physiology 4

Question 1

2. A 43-year-old man eats a meal consisting of 40 percent protein, 10 percent fat, and 50 percent carbohydrate. Thirty minutes later the man feels the urge to defecate. Which reflex results in the urge to defecate when the duodenum is stretched?
A) Duodenocolic
B) Enterogastric
C) Intestino-intestinal
D) Rectosphincteric

Answer 1

A) Duodenocolic

Question 2

4. The ileum and distal jejunum of a 34-year-old man are ruptured in an automobile accident. The entire ileum and a portion of the jejunum are resected. What is most likely to occur in this man?
   A) Atrophic gastritis
   B) Constipation
   C) Gastric ulcer
   D) Gastroesophageal reflux disease (GERD)
   E) Vitamin B12 deficiency

Answer 2

E) Vitamin B12 deficiency

Question 3

6. A 10-year-old boy consumes a cheeseburger, fries, and chocolate shake. The meal stimulates the release of several gastrointestinal hormones. The presence of fat, carbohydrate, or protein in the duodenum stimulates the release of which hormone from the duodenal mucosa?
   A) Cholecystokinin (CCK)
   B) Glucose-dependent insulinotropic peptide (GLIP)
   C) Gastrin
   D) Motilin
   E) Secretin

Answer 3

B) Glucose-dependent insulinotropic peptide (GLIP)

Question 4

7. A clinical experiment is conducted in which one group of subjects is given 50 grams of glucose intravenously and another group is given 50 grams of glucose orally. Which factor can explain why the oral glucose load is cleared from the blood at a faster rate compared with
   the intravenous glucose load?
   A) CCK-induced insulin release
   B) CCK-induced vasoactive intestinal peptide (VIP) release
   C) GLIP-induced glucagon release
   D) GLIP-induced insulin release
   E) VIP-induced GLIP release

Answer 4

D) GLIP-induced insulin release

Question 5

11. Which hormone is released by the presence of fat and protein in the small intestine and has a major effect in decreasing gastric emptying?
A) CCK
B) GLIP
C) Gastrin
D) Motilin
E) Secretin

Answer 5

A) CCK

Question 6

15. The cephalic phase of gastric secretion accounts for about 30 percent of the acid response to a meal. Which of the following can completely eliminate the cephalic phase of gastric secretion?
A) Antacids (e.g., Rolaids)
B) Antigastrin antibody
C) Atropine
D) Histamine H2 blocker
E) Vagotomy
F) Sympathectomy

Answer 6

E) Vagotomy

Question 7

Migrating motility complexes (MMCs) occur about every 90 minutes between meals and are thought to be stimulated by the gastrointestinal hormone motilin. An absence of MMCs causes an increase in which of the following?
A) Duodenal motility
B) Gastric emptying
C) Intestinal bacteria
D) Mass movements
E) Swallowing

Answer 7

C) Intestinal bacteria

Question 8

A tropical hurricane hits a Caribbean island, and the people living there are forced to drink unclean water. Within the next several days, a large number of people experience
severe diarrhea, and about half of these people die. Samples of drinking water are positive for the bacterium Vibrio cholerae. Use this information to answer Questions 19–21

19. A toxin from V. cholerae is most likely to stimulate an increase in which of the following in the epithelial cells of the crypts of Lieberkühn in these people ?
A) Cyclic adenosine monophosphate (cAMP)
B) Cyclic guanosine monophosphate (cGMP)
C) Chloride absorption
D) Sodium absorption

20. Which type of ion channel is most likely to be irreversibly opened in the intestinal epithelial cells of these people?
A) Calcium
B) Chloride
C) Magnesium
D) Potassium
E) Sodium

21. Which range best describes the life span (in days) of an intestinal enterocyte infected with V. cholerae in a person who survives?
A) 1 to 3
B) 3 to 6
C) 6 to 9
D) 9 to 12
E) 12 to 15

Answer 8

19-A) Cyclic adenosine monophosphate (cAMP)
20-B) Chloride
21-B) 3 to 6

Question 9

23. A healthy 12-year-old boy ingests a meal containing 20 percent fats, 50 percent carbohydrates, and 30 percent proteins. The gastric juice is most likely to have the lowest pH in this boy at which time after the meal (in hours)?

