Vitamins A and D are a specific kind of vitamins known as fat-soluble vitamins.
What this means, is that while most other vitamins are water-soluble, meaning they can be stored within water containing compartments, fat-soluble molecules can only be stored in fat or fat containing substances.
If there is very little fat stored in the body, this means there's nowhere for those fat-soluble molecules to be stored, and therefore they will not be assimilated by the body.
In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear.