During a marathon race, a runner’s blood flow increases to 10.0 times her resting rate. Her blood’s viscosity has dropped to 95.0% of its normal value, and the blood pressure difference across the circulatory system has increased by 50.0%. By what factor has the average radii of her blood vessels increased?

As blood goes from the left ventricle through the arteries and veins of the human body, both its speed and pressure change. The arteries and arterioles can either constrict, reducing the area, or dilate, increasing the area, in response to certain conditions. Both of these changes can affect blood flow and blood pressure. An artery can also develop a permanent narrow area (stenosis) or a permanent wide area (aneurysm). Both of these changes can have significant health consequences. A patient has developed an aneurysm in the aorta, a short section where the diameter is twice the normal diameter. In the aneurysm, the speed of the blood is ______ than in the section before the aneurysm, and the pressure is _________ than in the section before the aneurysm.A. Greater, greater              B. Greater, lessC. Less, greater                   D. Less, less

The arterioles (small arteries) leading to an organ, constrict in order to decrease flow to the organ. To shut down an organ, blood flow is reduced naturally to 2.10% of its original value. By what factor did the radii of the arterioles constrict? Penguins do this when they stand on ice to reduce the blood flow to their feet.

The human ciculatory system has approximately 109 capillary vessels. Each vessel has a diameter of about 8.4 μm. Assuming cardiac output is 4.2 L/min, determine the average velocity (m/s) of blood flow through each capillary vessel.