Cone Cells

• What is the pigment in cone cells?

  Iodopsin.
• How do the 3 types of cone cells differ?

  They all have different types of iodopsin pigment (red, green and blue) which all absorb different wavelengths of light.
• What does the coloured image we perceive depend on?

  The proportion of cone cells that are stimulated.
• Why can't we see colour in the dark?

  As iodopsin is only broken down if there is a high light intensity to produce an action potential.
• Why is high light energy needed to break down iodopsin pigment?

  As only one cone cell is connected to a bipolar cell.
• What is a bipolar cell?

  The cell that connects the receptor to the neuron.
• What is an advantage of cone cells?

  They give high visual acuity meaning the brain can distinguish between separate sources of light.
• Where are most cone cells located and why?

  Near the fovea, as it receives the highest intensity of light which cone cells only respond to.