soluble; thus, its absorption does not require micelles.
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12
Q
  1. Which of the following changes occurs
    during defecation?
    (A) Internal anal sphincter is relaxed
    (B) External anal sphincter is contracted
    (C) Rectal smooth muscle is relaxed
    (D) Intra-abdominal pressure is lower than
    when at rest
    (E) Segmentation contractions predominate
A
  1. The answer is A [III E 3]. Both the internal and external anal sphincters must be relaxed
    to allow feces to be expelled from the body. Rectal smooth muscle contracts and intraabdominal
    pressure is elevated by expiring against a closed glottis (Valsalva maneuver).
    Segmentation contractions are prominent in the small intestine during digestion and
    absorption.
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13
Q 
13. Which of the following is characteristic
of saliva?
(A) Hypotonicity relative to plasma
(B) A lower HCO3
−
 concentration than plasma
(C) The presence of proteases
(D) Secretion rate that is increased by
vagotomy
(E) Modification by the salivary ductal cells
involves reabsorption of K+
 and HCO3
A
  1. The answer is A [IV A 2 a; Table 6.2]. Saliva is characterized by hypotonicity and a high
    HCO3
    −
    concentration (relative to plasma) and by the presence of α-amylase and lingual
    lipase (not proteases). The high HCO3
    −
    concentration is achieved by secretion of HCO3
    −
    into saliva by the ductal cells (not reabsorption of HCO3
    −
    ). Because control of saliva
    production is parasympathetic, it is abolished by vagotomy.
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14
Q 
14. Which of the following substances is
secreted in response to an oral glucose load?
(A) Secretin
(B) Gastrin
(C) Cholecystokinin (CCK)
(D) Vasoactive intestinal peptide (VIP)
(E) Glucose-dependent insulinotropic
peptide (GIP)
A
  1. The answer is E [II A 4; Table 6.4]. Glucose-dependent insulinotropic peptide (GIP) is the
    only gastrointestinal (GI) hormone that is released in response to all three categories of
    nutrients—fat, protein, and carbohydrate. Oral glucose releases GIP, which, in turn, causes
    the release of insulin from the endocrine pancreas. This action of GIP explains why oral
    glucose is more effective than intravenous glucose in releasing insulin.
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15
Q 
15. Which of the following is true about the
secretion from the exocrine pancreas?
(A) It has a higher Cl−
 concentration than
does plasma
(B) It is stimulated by the presence of HCO3
−
in the duodenum
(C) Pancreatic HCO3
−
 secretion is increased
by gastrin
(D) Pancreatic enzyme secretion is increased
by cholecystokinin (CCK)
(E) It is hypotonic
A
  1. The answer is D [II A 2, 3; Table 6.2]. The major anion in pancreatic secretions is HCO3
    −
    (which is found in higher concentration than in plasma), and the Cl−
    concentration is
    lower than in plasma. Pancreatic secretion is stimulated by the presence of fatty acids
    in the duodenum. Secretin (not gastrin) stimulates pancreatic HCO3
    −
    secretion, and
    cholecystokinin (CCK) stimulates pancreatic enzyme secretion. Pancreatic secretions are
    always isotonic, regardless of flow rate.
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16
Q
  1. Which of the following substances must
    be further digested before it can be absorbed
    by specific carriers in intestinal cells?
    (A) Fructose
    (B) Sucrose
    (C) Alanine
    (D) Dipeptides
    (E) Tripeptides
A
  1. The answer is B [V A, B; Table 6.4]. Only monosaccharides can be absorbed by intestinal
    epithelial cells. Disaccharides, such as sucrose, must be digested to monosaccharides
    before they are absorbed. On the other hand, proteins are hydrolyzed to amino acids,
    dipeptides, or tripeptides, and all three forms are transported into intestinal cells for
    absorption.
17
Q 
17. Slow waves in small intestinal smooth
muscle cells are
(A) action potentials
(B) phasic contractions
(C) tonic contractions
(D) oscillating resting membrane
potentials
(E) oscillating release of cholecystokinin
(CCK)
A
  1. The answer is D [III A; Figure 6.3]. Slow waves are oscillating resting membrane potentials
    of the gastrointestinal (GI) smooth muscle. The slow waves bring the membrane potential
    toward or to threshold, but are not themselves action potentials. If the membrane
    potential is brought to threshold by a slow wave, then action potentials occur, followed by
    contraction.
