A large pharmaceutical company is conducting research on an experimental drug that affects blood flow in diseased tissue. A healthy 30-year-old man is enrolled in the trial, and patterns of normal blood flow through various tissues are studied. One of the patterns is shown in the image below: The blood flow curve was most likely obtained from tissue of which of the following?

Question

A large pharmaceutical company is conducting research on an experimental drug that affects blood flow in diseased tissue.  A healthy 30-year-old man is enrolled in the trial, and patterns of normal blood flow through various tissues are studied.  One of the patterns is shown in the image below:  The blood flow curve was most likely obtained from tissue of which of the following?

Quizplus · Accepted Answer

11ec160b_3c91_285e_9249_63d75434260d_MD0001_00 The blood flow curve shows a cyclical variation in flow during the cardiac cycle, with maximum flow occurring during diastole and minimal flow occurring during ventricular systole. This pattern is unique for the left ventricular myocardium. The great majority of blood flows through the vascular beds of the left ventricle during diastole, when the coronary vessels are not compressed by the high ventricular wall pressures created by myocardial contraction. This systolic reduction in blood flow is greatest in the subendocardial myocardium (where wall pressures are the highest), making it the region most prone to ischemia and myocardial infarction. (Choices A, B, D, E, and G) In all other organs, blood flows continuously throughout the cardiac cycle down the pressure gradient from the arterial source into the venous circulation. (Choice F) During systole, pressures in the right ventricle are much lower than in the left ventricle (only ~25 mm Hg compared to ~120 mm Hg). As a result, coronary perfusion pressure is able to overcome right ventricular wall pressure throughout the cardiac cycle, leading to relatively constant blood flow to the right ventricular myocardium. Educational objective: During ventricular systole, the coronary vessels supplying the left ventricle are compressed by the surrounding muscle. As a result, the majority of left ventricular blood flow occurs during diastole. The systolic reduction in coronary blood flow is greatest in the subendocardial region, making this portion of the left ventricle most prone to ischemia and infarction.

A Large Pharmaceutical Company Is Conducting Research on an Experimental