Use of "why" in spoken conversation

What's the exact term used to describe the "why" in some people's spoken English (somewhat rural or archaic by now, I suppose) as in "When I saw how much it cost, why, I knew I couldn't afford it".....or "When our family car broke down, why, we'd just walk, until we could fix it", etc....anybody recognize these? If so, why the "why"?

"Why" is an old fashioned interjection, which is used when you are surprised or have suddenly realized something:
For example:
Why, look who's here!
And I thought to myself, why, I can do that.

Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary. http://www.ldoceonline.com/dictionary/why_2