Vague pronouns

Hi, I have a problem regarding the use of the pronoun “its”.

Many changes occurred while she was president of the college, and they increased its educational quality as well as its effectiveness.

Why should the pronoun “its” be replaced by a possessive noun, “the college’s”? I thought it was obvious that “its” meant “the college’s”.

Despite research on the diagnosis of heart disease and the use of increasingly sophisticated technology in its treatment, the condition of coronary arteries is still difficult to assess precisely.

But, in this sentence, the pronoun “its” does not need to be replace by “heart disease’s”. Why? What’s the difference between these two sentences and the uses of “its”?

Thank you.

In your first sentence the pronoun ‘its’ is not replaced by ‘the college’s’
In your second sentence, the pronoun ‘its’ is not replaced by ‘heart disease’s’.

I’m sorry but because no replacement has been made I don’t understand your question.

Sorry I did not make my point clear.

1.The wrong sentence: Many changes occurred while she was president of the college, and they increased its educational quality.

The correct sentence: Many changes occurred while she was president of the college, and they increased the college’s educational quality.

Why should the pronoun “its” be replaced by a possessive noun, “the college’s”? I thought it was obvious that “its” meant “the college’s”.

  1. The correct sentence: Despite research on the diagnosis of heart disease and the use of increasingly sophisticated technology in its treatment, the condition of coronary arteries is still difficult to assess precisely.

But, in this sentence, the pronoun “its” does not need to be replace by “heart disease’s”. Why? What’s the difference between these two sentences and the uses of “its”?

No difference. Just the author’s choice to use the noun rather than the pronoun.