In a mesenteric capillary bed the sympathetic nerves to the region are cut. Local metabolic activity in the surrounding tissue then increases sharply. What do the precapillary sphincters do?

At one instant in the cardiac cycle, left ventricular pressure is 46 mm Hg and rising, left atrial pressure is 7 mm Hg, aortic pressure is 79 mm Hg, and left ventricular volume is unchanged at 130 ml. Which phase is this?

A clinician hears a swishing sound that begins right after the first heart sound and is loudest in the fifth intercostal space in line with the middle of the left clavicle. What is the most likely problem?

An angiogram shows a blockage in the anterior interventricular artery close to its origin. Which region of the heart is at greatest risk?

An ECG strip shows regularly spaced P waves at 90 per minute. Only every second P wave is followed by a QRS complex, and each QRS that does appear is normal in shape. What is the most reasonable interpretation?

A trauma patient loses a significant volume of blood and mean arterial pressure falls. What happens at the carotid sinus baroreceptors, and what do the medullary centers do in response?

In an older adult, the aorta and its major branches lose much of their elastin and become stiff. Which consequence follows most directly from the loss of elastic recoil?

A papillary muscle in the left ventricle ruptures during a myocardial infarction. During the next ventricular systole, what happens?

Experiments that argue against a special flashbulb memory mechanism find that as time increases since the occurrence of the flashbulb event, participants:

Autobiographical memories are best characterized as involving which type(s) of memory content?