Take the renal artery of a healthy person.

Urine is formed by filtration of glomerular and renal capsule walls and reabsorption of renal tubules. When blood flows through the glomerulus, other substances such as water, inorganic salts, urea and glucose will be filtered into the renal capsule cavity to form protourine. When urine flows through the renal tubules, most of the water, some inorganic salts and all glucose are reabsorbed into the blood, while the rest, such as urea, some inorganic salts and water, flow out of the renal tubules to form urine. Blood is filtered by glomeruli to form urine. Because the inner walls of glomerulus and renal capsule can't filter blood cells and macromolecular proteins into the cavity of renal capsule, the difference between urine and blood is that there are no blood cells and macromolecular proteins. When urine flows through the renal tubules, all the glucose in it is absorbed.

① As can be seen from the table, there are mainly water, inorganic salts and urea in urine, so urine mainly excretes water, inorganic salts and urea.

② As can be seen from the table, the water, inorganic salts, urea and glucose in the plasma will be filtered into the renal capsule cavity to form protourine, while the protein of blood cells and macromolecules cannot pass through, indicating that the glomerulus and the renal capsule wall have a filtering effect.

③ Glucose exists in renal capsule, but not in urine, indicating that when urine flows through renal tubules, all glucose is reabsorbed into blood by renal tubules, so renal tubules have reabsorption effect.

④ Because the glomerular and renal capsule wall can not filter the protein of blood cells and macromolecules, the difference between urine and blood is that urine does not contain blood cells and macromolecular protein; When the original urine flows through the renal tubule, all the glucose in it is reabsorbed back into the blood by the renal tubule, so the urine contains no glucose compared with the original urine.

So the answer is:

① water; Urea?

2 filtering?

③ reabsorption

④ protein of blood cells and macromolecules; glucose