Page 265: Capillary Fluid Exchange

What are Starling Forces? Starling forces are the forces that control fluid movement through capillary membrane.

What does the capillary pressure, (also known as Pc) do to the fluid? The capillary pressure pushes the fluid out of the capillary.

What does the interstitial pressure, (also known as Pi) do to the fluid? The interstitial fluid, pushes the fluid into the capillary.

What does the plasma colloid pressure, (also known as πc) do to the fluid? the plasma colloid pressure, (also known as πc) pushes fluid into the capillary.

What does the interstitial fluid colloid pressure (also known as πi) do to the fluid? the interstitial fluid colloid pressure , (also known as πi) pulls fluid out of the capillary.

So you can also think of the colloid osmotic pressure as the attraction pressure, that pulls towards it.

What is the equation of net filtration pressure? The equation of net filtration pressure:
P(net) = [(Pc-Pi) – (πc-πi)]

What is the Filtration constant, also known as the Kf? The filtration constant is the capillary permeability which is a constant.

What is the equation of the net fluid flow, also known as the Jv?
Jv = Kf X P(net)

Where is fluid building up in conditions such as edema? in conditions such as edema the fluid is collected in the interstitium.

What are some of the conditions that will lead to Edema? Edema is caused by conditions that increases the capillary pressure, this means that fluid is pushed from the capillaries to the intersitium, and this happens in conditions such as heart failure.

It also can happen when there’s decreased amount of the plasma proteins, in this conditions there’s decreased plasma oncotic pressure. This happened in conditions such as nephritic syndrome and liver failure. And what happens here is that the pull of the capillary is going down, so it’s not attracting enough fluid back into the capillary, that means there’s gonna be more fluid into the interstitium, and therefore there will be edema building up in the interstitium.

Edema can also build up in conditions which leads to increased capillary permeability, that means the Kf will increase, and this happens in conditions such as toxins, infections or in burns.

You can also have edema build up in conditions where there’s increased interstitium colloid osmotic pressure, which means that the interstitium is gonna pull more fluid out of the capillary into the interstitium. And this happens in conditions such as lymphatic blockage.