ka - This is the part of you that your friends and other people see.
The outside of the mask, you as others see you. In today's terms, this might best conveyed as the mind, or conscious thought.
khat - This is your body, your flesh and blood.
That which decays, the biological flesh.
khu - This is the part of you that lives forever. It is your true soul.
A spiritual entity often mentioned in association with the ba. It was viewed as an entirely spiritual and absolutely immortal being.