A 40-year-old female volunteers for an invasive study to measure her cardiac function. She has no previous cardiovascular history and takes no medications. With the test subject at rest, the following data is collected using blood tests, intravascular probes, and a closed rebreathing circuit: Blood hemoglobin concentration 14 g/dL Arterial oxygen content 0.22 mL O2/mL Arterial oxygen saturation 98% Venous oxygen content 0.17 mL O2/mL Venous oxygen saturation 78% Oxygen consumption 250 mL/min The patient's pulse is 75/min, respiratory rate is 14/ min, and blood pressure is 125/70 mm Hg. What is the cardiac output of this volunteer?
ABody surface area is required to calculate cardiac output.
BStroke volume is required to calculate cardiac output.
C250 mL/min
D5.0 L/min
E50 L/min
An investigator is studying patients with acute decompensated congestive heart failure. He takes measurements of a hormone released from atrial myocytes, as well as serial measurements of left atrial and left ventricular pressures. The investigator observes a positive correlation between left atrial pressures and the serum level of this hormone. Which of the following is most likely the mechanism of action of this hormone?
AIncreases potassium excretion at the collecting ducts
BConstricts afferent renal arteriole
CDecreases sodium reabsorption at the collecting tubules
DDecreases reabsorption of bicarbonate in the proximal convoluted tubules
EIncreases free water reabsorption from the distal tubules
A 59-year-old man with a history of congestive heart failure presents to his cardiologist for a follow-up visit. His past medical history is notable for diabetes mellitus, hypertension, and obesity. He takes metformin, glyburide, aspirin, lisinopril, and metoprolol. He has a 40 pack-year smoking history and drinks alcohol socially. His temperature is 99.1°F (37.2°C), blood pressure is 150/65 mmHg, pulse is 75/min, and respirations are 20/min. Physical examination reveals bilateral rales at the lung bases and 1+ edema in the bilateral legs. The physician decides to start the patient on an additional diuretic but warns the patient about an increased risk of breast enlargement. Which of the following is the most immediate physiologic effect of the medication in question?
ADecreased sodium reabsorption in the distal convoluted tubule
BDecreased bicarbonate reabsorption in the proximal convoluted tubule
CDecreased sodium reabsorption in the thick ascending limb
DDecreased renin enzyme activity
EDecreased sodium reabsorption in the collecting duct
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