The casing protects internal functions and prevents the insides from getting ruined.
The gas discharge tube (The black tube in the upper left corner) conducts electrons in order to enable the flash.
The flash circuit increases light levels and makes sure that the flash is working correctly.
The lens redirects the beams of light bouncing off the object to form an image.
The shutter controls how long the film is exposed to light and protects the film.
The film records the image and ensures that it has a purpose.