A) 0.5
B) 1.0
C) 2.0
D) 3.0
E) 4.0

Answer 9

E) 4.0

Question 10

Swallowing is a complex process that involves signaling between the pharynx and swallowing center in the brain stem. Which structure is critical for determining whether a bolus of food is small enough to be swallowed?
A) Epiglottis
B) Larynx
C) Palatopharyngeal folds
D) Soft palate
E) Upper esophageal sphincter

Answer 10

C) Palatopharyngeal folds

Question 11

30. A clinical study is conducted to determine the time course of gastric acid secretion and gastric pH in healthy volunteers after a meal consisting of 10 percent fat, 30 percent protein, and 60 percent carbohydrate. The results show an immediate increase in the pH of the gastric juice after the meal, which is followed several minutes later by a secondary increase in the rate of acid secretion. A decrease in which substance is most likely to facilitate the secondary increase in the rate of acid secretion in these volunteers?

A) Gastrin
B) Cholecystokinin
C) Somatostatin
D) Vasoactive intestinal peptide

Answer 11

C) Somatostatin

Question 12

32. A 34-year-old woman has a recurrent history of duodenal ulcers associated with diarrhea, steatorrhea, and hypokalemia. Her fasting gastrin level is 550 pg/ml, and basal acid secretion is 18 mmol/hour. Human secretin 
at a dose of 0.4 μg/kg of body weight is administered intravenously over 1 minute. Postinjection blood samples are collected after 1, 2, 5, 10, and 30 minutes for determination of serum gastrin concentrations. Which serum gastrin concentration is considered diagnostic 
for gastrinoma in this woman (in pg/ml)?
A) 450
B) 500
C) 550
D) 600
E) 700

Answer 12

E) 700

Question 13

39. A 68-year-old woman with hematemesis has heartburn and stomach pain. An endoscopy shows inflammation involving the gastric body and antrum as well as a small gastric ulcer. Biopsies were positive for H. pylori. H. pylori damages the gastric mucosa primarily by increasing mucosal levels of which of the 
following?
A) Ammonium
B) Bile salts
C) Gastrin
D) NSAIDs
E) Pepsin

Answer 13

A) Ammonium

Question 14

42. A physiology experiment is conducted in an anesthetized rat. The distal duodenum is opened without disturbing its blood supply, and an oxygen-recording micropipette is inserted into the tip of a villus that is submerged in inert oil. An oxygen value of 10 mm Hg is recorded. The distal duodenum at the same location
    is then treated with the vasodilator adenosine. Which value of oxygen is most likely in the tip of the villus within 2 minutes after treatment with adenosine (in mm Hg)?
    A. 0
    B. 5
    C. 7
    D. 10
    E. 12

Answer 14

E. 12

Question 15

46. The assimilation of fats includes (1) micelle formation, (2) secretion of chylomicrons, (3) emulsification 
of fat, and (4) absorption of fat by enterocytes. Which 
sequence best describes the correct temporal order of 
these events?
A) 4, 3, 2, 1
B) 3, 1, 4, 2
C) 3, 4, 1, 2
D) 2, 1, 4, 3
E) 4, 2, 1, 3
F) 2, 4, 1, 3
G) 1, 2, 3, 4
H) 1, 3, 2, 4

Answer 15

B) 3, 1, 4, 2

Question 16

48. Cystic fibrosis (CF) is an inherited disorder of the exocrine
    glands affecting children and young people. Mucus in the
    exocrine glands becomes thick and sticky and eventually
    blocks the ducts of these glands (especially in the pancreas, lungs, and liver), forming cysts. A primary disruption
    in the transfer of which ion across cell membranes occurs
    in CF, leading to decreased secretion of fluid?
    A) Calcium
    B) Chloride
    C) Phosphate
    D) Potassium
    E) Sodium

Answer 16

B) Chloride

Question 17

50. A 10-year-old boy consumes a glass of milk and two cookies. His LES and fundus relax while the food is still in the esophagus. Which substance is most likely to cause relaxation of the LES and fundus in this boy?
A. Gastrin
B. Histamine
C. Motilin
D. Nitric oxide
E. Norepinephrine

Answer 17

D. Nitric oxide

Question 18

52. Mass movements are often stimulated after a meal by distention of the stomach (gastrocolic reflex) and distention of the duodenum (duodenocolic reflex). Mass movements often lead to which of the following?
A) Bowel movements
B) Gastric movements
C) Haustrations
D) Esophageal contractions
E) Pharyngeal peristalsis

Answer 18

A) Bowel movements

Question 18

52. Mass movements are often stimulated after a meal by
    distention of the stomach (gastrocolic reflex) and distention of the duodenum (duodenocolic reflex). Mass
    movements often lead to which of the following?
    A) Bowel movements
    B) Gastric movements
    C) Haustrations
    D) Esophageal contractions
    E) Pharyngeal peristalsis

