There are four major parts to any AMA paper:
There is no required number of headings, not style.
The headings are meant to divide the text into primary and secondary parts, therefore there should be a minimum of two.
Select one type of style for the heading and used it throughout the paper.
Ex.: First heading, Bold Centered
Second heading, Bold Flush Left
In general, papers follow the IMRAD pattern:
Introduction
Methods
Results
Discussion
The abstract summarizes four main points:
Structured Abstract
Unstructured Abstract
Keywords