Vision

1. Vision Pupil- adjustable opening in the center of the eye Iris- a ring of muscle the forms the colored portion of the eye around the pupil and controls the size of the pupil opening Lens- transparent structure behind pupil that changes shape to focus images on the retina

2. Vision

3. Vision Accommodation change in shape of lens focus near objects Retina inner surface of eye light sensitive contains rods and cones layers of neurons beginning of visual information processing

4. Vision Acuity- the sharpness of vision Nearsightedness nearby objects seen more clearly lens focuses image of distant objects in front of retina Farsightedness faraway objects seen more clearly lens focuses near objects behind retina

5. Retina’s Reaction to Light- Receptors Cones near center of retina (fovea) fine detail and color vision daylight or well-lit conditions Rods peripheral retina detect black, white and gray twilight or low light Saccades - quick eye movements

6. Retina’s Reaction to Light Bipolar cells- neurons that combine info from multiple receptors Ganglion cells – neurons that combine info from multiple bipolar cells. Optic nerve – bundle of axons of the ganglion cells that carry info from retina to brain.

7. Vision- Receptors Receptors in the Human Eye Cones Rods Number 6 million 120 million Location in retina Center Periphery Sensitivity in dim light Low High* Color sensitive? Yes No *Why pirates wore eyepatches? Arrrr…