Answer 18

A) Bowel movements

Question 19

53. A 45-year-old woman with type 1 diabetes has an early
    feeling of fullness when eating. She is often nauseous
    after a meal and vomits about once each week after
    eating. Glucose-induced damage to which structure is
    most likely to explain her gastrointestinal problem?
    A) Celiac ganglia
    B) Enteric nervous system
    C) Esophagus
    D) Stomach
    E) Vagus nerve

Answer 19

E) Vagus nerve

Question 20

55. A 55-year-old man consumes a meal consisting of 20
    percent fat, 50 percent carbohydrate, and 30 percent
    protein. The following gastrointestinal hormones are
    released at various times during the next 6 hours: gastrin, secretin, motilin, glucose-dependent insulinotropic peptide, and cholecystokinin. Which structure is
    most likely to release all five hormones in this man?
    A) Antrum
    B) Colon
    C) Duodenum
    D) Esophagus
    E) Ileum

Answer 20

C) Duodenum

Question 21

56. An 89-year-old man has a cerebrovascular accident
    (stroke) in the medulla and pons that completely eliminates all vagal output to the gastrointestinal tract. Which
    function is most likely to be totally eliminated in this man?
    A) Gastric acid secretion
    B) Gastrin release
    C) Pancreatic bicarbonate secretion
    D) Primary esophageal peristalsis
    E) Secondary esophageal peristalsis
    F) None of the above

Answer 21

D) Primary esophageal peristalsis

Question 22

58. The gastric phase of gastric secretion accounts for about 60 percent of the acid response to a meal. Which substance can virtually eliminate the secretion of acid during the gastric phase?
A) Antacids (e.g., Rolaids)
B) Antigastrin antibodies
C) Atropine
D) Histamine H2 blocker
E) Proton pump inhibitor

Answer 22

E) Proton pump inhibitor

Question 23

59. A 71-year-old man with upper abdominal pain and
    blood in the stool takes NSAIDs for the pain and washes it down with whiskey. Pentagastrin administration
    produced lower than predicted levels of gastric acid secretion. Secretion of which substance is most likely to
    be diminished in this patient with gastritis?
    A) Intrinsic factor
    B) Ptyalin
    C) Rennin
    D) Saliva
    E) Trypsin

Answer 23

A) Intrinsic factor

Question 24

61. A 45-year-old woman adds high-fiber wheat and bran foods to her diet to reduce her serum cholesterol levels. She had avoided eating foods containing wheat or rye since she was a child because her mother said they would make her sick. The woman loses 25 pounds on her new diet but has frequent stomach cramps, gas, and diarrhea. She has also become weaker, finding it difficult to complete her morning walks. What is most likely to be increased in this woman? A) Blood hemoglobin concentration B) Carbohydrate absorption C) Fecal fat D) Protein absorption E) Serum calcium

Answer 24

C) Fecal fat

Question 25

62. The control of gastric acid secretion in response to a meal involves several events that take place over a 4- or 5-hour period after the meal. These events include (1) a decrease in the pH of the gastric contents, (2) an increase in the rate of acid secretion, (3) a decrease in the rate of acid secretion, and (4) an increase in the pH of the gastric contents. Which sequence best describes the correct temporal order of events over a 4-or 5-hour period after a meal? ``` A) 4, 3, 2, 1 B) 3, 1, 4, 2 C) 3, 4, 1, 2 D) 2, 1, 4, 3 E) 4, 2, 1, 3 F) 1, 2, 3, 4 G) 2, 3, 1, 4 H) 1, 3, 2, 4 ```

Answer 25

E) 4, 2, 1, 3

Question 26

63. A newborn boy does not pass meconium within 48 hours of delivery. His abdomen is distended, and he begins vomiting. A suction biopsy of a distally narrowed segment of the colon shows a lack of ganglionic nerve cells. This newborn is at risk for developing which condition? A) Achalasia B) Enterocolitis C) Halitosis D) Pancreatitis E) Peptic ulcer

Answer 26

B) Enterocolitis

Question 27

65. Which mechanism for transport of substances across the luminal cell membrane of an enterocyte is present in newborns and infants but not in adults? A) Endocytosis B) Facilitated diffusion C) Passive diffusion D) Primary active transport E) Secondary active transport

Answer 27

A) Endocytosis

Question 28

``` 67. CF is the most common cause of pancreatitis in children. Which option best explains the mechanism of CF-induced pancreatitis? A) Activation of enterokinase B) Activation of trypsin inhibitor C) Autodigestion of pancreas D) Excessive secretion of CCK E) Gallstone obstruction ```

Answer 28

C) Autodigestion of pancreas