Structure of the Eye

What are the functions of the cornea?

-Protects the eye -Refracts light toward the pupil of the eye.

Describe the physical features of the sclera.

-White and fibrous -Front of the sclera is the clear, bulging cornea, which acts as the window to the eye by bending light towards the pupil.

What are the functions of the sclera?

1) A protective layer 2) The white fibrous sclera also maintains the shape of the eye.

What are the four different layers the retina compromises of?

1) pigmented epithelium 2) light-sensitive cells 3) bipolar cells 4) cells of the optic nerve

What is the iris composed of (structure-wise)?

A thin circular muscle that acts as as diaphragm, controlling the size of the pupil (the opening formed by the iris allows light into the eye).

What form is the aqueous humour in?

A transparent fluid in a chamber behind the cornea.

What do the ciliary muscles do?

Alter the shape of lens.

Fovea Centralis.

Area at center of retina where cones are most dense and vision is sharpest.

Where are the ciliary muscles located?

Attached to ligaments suspended from the Dorsey and ventral ends of the lens.

Where does the pigmented epithelium lie?

Between the choroid layer and the light-sensitive cells.

When excited, the nerve message is passed from the rods and cones to where?

Bipolar cells.

What does the choroid layer contain?

Blood vessels.

What does the fovea centralis contain?

Cones very closely packed together.

Which light sensitive cells identifies color?

Cones.

Which light sensitive cells responds to high intensity light?

Cones.

What does the choroid layer do?

Contains blood vessels that nourish the retina.

Vitreous Humour

Contains cloudy, jelly-like material that maintains the shape of the the eyeball and permits light transmission to the retina.

What does the vitreous Humour contain?

Contains cloudy, jelly-like material.

Iris function.

Controls size of pupil to regulate amount of light entering the eye.

What do the lens do?

Focuses the image on the retina.

Where are the lens located?

Found in the are immediately behind the iris.

How many different layers does the retina compromise of?

Four layers.

What is the name of the tiny depression in the center of the retina?

Fovea centralis

What would happen if there were blood vessels in the cornea?

If there were blood vessels, it would cloud the transparent a cornea

Retina

Innermost layer of tissue at the back of the eye containing photoreceptors.

What is the cornea not supplied with?

It is not supplied with blood vessels. If there were blood vessels, it would cloud the transparent a cornea.

What is found immediately behind the iris?

Lens.

What kind of light does the rods respond to?

Low-intensity light.

What does the vitreous Humour do?

Maintains the shape of the the eyeball and permits light transmission to the retina.

Choroid Layer.

Middle layer of tissue in the eye that contains blood vessels that nourish the retina.

What happens when you look at an object?

Most of light rays fall on the fovea centralis.

How is oxygen absorbed into the cornea if there are no blood vessels to supply the oxygen?

Most of the oxygen is absorbed from gases dissolved in tears.

Are there any rods or cones next to the are where the retina and the optic nerve meet?

No.

Iris.

Opaque disk of tissue surrounding the pupil that regulates amount of light entering the eye.

Like all tissues, what does the cornea require?

Oxygen and nutrients.

What prevents light that enters the eye from scattering?

Pigment granules in the pigmented epithelium.

What do the pigmented granules in the pigmented epithelium do?

Prevents light that has entered the eye from scattering,

What kind of light does the cones respond to?

Require high-intensity light and identify color.

Which light sensitive cells responds to low intensity light?

Rods

Where are rods with the fovea centralis?

Rods surround the fovea.

Both rods and cones act like _________________________________.

Sensory Receptors.

Where are nutrients supplied from for the cornea?

The aqueous humour, which is a transparent fluid in a chamber behind the cornea.

What is the area where there is no rods and cones next to the optic nerve called?

The blind spot.

Where does the optic nerve carry the nerve message to?

The central nervous system (CNS)

What is the second/middle layer called?

The choroid layer.

What is the most sensitive area of the eye?

The fovea centralis

What is towards the front of the choroid layer?

The iris

Where does the bipolar cell relay the nerve message to?

The optic nerve.

Which layer is the sclera?

The outermost layer.

What is the innermost layer of the eye called?

The retina.

What are the three layers of the eye?

The sclera, the choroid layer, and the retina.

What does the vitreous Humour maintain?

The shape of the eyeball.

The eye has how many layers?

Three layers

Where does the vitreous humor move light?

To the retina.

Cornea

Transparent part of the sclera that protects the eye and refracts light toward the pupil of the eye.

How many functions does the cornea have?

Two.

How many functions does the sclera have?

Two.

How many types of light-sensitive cells are there? What are they?

Two; rods and cones.

How are rods and cones distributed in the retina?

Unevenly distributed in the retina.

The large chamber behind the lens are called the __________________________.

Vitreous Humour

Aqueous Humour

Watery liquid that protects the lens of the he and supplies the cornea with nutrients.

Blind Spot.

Where the optic nerve attaches to the retina.