The eyes

• What does a cross section of the eye allow us to see?

  Inside the eye's structure
• What is the first structure light hits when entering the eye?

  The cornea
• Why is the cornea transparent?

  To allow all light to pass through
• How does the cornea obtain oxygen?

  By diffusion from the outside air
• What is the function of the cornea?

  To refract or bend light
• What is the colored part of the eye called?

  The iris
• What does the iris control?

  The size of the pupil
• What is the pupil?

  A gap in the middle of the iris
• What is the role of the lens in the eye?

  To refract light and change shape
• How does the lens help focus light?

  By changing its shape
• What are the two types of receptor cells 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 the dark?

  Only rod cells are active
• What is the fovea?

  A spot on the retina with cone cells
• What is the function of the optic nerve?

  To transmit impulses to the brain
• What happens to the pupil in bright light conditions?

  It constricts to reduce light intake
• What is the purpose of the iris reflex?

  To protect the retina from damage
• 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 to make the pupil smaller
• What happens to radial muscles in bright light?

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

  It dilates to allow more light in
• How do radial muscles function in low light?

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

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

  • Bright light: Pupil constricts to protect retina
  • Low light: Pupil dilates to allow more light
  • Circular muscles contract in bright light
  • Radial muscles relax in bright light
  • Radial muscles contract in low light
  • Circular muscles relax in low light
• What is the process of accommodation in the eye?

  It changes the lens's refractive power
• Why do glasses help with accommodation issues?

  They provide additional refracting power
• Which parts of the eye are important for accommodation?

  The cornea and the lens
• What role do the ciliary muscles and suspensory ligaments play?

  They control the shape of the lens
• Where must light be focused in the eye?

  On the fovea of the retina
• How does the cornea contribute to vision?

  It refracts light consistently
• What happens to light rays from distant objects?

  They are almost parallel when hitting the eye
• How does the lens adjust for nearby objects?

  It becomes short and fat to refract more
• What happens to the ciliary muscle when focusing on nearby objects?

  It contracts and moves inward towards the lens
• What occurs to the suspensory ligaments when the ciliary muscle contracts?

  They slacken and become loose
• How does the lens adjust for distant objects?

  It stretches out to reduce curvature
• What is the medical term for long-sightedness?

  Hyperopia
• What is the issue with long-sightedness?

  The lens can't refract enough light
• How do glasses help long-sighted individuals?

  They contain convex lenses for extra refraction
• What is the problem with short-sightedness?

  The lens refracts light too much
• How do glasses assist short-sighted individuals?

  They contain concave lenses to reduce refraction