The Anatomy and Physiology of the Eye



homeostasis of the eye-in bright light our pupil shrinks so not so much
light goes to the eye and it doesnt damage the retina. in dim light our pupil
dialates to allow more light to enter the eye.
external image pupil_2_215x166.gif

Key concepts -
1. Mapping to create an image in the brain - you can think of the eye behaving similar
to a camera. Lights enter the pupil, is focused by the lens and strikes a light sensitive detector
( which is the retina).
2. Photorecptor Cells (Rods & cones) - Light is mapped as a image on the surface of the
retina which causes the activating of a series of light sensitive cells known as rod and cones.
Rods- Theres 120 million sensitive dectectors of white light to provide night vision.
Cones- 7 million cones provide color information and sharpness of images.
- Photoreceptor cells convert the light into electrical impulses which are transmitted to the brain
via nerve fibers.
3. The Vision process for monochrome vision
- Isomerization of Retinal - first step in the monchrome vision process. After light hits the
rod cell is for the chromophore cis- retinal to isomerize to all trans- retinal . This event is best
understood as molecular orbitals, orbital energy and electron excitation.
- Protien conformational changes following retinal isomerizaztion - This step has a impo-
rtant effect on protiens in the isomerization event it causes the protiens to change their shape that
leads to the generation of a nerve impulse.
external image eye.jpg

  • Retina-the inner most layer in the eye
  • Fovea-center of the macula which gives sharpest vision
  • Macula-is located on the back of the yee in the center of the retina. gives central vision and contains the fovea
  • Optic nerve-bundle of over 1 million nerve fibers that carry visual messages from the retina to the brain
  • Vitreous gel-clear gel filling inside the eye
  • Iris-part of the eye that has color, regulates the amount of light that enters the eye
  • Cornea-focusing system
  • Pupil-opening at the center of the iris
  • Lens-clear part behind the iris that helps focus the eye