IRIS, RETINA, PHOTORECEPTORS, AND CHAMBERS

IRIS

• colored portion of the eyeball 

• controls the size of the pupil based on autonomic reflexes

RETINA

Inner coat of the eyeball, Beginning of the visual pathway

Pigmented layer

• Contains melanin  

• Absorbs stray light

Photoreceptors

• Rods 

• Cones

Rods

• shades of gray in dim light 

• 120 million 

• Absent in fovea, more numerous in the periphery of the retina 

• 6-600 : 1 bipolar cell

Cones

• stimulated by brighter light; highly acute color vision

• Blue, green, red ____

• 6 million 

• Most dense in fovea centralis (area of highest visual acuity) 

• 1:1 bipolar cell higher acuity

Optic disc

no rods or cones

Anterior Cavity

• Divided into an anterior chamber and a posterior chamber by the iris (colored portion of the eyeball). 

aqueous humor

Anterior chamber are filled with ____ (a clear, watery liquid)

Posterior Cavity

Aka vitreous chamber

vitreous humor

Posterior chamber (a transparent, gelatinous substance)