Final answer:
The blood is filtered in the Bowman's capsule of the kidney, which surrounds the glomerulus and is the first step in urine formation.
Step-by-step explanation:
The blood is filtered in the Bowman's capsule of the kidney. The Bowman's capsule surrounds the glomerulus, which is a network of capillaries where filtration of the blood takes place. It is the first step in the process of urine formation.