GI Physio Quiz - rmansour

[ArchivalUser]

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Identify each of the Questions 1 through 3 with one of the following items:

A. Enterohepatic circulation of bile salts.

B. Potentiation.

C. H+-K+ ATPase.

D. Na+-K+ ATPase.

1. The recycling of bile salts between the small intestine and the liver.

A.
B.
C.
D.
2. The enzyme responsible for active secretion of hydrogen ions by the parietal cells.

A.
B.
C.
D.
3. When the effect of two stimulants is greater than the effect of either of the stimulants alone.

A.
B.
C.
D.

Choose the Correct Answer:

4. What is the pH of the gastric lumen during a period of fasting?

A. 0.5 - 2
B. 3 - 4
C. 6 - 7
D. 7 - 8

5. Gastric parietal (oxyntic) cells secrete:

A. Intrinsic factor.
B. Gastrin.
C. Somatostatin.
D. Cholecystokinin (CCK).

6. Which of the following has the highest pH?
A. Gastric juice.
B. Hepatic/Biliary secretions.
C. Secretions of the intestinal glands.
D. Saliva.
E. Pancreatic exocrine secretions.

7. Exocrine secretions of the pancreas are increased by all of the following EXCEPT:

A. placing acid in the duodenum.
B. placing chyme high in protein in the duodenum.
C. intravenous injection of secretin.
D. intravenous injection of CCK.
E. the enterohepatic circulation of bile salt.

8. There are two hormones of major importance that control pancreatic secretions. Hormone-A is the major stimulus for the secretion of HCO3- and H2O. Hormone-B is the major stimulus for the secretion of enzymes. Which of the following choices would be the most likely candidates for Hormone-A / Hormone-B, respectively?

A. Secretin / Gastrin.
B. Cholecystokinin / Secretin.
C. Gastrin / Secretin.
D. Secretin / Cholecystokinin.
E. Cholecystokinin / Gastrin.

9. Which of the following statements is MOST correct? Bilateral section of the vagus nerve prevents gastric acid secretion in response to:

A. olfactory sensory stimulation.
B. distention of the stomach.
C. circulation gastrin.
D. the products of protein catabolism in the duodenum.
E. histamine release.

10. Which of the Following Answers to the question below is NOT CORRECT?

Secretion of acid by the stomach can be inhibited by:
A. acidification of the stomach antrium.
B. acidification of the the duodenum.
C. blocking histamine (H2) receptors.
D. inhibition of the H+-K+-ATPase.
E. inhibition of the Na+/H+ exchanger.

[ArchivalUser]

1A
2C
3B
4C or D?D
5A
6A
7E
8D
9A
10A

[ArchivalUser]

for 9 i am changing to B

[ArchivalUser]

hey zarah highest ph is gastric juice?????? should be pancreatic secretions na... most alkaline..

[ArchivalUser]

ooopsssss...sorry,pashna...i thought they meant the most acidic ph.....obviously it is pancreatic....thx for correcting me ...i need to read the q'sss carefully...

[ArchivalUser]

ANSWERS:

Q1: The recycling of bile salts between the small intestine and the liver.
A.) Enterohepatic circulation of bile salts.

Q2: The enzyme responsible for active secretion of hydrogen ions by the parietal cells.
C.) H+-K+ATPase


Q3: When the effect of two stimulants is greater than the effect of either of the stimulants alone.
B.) Potentiation.


Q4: What is the pH of the gastric lumen during a period of fasting?

B.) pH = 3 - 4
At rest, or under conditions of fasting, acid secretion is maintained at a low level by basal histamine release. Because the contents of the lumen, and therefore lumen volume, is low, the low level of acid secretion maintains the pH of the lumen relatively acidic (approx. 3-4) . The low pH acts to limit bacterial infiltration of the lower GI tract during periods of rest. A lumen pH of 1-2 can be reached under conditions where the buffer content of the lumen is low and acid secretion is activated. Lumen pH will only reach pH of 7 or above immediately after ingestion of significant amounts of acid buffers (food), or when basal acidic secretion is inhibited (H2 antagonists or H+/K+ Pump inhibitors).

Q5: Gastric parietal (oxyntic) cells secrete:
A.) Intrinsic factor.



Q6: Which of the following has the highest pH?
E.) Pancreatic exocrine secretions.
The pH of pancreatic secretions is near 8.0. The pH of the hepatic secretions, intestinal crypt cells, and saliva is approximately 7.0, while the pH of gastric secretions is as low as 1.0.

Q7: Exocrine secretions of the pancreas are increased by all of the following EXCEPT:

E.) the enterohepatic circulation of bile salts.
Acidification of the antrum below pH of 1.0 stimulates secretion of somatostatin which diffuses through a paracellular pathway to inhibit gastrin release from G cells, thereby decreasing acid secretion by the parietal cell.


Q8: There are two hormones of major importance that control pancreatic secretions. Hormone-A is the major stimulus for the secretion of HCO3- and H2O. Hormone-B is the major stimulus for the secretion of enzymes. Which of the following choices would be the most likely candidates for Hormone-A / Hormone-B, respectively?
D.) Secretin / Cholecystokinin.
Secretin is the primary stimulus for HCO3- secretion and CCK the primary stimulus for enzyme secretion from the pancreas. Gastrin can have 'CCK like' effects, but only at non-physiologically high levels.


Q9: Which of the following statements is MOST correct? Bilateral section of the vagus nerve prevents gastric secretion in response to:

A.) olfactory sensory stimulation.
It is through the parasympathetic fibers in the vagi that the brain exerts its major control over the stomach. Olfactory sensation activates central pathways that initiate acid secretion (cephalic phase) via vagal efferents. All other factors regulate gastric secretion by activating oxyntic cells via more local or direct mechanisms.


Q10: Secretion of acid by the stomach can be inhibited by:

The INCORRECT ANSWER is E.) inhibition of the Na+/H+ exchanger.
Oxyntic cells are stimulated by histamine, gastrin and acetylcholine (enteric nerves; parasympathetic) to secrete acid. The mechanism of active H+ secretion requires activity of H+/K+ ATPase and carbonic anydrase. Therefore, block of histamine receptors (H2) or H+/K+ ATPase (omeprazole) decreases secretion. Acidification of the antrum below pH of 1.0 stimulates secretion of somatostatin which inhibits gastrin release and thereby lowers stimulation of the parietal cells. Acidification of the duodenum activates local reflex loops through enteric neurons to lower acetylchoine release at the parital cell level. As such, the Na+/H+ exchanger does not play a significant role in the elaboration of HCl acid from oxyntic cells.