Anatomy of the Doctor: Part 2

      Time Lords have two hearts and a binary vascular system, which enables them to survive major accidents and many physical and temporal shocks that would kill a human being. They also have a respiratory bypass system that enables them to survive without breathing for some time.

Photo taken by: BBC America

     A new version of the Doctor is created after a biological metacrisis combines genetic information from the Doctor's severed hand and from the human Donna Noble, with energy from an abortive regeneration. Although he looks like the Tenth Doctor, this half-Time Lord and half-human creation has only one heart and is unable to regenerate.

Anatomy of the Doctor: Part 1

      Although he looks like a human being (and once claimed human ancestry on his mother's side), the Doctor is an alien being and his Time Lord physiology has many differences from our own. Physically, the Doctor is stronger, has sharper senses, and greater powers of endurance than a human being, and can cope with heat, cold, radiation and powerful forces better than humans can. There are also some differences to his internal anatomy that have confused many Earthly doctors.

Photo taken by: www.9emeart.fr

     When the Doctor's right hand is severed by a Sycorax warrior, residual regeneration energy allows him to grow another. His friend Captain Jack acquires the original, and the liquid bubbles whenever the Doctor or a product of his DNA is near. Later, after a run-in with a Dalek triggers the Doctor's regeneration process, he blasts his regeneration energy into his severed hand, healing himself without having to change appearance - but effectively using up one whole regeneration.