Whenever the words “diagnose” or “diagnosis” are used in this chapter, they include any undertaking by any method, device, or procedure whatsoever, and whether gratuitous or not, to ascertain or establish whether a person is suffering from any physical or mental disorder. Such terms shall also include the taking of a person’s blood pressure and the use of mechanical devices or machines for the purpose of making a diagnosis and representing to such person any conclusion regarding his or her physical or mental condition. Machines or mechanical devices for measuring or ascertaining height or weight are excluded from this section.