If you want to engage in more advanced searching, try using Medical Subject Headings (MeSH). MeSH is a consistent, controlled vocabulary used by the National Library of Medicine to describe concepts in the medical field. MeSH headings are arranged in a hierarchy/tree structure starting at the topic with the broadest categories and working its way down the list through narrower topics.
MeSH is only used in PubMed and MEDLINE. Other databases use other subject headings; for example, CINAHL uses CINAHL Subject Headings that are more specific to nursing.
Watch the video below for an introduction to MeSH.