• Question: How do humans see in the dark?

    Asked by to Michael on 24 Jun 2014. This question was also asked by .
    • Photo: Michael Kelly

      Michael Kelly answered on 24 Jun 2014:

      We have a special type of sensory cell in the light sensitive layer of the eye called a rod, this cell is extremely sensitive. So sensitive that they don’t really work during the day, they are over stimulated and cannot signal much information up to the brain.
      Rods are sensitive because they are packed with a very efficient pigment that absorbs light, called rhodopsin. Rods are also very long so they hold masses of this pigment and are efficient at catching light. Also rhodopsin is very stabel so when there isn’t much light about it doesn’t send nonsense signals.

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