in the system vs. of the system

Is there any difference in the meaning and usage of in the system and of the system. For instance:

Organs in the respiratory system and Organs of the respiratory system

Components in a system and Components of a system

Which one would be more appropriate if we want to talk about the functions or roles of a system?

While both in and of might be used in the example sentences, they have different meanings, and it might not always be appropriate to use one over the other.

Generally, in means located at, and of means belonging to:

• Books in a library are located at the building.
• Books of a library belong to it, but might actually be located at the house of somebody who has borrowed them—or any number of other places.

In the same analysis, the following could be said in the case of organs and the respiratory system:

• Some of the organs of the cadaver's respiratory system were still located in its respiratory system. However, they would soon be removed for more detailed inspection, and then placed into individual storage containers.

Something similar could be done with components and a system, although it would depend on the nature of what's being described if a system's components could actually exist outside of the system itself or not.

In general, however, and barring a specific context that would recommend one preposition over another, Google Books Ngram Viewer shows that components of a system is four times as common as components in a system.