Rods & cones

• What are rods and cones classified as?

  Photoreceptors
• What do receptors detect?

  Changes in the environment
• What happens if the stimulus detected by a receptor is big enough?


  An action potential is generated
• Where are rods and cones located in the human body?

  In the retina
• What is the function of rod cells?

  They process images in black and white
• What is retinal convergence?

  Multiple rod cells connect to one bipolar cell
• What is spatial summation in the context of rod cells?

  Adding together signals from multiple rod cells
• What is the downside of retinal convergence in rod cells?

  It provides low visual acuity
• Why might you bump into objects in the dark?

  Low visual acuity from rod cells
• How many types of cone cells are there?

  Three
• What distinguishes the three types of cone cells?

  The color pigment they contain
• What is iodopsin?

  A pigment found in cone cells
• Why do we not see colors in very dark conditions?

  Not enough light energy to break down iodopsin
• How does the connection of cone cells to bipolar cells affect vision?

  It allows for high visual acuity
• What is the fovea?

  A part of the retina with high cone density
• Why is the distribution of rods and cones in the retina uneven?

  Fovea has more cones for high light intensity
• What is the blind spot in the retina?

  Area with no photoreceptors
• What is the significance of the blind spot?

  No light can be detected there
• What are the key differences between rod and cone cells?

  • Rod cells:
  • Process images in black and white
  • Function at low light intensities
  • Multiple rod cells connect to one bipolar cell
  • Provide low visual acuity

  
  

  • Cone cells:
  • Process images in color
  • Function at high light intensities
  • One cone cell connects to one bipolar cell
  • Provide high visual acuity
• How does the structure of the retina affect vision?

  • Fovea has the highest concentration of cone cells
  • Rod cells are distributed further away from the fovea
  • Rod cells allow for vision in low light but with low acuity
  • Cone cells allow for color vision with high acuity
• What pigment do rod cells contain?

  rhodopsin
• What pigment do cone cells contain?

  Iodopsin
• Why are rod cells more sensitive to low light?

  Rhodopsin breaks down easily; rods also exhibit summation, where multiple cells combine their generator potentials to reach threshold.
• What is meant by spatial summation?

  When several rod cells synapse with one bipolar neuron, combining signals to trigger an action potential in low light.
• why do cone cells give high visual acuity

  Each cone cell synapses with a separate bipolar neuron, allowing the brain to distinguish between close points of light.
• Why do rod cells give low visual acuity

  Multiple rod cells share one bipolar neuron, so light from two points cannot be distinguished.
• Where are rod cells mostly found in the retina

  In the peripheral regions
• Where are cone cells mostly found in the retina

  Concentrated at the fovea
• why can cone cells detect colour

  There are three types of cone cells, each with a different form of iodopsin sensitive to red, green, or blue light.
• what is the role of a bipolar neurone

   It transmits impulses from photoreceptors (rods/cones) to the sensory neurone (optic nerve).