Structures of the Eyeball

What's the fibrous layer of the eye

The sclera and cornea

What is the sclera

white of the eye

What is the cornea

the transparent layer forming the front of the eye.

Can the fibrous layer of the eye regenerate

Yes, very well

Which part of the fibrous layer lets light enter the eye

The cornea

What are both parts of the fibrous layers covered by

Epithelia sheets

External - protects from abrasions

Deep - corneal epithelium - keeps Na+ content of eye low to increase clarity

What is contained in the vascular layer of the eye

Choroid, ciliary body, iris

Describe the choroid

Rich with blood vessels; the posterior 5/6ths of the vascular layer; contains melanocytes; has a posterior opening where the optic nerve leaves the eye and blood vessels enter

Describe each part of the ciliary body

Ciliary muscles - control lens shape

Ciliary processes - secrete humor

Ciliary zonule - ligaments that extend from processes to lens to help keeps its upright position

Where is the iris

Veteran the cornea and lens

What happens to the iris in bright light or when viewing something up close

Sphincter papillae contracts and pupil constricts

When viewing something at a distance or in dim light, the iris will

Dilator pupil law contracts and pupil dilates

What is the inner layer of the eye known as

retina

Which portion of the eye contains millions of photoreceptors that transduce light energy

The retina

What are the layers of the retina

pigmented layer and neural layer

Describe the pigmented layer of the retina

Single layer of pigmented cells; it absorbs light to prevent scattering in the eye; it acts as a phagocyte and also store vitamin A

Describe the neural layer of the retina

There are three mains neurons: photoreceptors, bipolar cells, and ganglionic cells. Signals are produced from light go from PR to BC to GC

What is the location where the optic nerve leaves the eye known as

The optic disc

Does the optic disc have any photoreceptors

No, there is a blind spot but our brain will fill in the gap

How many photoreceptors are in the neural layer

1/4 billion

What is the function of rods

vision in dim light and peripheral vision

What is the function of cones

Color vision and bright light

What is the makeup of cones in the eye

Red sensing cones - 60%

Green sensing cones - 30%

Blue sensing cones - 10%

What is the pit at the center of the back of the eye where all of the cones are

Fovea centralis

Within the fovea centralis, there is a yellow spot that is highly concentrated with cones. This is the

Macula lutea

What are cataracts

clouding of the lens of the eye

Does the eye move

All of the time, the eye flicks back and forth rapidly to let fovea capture a bigger picture

Where does the neural layer of the retina receive its blood supply

1) vessels in the choroid supply the other third (containing photoreceptors)

2) Inner 2/3rds served by the central artery and central vein of the retina