A) Since the pressure available for expansion of the arterioles is only 1mmHg, what does the surface tension need to be for the arterioles to expand to twice their resting size? Assume the arterioles at rest are spheres with a radius of 2.5x10^-5 m.
B) How does the value in (a) compare to the surface tension of blood, which is approximately 0.05N/m? What is needed to adjust the surface tension in the lungs so that breathing is possible?