VisualAcuity

• Define visual acuity?


  The ability to tell apart points that are close together
• What type of photoreceptor give low visual acuity?

  Rods
• What do rods give?


  Low visual acuity
• Why do rods give low visual acuity?


  Because many rods join the same neurone, which means light from two points close together cannot be told apart
• what type of photoreceptor gives high visual acuity?


  Cones
• Why do cones give high visual acuity?


  Because cones are close together and one cone joins one neurone

  • when light from 2 points hits 2 cones, two action potentials (one from each cone) go to the brain- so you can distinguish 2 points that are close together as two separate points