Does higher water potential always mean hydrostatic pressure? and blood plasma q

(Original post by jazz_xox_)
Just checking that a high water potential means higher hydrostatic pressure?
I did a question asking why less proteins in the blood plasma means more tissue fluid formed- the answer was higher water potential in blood plasma means that more tissue fluid formed- is this because of a high hydrostatic pressure and a larger overall outward pressure?

Also, how would you differentiate between blood and blood plasma on a picture, and what are the different roles of blood and blood plasma in the formation of tissue fluid?

Thanks

(Original post by Jpw1097)
Water potential refers to the solute concentration, or how 'salty' the solution is, with water having the highest water potential of 0 kPa, everything else has a negative water potential. Hydrostatic pressure is the force exerted on the walls of the vessel/container, per unit area.
Tissue fluid (or interstitial fluid) is formed when plasma (minus large plasma proteins) moves out of the blood in the capillary. The amount of fluid that moves out of the capillary into the tissue depends on the hydrostatic pressure of the blood and the interstitial space, as well as the water potential of the blood plasma and the interstitial fluid. A higher hydrostatic pressure in the blood (or simply, blood pressure) causes more fluid to move out of the capillary into the tissue, and so more tissue fluid is formed. A higher hydrostatic pressure in the tissue decreases the pressure gradient across the capillary, and so less tissue fluid is formed. A higher water potential in the blood plasma (e.g. less protein) causes more fluid to leave the capillary by osmosis (fluid moves down its 'water potential gradient', and so more tissue fluid is formed - it has nothing to do with hydrostatic pressure. In fact, low protein in the blood would cause the hydrostatic pressure to decrease because more fluid is leaving the circulation and forming tissue fluid, so less fluid is in the circulation. Blood has 3 compontents: red blood cells (45%), plasma (which contains dissolved carbon dioxide and oxygen, antibodies, nutrients, ions, plasma proteins, amino acids, clotting factors, hormones, etc.) (55%), and the 'buffy coat' (~1%) which is made up of platelets and white blood cells.