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Free STEP1 Exam Braindumps (page: 59)

Page 58 of 213
PDF with 845 Questions

A 28-year-old, 166 cm (5.45 ft) tall woman, weighing 170 kg (375 lbs) successfully underwent biliopancreatic diversion surgery, in which a portion of her stomach was removed and the remaining portion of the stomach was connected to the lower portion of the small intestine (see below figure). What is her prevalence for peptic ulcer disease and for what reason?

  1. it is higher due to inflammation caused by the surgical staples
  2. it is higher due to the loss of secretin release
  3. it is lower since chief cells were surgically resected
  4. it is lower since G cells were surgically resected
  5. it is unchanged since the surgery was successful

Answer(s): D

Explanation:

Peptic ulcers refer to areas of the stomach or duodenal lining which became eroded by stomach acid.
Stomach acid is produced by parietal cells which are stimulated by gastrin. Since gastrin-secreting G cells are primarily found in the gastric glands of the distal stomach (gastric antrum), the surgically removed stomach portion, the patient's prevalence for peptic ulcer disease is lower after the surgery, and not unchanged as stated in choice E. However, the surgery is a dramatic event and increases the risk for many GI problems, including symptoms resulting from nutritional deficiencies. Hence, the surgery is only used for morbidly obese people (the patient's body mass index is above 50), who had no success with diet and medication. Inflammation potentially triggered by the surgical staples (choice A) might trigger prostaglandin release which has a protective function of the stomach lining. Although secretin (choice B) is known to suppress gastric acid release by inhibiting gastrin release, the lower number of G cells after surgery does not make this a good choice. Chief cells (choice C) are primarily present in the proximal stomach, the portion that remains after surgery.



In patients with type 4 renal tubular acidosis (RTA) aldosterone deficiency is often a prominent finding. Distal tubular transport of which of the following ions will be affected in these patients?

  1. hydrogen and potassium in exchange for sodium
  2. hydrogen only
  3. potassium only
  4. sodium and bicarbonate
  5. sodium only

Answer(s): A

Explanation:

The RTArefers to related conditions that are disorders of urine acidification even though other renal functions are not impaired. In type 4 RTA, distal nephron dysfunction is due to either inadequate aldosterone production or aldosterone resistance resulting from intrinsic renal disease. Thus, patients develop hyperchloremic acidosis with hyperkalemia, due to impaired distal tubular secretion of both potassium and hydrogen ions. Treatment of patients is directed at controlling serum potassium. Choices B, C, D, and E are inconsistent with the known actions of aldosterone.



A patient presented with an acute abdomen including fever, marked abdominal distension, acidosis, and leukocytosis. Laparoscopy revealed that large parts of the small intestine were necrotic and as a consequence, the entire ileum of the patient was resected. It is expected that very soon after the surgery the patient will have considerable problems resulting from the malabsorption of which of the following?

  1. iron
  2. bile acids
  3. sodium
  4. vitamin
  5. protein

Answer(s): B

Explanation:

After a meal about 90 percent of the bile acids and bile salts are absorbed from the lower ileum by way of active transport. They are directed to the liver, from where they can be released again via bile into the intestine. This enterohepatic circulation of bile acids between intestine and liver is physiologically very important for normal absorption of fat and fatsoluble vitamins, and if distorted, will lead to GI and other symptoms. The quantity of iron in the body (choice A) is maintained by controlled absorption from the duodenum, not the ileum. Although sodium (choice C) is actively absorbed in theileum, there are additional absorption mechanisms available in the jejunum and in the colon. For instance, in the jejunum, sodium is absorbed by cotransport coupled with sugars and neutral amino cids, and in the colon, there are active sodium transport mechanisms as well. Hence, no immediate sodium imbalance is expected. Although vitamin (choice D), complexed with intrinsic factor, binds to a transmembrane receptor in the ileum for absorption, a large amount of vitamin (up to 5 mg) is stored in the liver. This liver storage is thought to be sufficient for 36 years so that symptoms from vitamin deficiency will be expected at a later time, but not soon after removal of the ileum.
Protein digestion (choice E) occurs in the small intestine, with absorption of amino acids primarily in the jejunum and to a lesser extent in the ileum, and with dipeptide absorption at about equal rates in these two segments. Removal of the ileum will not immediately lead to problems due to protein malabsorption.



below figure shows a gastric parietal cell with selected membrane transporters and channels. What do X, Y, and Z represent in the figure?

  1. Option A
  2. Option B
  3. Option C
  4. Option D
  5. Option E

Answer(s): A

Explanation:

Parietal cells secrete an essentially isotonic solution of pure HCl containing 150 mM and 150 mM into the gastric lumen. This is achieved by active transport of (Y) via / -ATPase in the
apical membrane that exchanges for (Z). Chloride ions are extruded passively down their
electrical gradient through --selective ion channels. They enter the cell via - exchange that takes place at the basolateral membrane. The - comes from (the product of carbonic anhydrase). None of the other choices reflect the correct ion distribution across the gastric parietal cell.






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