post_content without html

I would like to publish a new post and not have the “contents”, and the image, all combined into one field in the data store. Of course we all know this to be the “post_content” column in the “wp_posts” table. I want the image url to go into one location, and the actual text of the post to go in another. I have created 2 new fields just for these to reside, and use in a query when I need them. But I cannot find the file/php that actually makes this assembly/insert into the data store upon selecting the “Publish” button in the admin console. It has to be in here somewhere….

I have an iPhone app that is not happy with the text&html jumbo……it just wants the clean text, and a url to go get the image from.

Can someone please help me in this issue?