You will be given a definition of a task first, then some input of the task.
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.

Air enters the nose or mouth and travels through the windpipe into the lungs. The lungs have a series of smaller and finer tubes and sacs. Air reaches the smallest and finest air sacs called alveoli. Oxygen travels from the alveoli into the blood. Oxygen-rich blood is carried to the heart. Oxygen-rich blood is pumped throughout the body by the heart. Cells take in the oxygen rich blood and release carbon dioxide rich blood. The carbon dioxide rich blood travels to the lungs. Carbon dioxide travels through the throat and is exhaled.
Output:
air ,oxygen ,oxygen-rich blood, oxygen rich blood ,carbon dioxide rich blood ,carbon dioxide