Akh
ꜣḫWhat it is
What a person becomes if everything works: ba and ka successfully reunited after death, transfigured into an effective spirit among the stars.
What it needs after death
The correct rites. It is an achieved state rather than an inherited one, and the funerary literature exists to bring it about.
What “soul” loses
That this is the goal. The akh is the outcome the whole apparatus is aimed at, and an akh could be written to: surviving Letters to the Dead ask deceased relatives to intervene in family disputes.
The other parts
Ka
kꜣThe vital essence, created at birth on Khnum's potter's wheel alongside the body, and the thing whos...
Ba
bꜣThe mobile, individual part: personality and the capacity to act, shown as a human-headed bird.
Ren
rnThe name, treated as a real component of a person rather than a label attached to one.
Sheut
šwtThe shadow, understood as a real part of a person and as something with its own presence and protect...
Ib
jbThe heart: the seat of thought, memory, will and character, and the organ that testifies at the judg...