Final answer:
Blood pressure at the arteriole end of the capillary starts at approximately 35 mm Hg and contributes to the net filtration pressure of about 10 mm Hg, driving fluid out of the capillary.
Step-by-step explanation:
The blood pressure at the arteriole end of a capillary is the pressure caused by the force of blood being pushed against the walls of the capillaries by the heart's pumping action. This pressure, known as capillary hydrostatic pressure (CHP), is quite high when blood first enters a capillary bed from the arterioles, approximately 35 mm Hg. Blood pressure continues to decrease as blood moves through the capillary, primarily due to peripheral resistance and the cross-sectional area of capillaries being greater than that of arterioles, which lowers the velocity of blood flow and reduces pressure. As the blood flows from the capillary toward the venous end, the CHP decreases to around 18 mm Hg, facilitating the reabsorption of fluid into the capillary influenced by the blood colloid osmotic pressure (BCOP), which remains constant at about 25 mm Hg. The initial net filtration pressure (NFP) close to the arterial end of the capillary is around 10 mm Hg, driving fluid out of the capillary.