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Free STEP1 Exam Braindumps (page: 53)

Page 52 of 213
PDF with 845 Questions

A healthy 27-year-old male is given a treadmill stress test. His cardiovascular values at rest and during exercise were:
When compared to rest, what was the change in his estimated mean arterial pressure?

  1. decreased by 10 mm Hg
  2. increased by 5 mm Hg
  3. increased by 25 mm Hg
  4. increased by 35 mm Hg
  5. increased by 140 mm Hg

Answer(s): B

Explanation:

True mean arterial pressure cannot be determined without a pressure transducer, which averages the systolic and diastolic pressures throughout the cardiac cycle. However, mean arterial pressure can be estimated by adding one-third of pulse pressure to the minimum diastolic pressure. At rest his mean pressure is 30/3 + 75 = 85; during exercise mean pressure is 75/3 + 65 = 90. Hence, estimated mean pressure increased by 5 mm Hg.



Normal metabolism by the body generates large quantities of acid. In spite of this, normal blood pH is a slightly alkaline 7.4. This extracellular fluid alkalinity is maintained primarily by the body's removal of which of these?

  1. ammonia
  2. carbon dioxide
  3. keto acids such a acetoacetic acid
  4. lactic acid
  5. titratable acids such as phosphoric acid

Answer(s): B

Explanation:

The vast majority of metabolic acid excretion is in the form of the volatile acid carbon dioxide which is removed via the lungs. Much smaller quantities of nonvolatile acids must be excreted in the urine.
Titratable acids, such as phosphoric acid (choice E), make up a large fraction of the acids normally excreted in the urine. When stored fats are metabolized in large quantities, such as in diabetes mellitus, keto acids such as acetoacetic acid (choice C) make up a larger portion of the renal excreted titratable acids. Likewise, when the ischemic tissues pursue anaerobic metabolism, lactic acid (choice D) makes up a larger portion of the renal excreted titratable acids. Ammonia (choice A) is not a titratable cid, but it provides a mechanism for the kidney to excrete large amounts of acid during chronic metabolic acidosis.



Which of the following persons will have a negative free-water clearance?

  1. one who begins excreting large volumes of urine with an osmolality of 100 mosm/kg H2O after severe head injury
  2. one who drinks 2 L of distilled water in 30 minutes
  3. one who is receiving lithium treatment for depression, and who develops polyuria that is unresponsive to administration ADH
  4. one with an oat cell carcinoma of the lung, who excretes urine with an osmolality of 1000 mosm/kg H2O
  5. one with neurogenic diabetes insipidus

Answer(s): D

Explanation:

A negative free-water clearance occurs when the kidney is reabsorbing more water than it is excreting into the urine and is regulated by ADH. Choice D is correct because lung cancer can cause exogenous production of ADH, which will stimulate increased renal water reabsorption and thus a negative freewater clearance. Choice A is incorrect because the decreased ADH secretion that may occur following a severe head injury will result in a positive free-water clearance. Choice B is incorrect because rapid intake of 2 L of water will inhibit ADH secretion and thus trigger a positive free-water clearance. Choice C is incorrect because the insensitivity to ADH that occurs during lithium treatment will increase water excretion and thus cause a positive free-water clearance. Choice E is incorrect because a person with neurogenic diabetes insipidus has a reduced secretion of ADH, which will cause reduced renal water reabsorption and thus a positive free-water clearance.



A 55-year-old male presents with headache and visual field changes. He is six-and-a-half feet tall and has a puffy face. His skin on hands and feet is thickened, and compared to a picture of him at age 30, his nose, ears, and jaw seem larger. His teeth are separated (diastema). He seems to sweat more and complains of bad sleep. Which of the following would provide the greatest therapeutic benefit to this patient?

  1. GHRH
  2. growth hormone
  3. insulin
  4. somatostatin
  5. thyroid hormones

Answer(s): D

Explanation:

The symptoms are consistent with acromegaly. It is a rare disease resulting from chronic exposure to growth hormone in adulthood and presents with elevated serum growth hormone levels and elevated serum IGF-1 levels. One treatment option for acromegaly is medication with somatostatin-analogues.
These synthetic forms have a longer half-life than the normal polypeptide hormone, which is also called somatotropin release inhibiting factor (SRIF). Growth hormone (choice B), growth hormone- stimulating factors such as GHRH (choice A), and thyroid hormones (choice E) are incorrect treatments. Insulin (choice C) increases bone formation and the calcium content of bone and is therefore not part of the treatment. This can easily be remembered since insulin-like growth factor 1 (IGF-1) is an important stimulator of childhood growth.






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