Sometimes, dyspepsia is a more sudden, noticeable (acute) sensation. Depending on the cause of the dyspepsia, people may have other symptoms such as a poor appetite, nausea, constipation, diarrhea, flatulence, and belching. For some people, eating makes symptoms worse. For others, eating relieves symptoms.
An X-ray machine is essentially a camera. Instead of visible light, however, it uses X-rays to expose the film. X-rays are like light in that they are electromagnetic waves, but they are more energetic so they can penetrate many materials to varying degrees.
The images produced by X-rays are due to the different absorption rates of different tissues. Calcium in bones absorbs X-rays the most, so bones look white on a film recording of the X-ray image, called a radiograph. Fat and other soft tissues absorb less, and look gray.