The lens is a curved piece of glass that redirects light so light beams can bounce off an object so they come forming an image.
The Flash circuit is there to make a short flash of bright light where the shutter is revealed
The Film: The light reflected off the objects in the cameras field of view comes through the lens and strikes emulsion allowing it to take pictures.
Gas Discharge tube: Moves electrons from one electron to the other
Casing: The outer casing of the camera protecting the parts inside of the camerafrom being damaged