Edema May Occur When

Question

Edema may occur when
A) the plasma concentration of protein is reduced.
B) capillary hydrostatic pressure is elevated.
C) capillary endothelium permeability goes up.
D) the plasma concentration of protein is reduced and capillary endothelium permeability goes up.
E) the plasma concentration of protein is reduced, capillary hydrostatic pressure is elevated, and the capillary endothelium permeability goes up.

Accepted Answer

Edema is the accumulation of excess fluid in the tissues, and it can occur when there is a combination of factors that compromise the normal balance of fluid movement between the blood vessels and the surrounding tissues. The reduction of plasma protein concentration (such as albumin) reduces the oncotic pressure, which normally facilitates the return of interstitial fluid into the capillaries. When capillary hydrostatic pressure increases (due to factors such as venous congestion, arterial dilation or obstruction), more fluid is forced out of the capillaries and into the tissues. This can be exacerbated by an increase in the permeability of the capillary endothelium, which allows more plasma proteins and fluid to leak into the interstitial space. Therefore, the most comprehensive explanation is that all three factors (reduced protein concentration, elevated hydrostatic pressure, and increased capillary permeability) can contribute to edema. However, choice E is the best answer since it includes all of these options.