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Multiple Choice
In the context of cell signaling and capillary exchange, what is the most important force driving reabsorption at the venous end of a capillary?
A
Capillary hydrostatic pressure
B
Blood colloid osmotic pressure
C
Interstitial fluid osmotic pressure
D
Interstitial fluid hydrostatic pressure
Verified step by step guidance
1
Understand the concept of capillary exchange: Capillary exchange involves the movement of substances between the blood and interstitial fluid. This process is influenced by hydrostatic pressure and osmotic pressure, which are key forces driving filtration and reabsorption.
Define hydrostatic pressure: Hydrostatic pressure is the force exerted by a fluid against the walls of its container. In capillaries, capillary hydrostatic pressure pushes fluid out of the capillaries into the interstitial space.
Define osmotic pressure: Osmotic pressure is the force exerted by solutes (such as proteins) in a solution that draws water toward them. Blood colloid osmotic pressure is created by plasma proteins like albumin, which pull water back into the capillaries.
Analyze the forces at the venous end of the capillary: At the venous end, capillary hydrostatic pressure decreases, while blood colloid osmotic pressure remains relatively constant. This shift in pressure dynamics favors reabsorption of fluid back into the capillaries.
Conclude the most important force driving reabsorption: Blood colloid osmotic pressure is the dominant force at the venous end of the capillary, as it pulls water and solutes back into the bloodstream, counteracting the reduced hydrostatic pressure.