Liver disease can stop the liver making enough plasma protein
PHYSICS · Multi-part · Fermi University Physics · Biophysics & Medical Physics · Molecular machines, transport and bioenergetics · Molecular machines, transport and bioenergetics
Life at Thermal Energy, Ch Entropy, free energy and the forces that counting produces
Problem
Liver disease can stop the liver making enough plasma protein. The colloid osmotic pressure that protein produces then falls, while the capillary's own blood pressure does not change. Take a healthy capillary's blood pressure as falling in a straight line along its length, from 35mmHg at the arterial end to 15mmHg at the venous end, and take the healthy colloid osmotic pressure of the plasma protein, uniform along the vessel, as its measured value of 25mmHg.
((a)) A patient's plasma protein concentration has fallen to two-thirds of the healthy value. Find the new colloid osmotic pressure, and the fraction of the capillary's length, measured from the arterial end, over which fluid still filters outward rather than being reabsorbed.
((b)) Find the plasma protein concentration, as a fraction of the healthy value, below which fluid filters outward along the capillary's entire length, so that no reabsorption happens anywhere.