Inorganic Case

How do animals regulate the amount of solute is present in their body fluids.

Osmotic pressure->semipermeable membrane=permeable to water but not to solutes dissolved in the water.

-Water moves from left to right side to balance out the concentration of sodium chloride.

-water moves from low osmotic pressure to high osmotic pressure. Therefore where ever the concentration of solutes is larger that will drive the direction of water to move towards it.

-There is a pressure that opposes osmotic pressure which is hydrostatic pressure. As water starts to build up and get higher on the sides, the weight of the water is essentially putting the pressure back down-which is limiting how high the water can move up the water column.

Osmotic pressure is going to drive the movement of water towards where there is more solutes. Hydrostatic pressure drives water in the opposite direction (prevents water from building up to high levels because as more water builds up, there is more hydrostatic pressure that will move the water back down)

We want to find the concentration of solutes in the body fluids->we focus on the extracellular fluids (hemalymph and blood plasma). Whatever the osmotic pressure of the extracellular fluids is, the cell will usually have the exact same osmotic pressure. We are interested in how animals regulate the total amount of solutes dissolved in their extracellular fluids.