"Oh, that. It is complicated."

And spoilers. Humm, how can she explain?

"My flesh is modelled after the idea of fully programmable matter. My Huon particles hold its form. As to blood, well I do not know."

But she can show him something interesting. She offers her wrist. "Take my pulse and then rest your hand over my heart."

She only has one heart, but if he takes her pulse he should be able to feel that she has a double pulse - indicative of a bi-vascular system.