The volume flow rate of blood leaving the heart to circulate throughout the body is about 5 l/min for a person at rest. all this blood eventually must pass through the smallest of blood vessels, the capillaries. a typical capillary is 6 μm (micrometer) in diameter, 1 mm long, and the blood flows through it at an average speed of 1 mm/s. a. estimate the total number of capillaries in the body. b. estimate the total surface area of all the capillaries. (hint: the surface area of one capillary is a = circumference x length).