The diagram shows a nephron. A nephron. W points to branch of renal artery. X points to branch of renal vein. Y points to tubular point of nephron. Z points to collecting duct.

Where is the blood first filtered?

If a small-diameter open glass tube is partially immersed in a vessel containing mercury, the surface of the mercury inside the tube will be a. lower than the mercury in the vessel, and shaped like the inside of a bowl. b. higher than the mercury in the vessel, and shaped like the inside of a bowl. c. lower than the mercury in the vessel, and shaped like the outside of an umbrella. d. higher than the mercury in the vessel, and shaped like the outside of an umbrella.