Updating field on access form every time a record changes

I have a form in access, tied to a number of tables.  Every time I change a record with the form (using the next record, previous record default arrows on the bottom of the form), i need to update some values on the form by doing a table lookup for those values.  Do I have to create my own "navigation" buttons to go to next/previous record to trap this event, or is there a default event I can use?

Thanks...tom