Structure of the Eye & Iris Reflex

• What is the main focus of today's video?

  The structure of the eye and the iris reflex
• What does a cross section of the eye allow us to see?


  It allows us to see the internal structures of the eye.
• What is the first structure that light hits when entering the eye?

  The cornea
• Why is the cornea transparent?


  To allow all light to pass through without obstruction.
• How does the cornea obtain oxygen?


  Oxygen diffuses into it from the outside air.
• What is the function of the cornea in relation to light?


  It refracts or bends light that passes through it.
• What is the iris?


  The colored part of the eye that controls the size of the pupil.
• What is the pupil?


  A gap in the middle of the iris that allows light to pass through.
• How does the lens differ from the cornea?


  The lens can change its shape to control light refraction.
• What is the role of the lens in the eye?


  To focus light perfectly onto the retina.
• What types of receptor cells are found in the retina?


  Cone cells and rod cells.
• What do cone cells allow us to do?


  See in color.
• Why can't we see colors in low light conditions?

  Because only rod cells are active in low light.
• What is the fovea?


  A special spot on the retina full of cone cells.
• What is the function of the optic nerve?


  To transmit impulses from the receptor cells to the brain.
• What happens to the pupil in bright light conditions?


  The pupil constricts to allow less light in.
• What is the purpose of the iris reflex?


  To protect the retina from damage due to bright light.
• What are the two types of muscles in the iris?

  Circular muscles and radial muscles.
• How do circular muscles affect the pupil in bright light?


  They contract, making the pupil smaller.
• What happens to the radial muscles when the pupil constricts?


  They relax to allow the circular muscles to contract.
• What occurs in low light conditions regarding the pupil?


  The pupil dilates to allow more light in.
• How do radial muscles function in low light?


  They contract to pull the pupil open.
• What are the main structures of the eye and their functions?

  • Cornea: Transparent, refracts light, obtains oxygen from air.
  • Iris: Colored part, controls pupil size.
  • Pupil: Gap allowing light to pass through.
  • Lens: Refracts light, changes shape for focus.
  • Retina: Contains cone and rod cells for vision.
  • Fovea: Spot for clear vision, full of cone cells.
  • Optic nerve: Transmits impulses to the brain.
• What are the processes involved in the iris reflex?


  • In bright light:
  • Pupil constricts (smaller).
  • Circular muscles contract, radial muscles relax.
  • In low light:
  • Pupil dilates (larger).
  • Circular muscles relax, radial muscles contract.