The eye

• What does a cross section of the eye show?

  It shows the internal structures of the eye
• 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?

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

  To refract or bend light
• 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 function of the lens?

  To refract light and focus it
• How does the lens change its function?

  By changing its shape
• What does the retina do?

  It contains receptor cells for vision
• 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 in low light
• 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?

  It constricts to reduce light intake
• What happens to the pupil in low light?

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

  They contract to pull the pupil open
• What is the process of the iris reflex?

  • In bright light, pupils constrict to protect retina
  • In low light, pupils dilate to allow more light
  • Controlled by circular and radial muscles
• How do the functions of cone cells and rod cells differ?

  • Cone cells:
  • Sensitive to color
  • Function well in bright light
  • Rod cells:
  • Sensitive to light intensity
  • Function well in low light
• What are the roles of the cornea, lens, and retina in vision?

  • Cornea: Refracts light and allows entry
  • Lens: Adjusts shape to focus light
  • Retina: Contains receptor cells for image processing
• What are the effects of light intensity on pupil size?

  • Bright light: Pupil constricts
  • Low light: Pupil dilates
• How do circular and radial muscles work together in the iris reflex?

  • 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?

  Cornea and lens
• What role do the ciliary muscles play in accommodation?

  They control the shape of the lens
• What is the fovea's function in the eye?

  It is the spot where light is focused
• How does the cornea contribute to vision?

  It refracts light to focus on the fovea
• What happens to light rays from distant objects?

  They are almost parallel when hitting the eye
• What shape does the lens take for nearby objects?

  Short and fat
• What happens to the ciliary muscle when focusing on nearby objects?

  It contracts inwards towards the lens
• What do the suspensory ligaments do during accommodation?

  They control the tension on the lens
• How does the lens change for distant objects?

  It stretches out to reduce curvature
• What is the difference between ciliary muscles and suspensory ligaments?

  Ciliary muscles can contract; ligaments cannot
• What is long-sightedness?

  Inability to focus on nearby objects
• How does long-sightedness affect light focus?

  Light focuses behind the retina
• What type of lenses are used to correct long-sightedness?

  Convex lenses