Starling forces or fluid movement due to filtration across the wall of a capillary is dependent up-on:

1. hydrostatic and oncotic pressure gradients across the capillary.
2. hydraulic (hydrostatic) in the vessel.
3. colloid osmotic pressure (COP) in the vessel.
4. colloid osmotic pressure (COP) in the tissue space.
a. 1 and 4 only
b. 1, 2, and 4
c. 2 and 3 only
d. 1, 2, 3, and 4

ANS: D
Ernst Starling was a nineteenth century British physiologist who studied fluid transport across membranes. His hypothesis states that the fluid movement due to filtration across the wall of a capillary is dependent upon both the hydrostatic and oncotic pressure gradients across the capil-lary. The driving force for fluid filtration across the wall of the capillary is determined by four separate pressures: hydraulic (hydrostatic), and colloid osmotic pressure (COP) both within the vessel and in the tissue space respectively.