Consider a capillary where the blood hydrostatic pressure is 3300 Pa at the arte- rial end and 2000 Pa at the venous end. If the difference between the osmotic pressures inside and outside the capillary is 2900 Pa, what would be the net pressure difference between the surrounding tissue and blood in the venous end of the capillary? A. 400 Pa. B. 900 Pa. C. 1300 Pa. D. 4900 Pa.
Option B. Blood hydrostatic pressure has a tendency to transport water and solutes out of the capillary, at the same time as osmotic pressure has a tendency to transport water into the capillary. Taking the outward route as positive: net pressure on the venous end is = 2000 − 2900 = −900 Pa and so is directed into the capillary.
