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Free STEP1 Exam Braindumps (page: 54)

Page 53 of 213
PDF with 845 Questions

A 40-year-old woman complains of chronic fatigue, aching muscles, and general weakness. Physical examination reveals a modest weight gain, dry skin, and slow reflexes. Laboratory findings include TSH:
>10 mU/L (normal range 0.55 mU/L), free T4: low to normal. With of the following is the most likely Explanation: ?

  1. hyperthyroidism due to autoimmune thyroid disease
  2. hyperthyroidism due to iodine excess
  3. hyperthyroidism secondary to a hypothalamic-pituitary defect
  4. hypothyroidism due to autoimmune thyroid disease
  5. hypothyroidism secondary to a hypothalamic-pituitary defect

Answer(s): D

Explanation:

The described symptoms are typical for hypothyroidism. Aprimary thyroid gland deficiency leads to low T4 levels and high TSH levels. The most common cause of thyroid gland failure is called autoimmune thyroiditis or Hashimoto thyroiditis. It develops slowly due to persistent inflammation of the thyroid caused by the patient's own immune system. Middle-aged women are most commonly affected. The measurement of elevated TSH levels in blood is of high diagnostic value, since it helps determine even minor degrees of hypothyroidism. Correct diagnosis is critical because treatment usually continues for life, and stopping of the treatment and reevaluating the original diagnosis is often difficult. Opposite to hypothyroidism, hyperthyroidism (choices A, B, and C) presents with symptoms such as weight loss, warm moist skin, nervousness, and trembling hands. Secondary hypothyroidism (choice E) is caused by reduced TSH levels due to hypothalamic or pituitary insufficiency.



Apatient presents with long-standing emphysema. Which of the following would you expect to see in this individual?

  1. decreased physiological dead space
  2. increased FEV1/FVC
  3. increased FRC
  4. increased FVC
  5. increased lung elastic recoil

Answer(s): C

Explanation:

Destruction of lung tissue is a hallmark of emphysema. Due to this loss of elastic tissue, lung elastic recoil is decreased. Decreased elastic recoil (not increased, choice E) shifts the mechanical balance point between chest wall and lung to a higher volume--FRC is, therefore, increased. The barrel chest is characteristic of emphysema. Destruction of alveolar walls impairs gas exchange, causing an increase in physiological dead space (choice A). Tissue loss also causes a loss of radial traction with an increase in airway resistance--FVC is decreased (choice D). Emphysema is one type of chronic obstructive pulmonary disease. A decrease in the FEV1/FVC is characteristic of an obstructive disease (choice B).



A patient with newly diagnosed schizophrenia is given chlorpromazine. It is a drug that has amongst other effects moderate anticholinergic activity. As a consequence, which of the following is an expected side effect of this medication?

  1. bradycardia
  2. decreased GI sphincter tone
  3. dry mouth
  4. emptying of urinary bladder
  5. increased GI motility

Answer(s): C

Explanation:

Chlorpromazine is an antipsychotic drug with anticholinergic action (i.e., it inhibits the effects of parasympathetic stimulation). Parasympathetic stimulation causes copious secretion by nasal, lacrimal, and parotid glands. Consequently, parasympathetic blockade is leading to a dry mouth. Parasympathetic fibers slow the heart rate and anticholinergic drugs cause tachycardia rather than bradycardia (choice A).
Functions of the parasympathetic nervous system include decreasing GI sphincter tone, increasing GI motility, and increasing emptying of the rectum and urinary bladder. Parasympathetic blockade would thus cause increased GI sphincter tone (choice B), urinary retention (choice D), and decreased GI motility (choice E) leading to constipation.



A patient presents with fever (her core temperature equals 39°C, with normal core temperature equaling 3637.5°C) as well as an elevated white cell count. Which of the following statements is true regarding the patient's elevated core body temperature?

  1. Bacterial toxins act directly on skeletal muscle to increase muscle contractile activity, therebygenerating heat and elevating core temperature.
  2. Core body temperature now exceeds the hypothalamic set point temperature.
  3. Increased core body temperature is due to increased heat production by leukocytes.
  4. Increased prostaglandins have raised the hypothalamic set point temperature.
  5. The patient will be sweating in an effort to further elevate core temperature.

Answer(s): D

Explanation:

In fever, cytokines act to increase prostaglandin levels in the hypothalamus. By an undefined mechanism, prostaglandins increase the hypothalamic set point temperature. The body's heat- generating mechanisms are activated to increase core body temperature until it approaches the new set point. Core temperature will approach but not exceed the set point temperature (choice B). Sweating lowers core temperature (choice E). Though bacterial toxins can be important in the etiology of fever, they do not act directly to increase muscle heat production (choice A). Leukocytes generate cytokines, which act centrally to influence the hypothalamus (choice C). The cellular activity that is most important in heat generation is muscle contraction.






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