Question

why do fluids leave the capillaries at the arterial end?
multiple choice
the net filtration pressure of the blood is higher at the arterial end than it is at the venous end.
the net filtration pressure of the blood is higher at the venous end than it is at the arterial end.
the net filtration pressure of the interstitial fluid is higher at the arterial end than it is at the venous end.
the net filtration pressure of the interstitial fluid is higher at the venous end than it is at the arterial end.
the osmotic pressure is higher at the arterial end than it is at the venous end.

Explanation:

Fluid movement in capillaries is driven by net filtration pressure. At the arterial end, blood pressure (hydrostatic pressure) is relatively high. The net filtration pressure of the blood (which is the balance between hydrostatic and osmotic pressures) is higher at the arterial end compared to the venous end. This higher net filtration pressure at the arterial end forces fluid out of the capillaries. The osmotic pressure (due to plasma proteins) is relatively stable along the capillary. Interstitial fluid net filtration pressure is not the main driver for fluid leaving at the arterial end as the focus is on blood - related pressures at that site for outward fluid movement.

Answer:

The net filtration pressure of the blood is higher at the arterial end than it is at the venous end.