The diagnosis of Cushing syndrome is often based on:

A. This option is incorrect because impaired sodium excretion by the kidneys does contribute to increased peripheral vascular resistance and hypertension.

B. Impaired sodium excretion by the kidneys can lead to fluid retention, which increases blood volume. This results in increased peripheral vascular resistance, a key factor in the development of hypertension.

C. Overstimulation of the parasympathetic nervous system typically causes a reduction in heart rate and vasodilation, which would generally lower blood pressure, not contribute to hypertension.

D. The renin-angiotensin-aldosterone system plays a crucial role in regulating blood pressure. Reduced secretion of renin, angiotensin, and aldosterone would not contribute to increased peripheral vascular resistance. In fact, these systems typically work to raise blood pressure when needed.

A. Chronic alveolar distention, often seen in conditions like emphysema, leads to the enlargement of the alveoli and results in a barrel-shaped chest. This is due to the loss of elasticity in the lungs, causing air trapping and an increased anterior-posterior diameter of the chest.

B. Chronic costochondritis causes inflammation of the cartilage between the ribs and sternum, leading to localized pain but not a barrel chest.

C. Smoking is a major risk factor for the development of chronic obstructive pulmonary disease (COPD), which can lead to chronic alveolar distention and a barrel chest, but smoking alone is not the direct cause of the chest shape.

D. Hypokalemia affects muscle function, including the muscles involved in respiration, but it does not directly cause a barrel chest.