He has a lot of energy and a lot of life force; enough for a further eight regenerations in him yet. No doubt enough for some creatures to see him as a tasty feed and to want to gorge upon. He's had the threat of his life force being drained before and while there are some beings that can do that, the Doctor isn't human.

That doesn't mean that his emotional responses are so alien, because he is obviously concerned over Jennifer for how hastily she shouts and stops the door opening further. He takes his hand down off the door and makes a show of doing so.

"Strange is par for the course here and I've seen plenty before that. You should see the Zarbi. Giant ants, basically. I don't mind how you look," and of course he realises that she might mind and he is rambling along to try and be calming. "I'm sorry, I-- I've not heard of Wraith and you don't appear happy to be one?"