Gallifreyan physiology

Gallifreyans, despite being visually indistinguishable from humans, have a variety of biological differences that set them apart.


 * Most of the known information of the Gallifreyans is based on the Time Lords, particularly the Doctor. Consequently, the following articles may have some inaccuracies due to these biases.

Resilience
Gallifreyans are, on the whole, extremely tough and resilient; generally speaking, they have much greater conscious control over their bodies than humans. This may be due to the third lobe of the Gallifreyan brain (DWA:Spare Parts), which is dedicated exclusively to body functions.

Gallifreyans can survive extreme cold (DW: The Seeds of Doom, 42) and extreme heat (DW: The End of the World). They can even survive the subzero temperatures and extremely low pressure of vacuum, for around 6 minutes (DW: Four to Doomsday), as well as electric shocks that would be fatal to humans. (DW: World War Three, Evolution of the Daleks). Röntgen (ionizing) radiation affects Gallifreyans so minimally that Gallifreyan children are routinely given radioactive toys in the nursery. They can, at will, absorb very high doses of Röntgen radiation, transform it into a form harmless to humans, and expel it from their bodies. (DW: Smith and Jones) Radiation of other kinds can be fatal, but even then a Gallifreyan can hold out for a while after receiving these lethal doses. (DW: Planet of the Spiders)

Gallifreyans need less sleep than humans do, and can make do with as little as an hour. (DW: The Talons of Weng-Chiang, DWN: The Highlanders)

A severely-injured Gallifreyan will generally slip into a healing coma, and devote all his or her energy to healing the injury. While in the coma, they may appear to be dead. (DW:Inferno, The Doctor's Daughter)

External appearance
Externally, Gallifreyans are identical to humans, though they tend to have a mostly Eurasian appearance. Such distinguishing features as hair and eye colour can be of any colour found among humans. (TDA: The Last Dodo)

Body temperature
Gallifreyans have an internal body temperature of about 60 degrees Fahrenheit (16 degrees Celsius). (DW: Spearhead from Space, REF: Doctor Who: The Visual Dictionary)


 * Oddly, no Humans have pointed out the differences in temperatures by touch. This might mean that this is a core temperature, whereas their skin temperature is closer to those of a Human.

Senses
Gallifreyan senses are usually vastly superior to human senses. Using taste, the Doctor was able to identify the blood type of a sample. (DW: The Christmas Invasion, NA: Bad Therapy) Gallifreyan eyes are better at seeing in the dark and can gather and enhance available light. (NA: Lucifer Rising) Gallifreyans also have extraordinary reflexes and precision timing. (DW: The End of the World, The Doctor's Daughter) They may also have additional time-related senses.

The Brain

 * For differences between Time Lord and Human brains see Time Lord anatomy. Some of these differences may also apply to the difference between the brains of Humans and ordinary Gallifreyans, as well.

Skeletal structure
Gallifreyan skeletal structure is identical to human skeletal structure, with the exception of the rib cage: Gallifreyans have 26 ribs, two more than humans. (NA: Blood Heat)

Circulatory system
Gallifreyan blood is different in composition from human blood, though similar in colour. The differences are readily apparent under a microscope. (DW: Spearhead from Space, The Invisible Enemy, Doctor Who: The TV Movie) It is highly adaptive, with regenerative properties. (TDA: The Art of Destruction) It doesn't have the same A and B types as human blood (i.e., the A and B antibodies are not present), and the extra-cellular matrix is incompatible with Earth-based life. (TDA: The Art of Destruction, DW: ''The Invisible Enemy')

Dual cardiovascular system
Gallifreyans naturally born before the time of Rassilon and Pythia had two hearts (NA: Cat's Cradle: Time's Crucible, Lungbarrow).

Oldbood Gallifreyans Loomed after the Pythia's curse of sterility emerge with a single heart and gain their second only after their first regeneration. (MA: The Man in the Velvet Mask) Those of Newblood houses spring from the Looms with two hearts from the outset. (NA: Christmas on a Rational Planet) A Gallifreyan can survive with only one heart, should the other be punctured or destroyed, though he or she would be weakened greatly. (MA: Managra, EDA: The Adventuress of Henrietta Street, DW:The Shakespeare Code) Even if all the blood was removed from one cardiovascular system, the Gallifreyan will still survive. (DW: Smith and Jones) A Gallifreyan in total cardiac arrest will need CPR on both hearts. (DW: Smith and Jones)

Gallifreyans can, with training, stop their hearts and feign death. (DW: Destiny of the Daleks) A dual cardiovascular system being more efficient, Gallifreyans typically have a resting pulse of only about 10 beats per minute. (DW: Spearhead from Space)

Respiratory system
In order to use their two hearts, Gallifryans have an advanced respiratory system. Instead of large lungs, they have a series of pulmonary tubes parallel to the lymphatic system. This makes them positively buoyant, allowing them to swim with ease. (PDA: Island of Death) They can also survive longer without much oxygen, past the point where a human would be unconscious. (DW: The Ark in Space, Smith and Jones) Despite this, Gallifreyans--especially frailer individuals--can be affected by altitude sickness. (DWN: Marco Polo)

Like most aspects of Gallifreyan physiology, the respiratory system is largely under conscious control. Gallifreyans can, at will, enter a trance state which reduces the need for oxygen. (DW: Terror of the Zygons, Four to Doomsday) Gallifreyans also had a respiratory bypass system, which allows them to survive strangulation (DW: Pyramids of Mars, NA:Human Nature (novel)).

Gallifreyans are immune to the effect of helium gas, which can make human voices sound high-pitched and squeaky. (DW: The Robots of Death)

Biochemistry
Gallifreyans can eat anything humans can. They are susceptible to the intoxicating effects of alcohol, but they can easily shrug off the effects when they must. (PDA: The Quantum Archangel, DW: The Girl in the Fireplace) As with humans, however, excessive consumption can produce a hangover. (BBCR: Slipback)

Some human medicines seem to work on Gallifreyans as well as humans: some sleep-inducing drugs or toxic gases, for example. (DW: The Brain of Morbius)  Anaesthetic gases of the type commonly administered before surgury, however, do not work well on Gallifreyans; a much greater quantity of anaesthetic must be administered, and even then it may not work completely. (DW:Doctor Who: The TV Movie) Finally, some human medicines are catastrophically toxic to Gallifreyans: a single tablet of aspirin is enough to kill an adult Gallifreyan. (DW:The Mind of Evil)

Gallifreyans are as susceptible to humans to the devastating effect of spectrox poisoning; spectrox toxaemia proceeds at roughly the same rate in both species, though a Gallifreyan, being tougher, will not succumb as quickly. (DW:The Caves of Androzani) They can counteract cyanide poisoning, given a number of ingredients (ginger beer, salt (from anchovies, as pure salt is "too salty"), walnuts) and a physical or mental shock, but only if done very soon after the cyanide is ingested. (DW:The Unicorn and the Wasp)