Ask unlimited questions for free
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
The average human gut is home to perhaps 500 to 1,000 different species of bacteria.
There are more nerve cells in one human brain than there are stars in the Milky Way.
There are more sensory neurons in the tongue than in any other part of the body.
If all the neurons in the human body were lined up, they would stretch more than 600 miles.
For a complete list of videos, visit our video library