In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant. 
One example:  Magma rises from deep in the earth. The magma goes into volcanos. The volcanos pressure the magma upwards. The pressure causes the magma to push through the surface of the volcano. The lava cools. The lava forms new rock. New magma is pressured to the surface of the volcano. The volcano bursts through the rock the formed after the last eruption. 
Solution is here:  magma ,lava ,new rock 
Explanation: The entities are present in the process paragraph and they undergo state change. So, this is a positive example.

Now, solve this: Waste products are deposited in the blood. Blood is carried to the kidneys through the renal arteries. The kidneys contain filters inside. The filters capture the waste products. The waste is combined with water to make urine. The urine leaves the kidney and is collected in the bladder. The cleaned blood is returned to the body. 
Solution:
waste products ,blood ,water ,urine 