18
Q
  1. A 24-year-old male graduate student
    participates in a clinical research study on
    intestinal motility. Peristalsis of the small
    intestine
    (A) mixes the food bolus
    (B) is coordinated by the central nervous
    system (CNS)
    (C) involves contraction of circular smooth
    muscle behind and in front of the food
    bolus
    (D) involves contraction of circular smooth
    muscle behind the food bolus and
    relaxation of circular smooth muscle in
    front of the bolus
    (E) involves relaxation of circular
    and longitudinal smooth muscle
    simultaneously throughout the small
    intestine
A
  1. The answer is D [III D 2]. Peristalsis is contractile activity that is coordinated by the
    enteric nervous system (not the central nervous system [CNS]) and propels the intestinal
    contents forward. Normally, it takes place after sufficient mixing, digestion, and absorption
    have occurred. To propel the food bolus forward, the circular smooth muscle must
    simultaneously contract behind the bolus and relax in front of the bolus; at the same time,
    longitudinal smooth muscle relaxes (lengthens) behind the bolus and contracts (shortens)
    in front of the bolus.
19
Q 
19. A 38-year-old male patient with a
duodenal ulcer is treated successfully
with the drug cimetidine. The basis for
cimetidine's inhibition of gastric H+
secretion is that it
(A) blocks muscarinic receptors on parietal
cells
(B) blocks H2
 receptors on parietal cells
(C) increases intracellular cyclic adenosine
monophosphate (CAMP) levels
(D) blocks H+
,K+
-adenosine triphosphatase
(ATPase)
(E) enhances the action of acetylcholine
(ACh) on parietal cells
A
  1. The answer is B [IV B 3 c, d (1), 6]. Cimetidine is a reversible inhibitor of H2
    receptors on
    parietal cells and blocks H+
    secretion. Cyclic adenosine monophosphate (cAMP) (the
    second messenger for histamine) levels would be expected to decrease, not increase.
    Cimetidine also blocks the action of acetylcholine (ACh) to stimulate H+
    secretion.
    Omeprazole blocks H+
    , K+
    -adenosine triphosphatase (ATPase) directly
20
Q 
20. Which of the following substances
inhibits gastric emptying?
(A) Secretin
(B) Gastrin
(C) Cholecystokinin (CCK)
(D) Vasoactive intestinal peptide (VIP)
(E) Gastric inhibitory peptide (GIP)
A
  1. The answer is C [II A 2 a; Table 6.1]. Cholecystokinin (CCK) is the most important hormone
    for digestion and absorption of dietary fat. In addition to causing contraction of the
    gallbladder, it inhibits gastric emptying. As a result, chyme moves more slowly from the
    stomach to the small intestine, thus allowing more time for fat digestion and absorption.
21
Q 
21. When parietal cells are stimulated, they
secrete
(A) HCl and intrinsic factor
(B) HCl and pepsinogen
(C) HCl and HCO3
−
(D) HCO3
−
 and intrinsic factor
(E) mucus and pepsinogen
A
  1. The answer is A [IV B I; Table 6.3]. The gastric parietal cells secrete HCl and intrinsic factor.
    The chief cells secrete pepsinogen.
22
Q 
22. A 44-year-old woman is diagnosed with
Zollinger–Ellison syndrome. Which of the
following findings is consistent with the
diagnosis?
(A) Decreased serum gastrin levels
(B) Increased serum insulin levels
(C) Increased absorption of dietary
lipids
(D) Decreased parietal cell mass
(E) Peptic ulcer disease
A
  1. The answer is E [II A 1 d; V C 3 b]. Zollinger–Ellison syndrome (gastrinoma) is a tumor of
    the non–β-cell pancreas. The tumor secretes gastrin, which then circulates to the gastric
    parietal cells to produce increased H+
    secretion, peptic ulcer, and parietal cell growth
    (trophic effect of gastrin). Because the tumor does not involve the pancreatic β-cells,
    insulin levels should be unaffected. Absorption of lipids is decreased (not increased)
    because increased H+
    secretion decreases the pH of the intestinal lumen and inactivates
    pancreatic lipases.
23
Q 
23. Which of the following is the site of
Na+
–bile acid cotransport?
(A) Gastric antrum
(B) Gastric fundus
(C) Duodenum
(D) Ileum
(E) Colon
A
  1. The answer is D [IV D 4]. Bile salts are recirculated to the liver in the enterohepatic
    circulation via a Na+
    –bile acid cotransporter located in the ileum of the small intestine.

Questions (3 decks)

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