Eye Anatomy and Physiology Quiz

Eye Anatomy and Physiology

• Photopigments:

  • Rods contain rhodopsin, alongside scotopsin (a glycoprotein).
  • Retinal, a component of rhodopsin, is derived from vitamin A, which itself is derived from beta-carotene.
  • Cones contain iodopsin and photopsins (erythrolabe, chlorolabe, cyanolabe).

• Lens Accommodation:

  • Viewing close objects requires a rounded lens, achieved through contraction of the ciliary muscle.
  • Viewing distant objects (farther than 20 feet) requires a flattened lens, achieved through relaxation of the ciliary muscle.

• False Statements About the Eye:

  • Photopigments bleaching and regeneration happen constantly.
  • Photoreceptors hyperpolarize to generate a visual signal.
  • Visual acuity relies solely on lens accommodation.

Eye Fluids

• Aqueous Humor:

  • Location: Anterior and posterior chambers between the cornea and lens.
  • Function: Nutrient delivery, waste removal, maintaining intraocular pressure.
  • Production: Ciliary body epithelium produces aqueous humor from blood plasma, filtering and modifying it.
  • Drainage: Trabecular meshwork and Canal of Schlemm drain it back into the bloodstream.

• Vitreous Humor:

  • Location: Posterior segment, between the lens and retina.
  • Function: Maintains eye shape, keeps retina in place, light transmission, protects retina from shock.
  • Production: Mostly produced during embryonic development, minimal after.
  • Drainage: Remains in the eye throughout life with slow changes.

Eye Physiology

• Photoreceptors (Rods and Cones):

  • Rods and cones are the photoreceptors in the retina that respond to different wavelengths of light to detect colour and light.
  • Rods respond to dim light, while cones respond to bright light.
  • Rods contain rhodopsin, while cones contain iodopsin and photopsins, detecting different colours.

• Photoreceptor Function:

  • Photoreceptors can undergo depolarization or hyperpolarization in response to light.
  • This process is crucial for signal transduction.
  • Accommodation of the eye involves the adjustment of the lens to focus images on various targets for good vision.

• Eyeball Movement:

  • Saccadic eye movements are rapid, jerky movements.

• Afterimages:

  • An afterimage is the temporary visual sensation that remains after viewing a bright image.

• Sensitivity to Light: Photopigments' sensitivity changes depending on light intensity (dim vs. bright).