QUESTION: 169

High-dose glucocorticoid therapy for treatment of rheumatoid arthritis remains highly controversial. It is widely agreed that it is highly effective in controlling acute rheumatoid inflammation, but it may also result in significant adverse effects. Complications of high-dose glucocorticoid therapy include which of the following?

excessive growth in children and acromegaly in adults
hyperkalemia
hyponatremia
suppression of the hypothalamicpituitary-adrenal axis
volume depletion

Answer(s): D

Explanation:

High-dose exogenous glucocorticoids suppress the adrenal neuroendocrine axis. Patients treated for longer than 2 weeks need to be tapered off glucocorticoids slowly to avoid adrenal insufficiency. Other complications of high-dose glucocorticoids include growth suppression, not excessive growth (choice A) in children and volume overload, not volume depletion (choice E). Hyperkalemia (choice B) and hyponatremia (choice C) are observed in adrenal insufficiency due to loss of mineralocorticoid effects and are not relevant to glucocorticoid therapy.

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QUESTION: 170

A 53-year-old healthy male undergoes an exercise stress test, running on a treadmill until a maximum exertion is obtained. Which of the following statements correctly describes effects of autonomic nerve activity on the cardiovascular system in such a healthy subject?

inhibition of parasympathetic nerves decreases total peripheral resistance
inhibition of parasympathetic nerves increases heart rate
inhibition of parasympathetic nerves increases total peripheral resistance
stimulation of parasympathetic nerves decreases the strength of cardiac ventricular contractions
stimulation of sympathetic nerves decreases the strength of cardiac ventricular contractions

Answer(s): B

Explanation:

Since cardiac SA nodal cells receive tonic input from both sympathetic and parasympathetic nerves, heart rate increases whenever sympathetic firing rate increases or parasympathetic firing rate decreases. In humans, the parasympathetic innervation of ventricular muscle is negligible (choice D), and the strength of contraction increases with increasing preload and with increasing sympathetic firing rate (choice E). With few exceptions, blood vessels are not innervated by parasympathetic nerves, and there is little effect of changes in parasympathetic tone on total peripheral resistance (choices A and C).

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QUESTION: 171

Exhibit:

Please refer to the exhibit.
The majority of in the blood is carried in which of the following forms?

Answer(s): D

Explanation:

reacts with to form (carbonic acid), in a reaction catalyzed by carbonic anhydrase.
Carbonic acid then dissociates to form -. Approximately 90% of the total in the blood is carried as -. rapidly dissociates after being formed and a negligible fraction of blood is carried in this form (choice D). Some is carried bound to hemoglobin, as carbamino compounds (choice A). This is a small fraction of the total (5%). Asimilar small fraction (5%) of total remains dissolved in solution (choice B). Given that normal blood pH is near 7, essentially dissociates to form (choice C).

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QUESTION: 172

A patient with acute glomerulonephritis has a total plasma of 2.5 mmol/L and a GFR of 160 L/day. What is the estimated daily filtered load of calcium?

64 mmol/day
120 mmol/day
240 mmol/day
400 mmol/day
800 mmol/day

Answer(s): C

Explanation:

About 40% of total plasma is bound to proteins and not filtered at the glomerular basement
membrane. Therefore, the estimated daily filtered load is 1.5 mmol/L × 160 L/day = 240 mmol/day. The exact amount of free versus total depends on the blood pH: free increases during acidosis and decreases during alkalosis. None of the other choices (A, B, D, and E) reflect the correct renal calcium filtration load.

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QUESTION: 169

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QUESTION: 170

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QUESTION: 171

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QUESTION: 172

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