Part of the body riddle

[puzzleking123]

I'm a part of your body. Me and my friend cannot function without each other. If I was to lose my friend I would die. Apart from that we are both everlasting. What am I?

[cupid04]

foot and mouth.

[guilliebrougues]

heart and arteries

[guilliebrougues]

you are a part of my body, you said so.

[factor-fiction]

But are the heart, arteries everlasting?
Not sure why I'm botheribng though- I think the OP has forgotten he's posted this

[factor-fiction]

Ah- I was just checking to see whether puzzleking123 had been back to update us

[JonnyBoy12]

Heart and Soul, as has been already mentioned.

[factor-fiction]

But heart and soul doesn'tsatisfy the clue. Why would a heart be 'everlasting'? I don't get it.