Lesson 3 - The Parts of the Eye

Question 1

Cornea

Answer 1

Front transparent surface of the eye. Arrangement of fibers made of collagen. Allows images to pass through to the deeper image-processing layers of the eyes.

Question 2

Sclera

Answer 2

The white of the eye. It provides a tough protective shell. It helps maintain shape. Where muscles that move the eyeball connect to the eyeball.

Question 3

Conjunctiva

Answer 3

Thin, mostly transparent tissue that overlays the sclera and inner parts of the eyelids. It plays a role in fighting infections and respond to allergens. Pink eye is a result of inflammation on this due to irritation or infection.

Question 4

Iris

Answer 4

The colored part of the eye. Its color is based on pigment concentration. The iris regulates the amount of light to enter by controlling the pupil.

Question 5

Pupil

Answer 5

Opening in the center of the iris where light enters the eye.

Question 6

Lens

Answer 6

Big clear eye part behind the pupil. It is comprised primarily of protein and water. Part of the focusing mechanism inside the eye. The lens it tied to focusing muscles with small string-like fibers called zonules. able to slightly change shape, therefore power in response to object distance from the eye. becomes less flexible past the age of 40.

Question 7

Vitreous

Answer 7

Fluid inside of the eye. Creates constant pressure inside the eye, which helps maintain the eye’s shape and holds the tissues inside the eye in place. Attached to the retina. Composed mostly of water but has a gel-like consistency. Clumping can cause a person to see floaters. To keep the eye healthy, this takes in nutrients from the ciliary body, aqueous humor, and the retinal vessels.

Question 8

Retina

Answer 8

Responsible for capturing and processing images. It is the tissue lining the inside of the eye and contains millions of photoreceptors (light-sensitive cells) that respond when stimulated by an image.

Question 9

Peripheral retina not as sensitive to….and why

Answer 9

Peripheral retina is not as sensitive to detail, but well equipped to warn of oncoming dangers. Example oncoming traffic.

Question 10

Macula

Answer 10

Part of the retina is responsible for fine-detail vision. It is located at the center of the back of the eye. It contains a much higher concentration of photoreceptor cells than other parts of the retina.

Question 11

Optic Nerve

Answer 11

What collects the information from the retina, bundles it together, and sends it on to the occipital cortex of the brain for processing. Is responsible for everyone’s small blind spot, since there are no retinal photoreceptors on it. One of the 12 pairs of cranial nerves that extend from the brain. Contains the central retina artery and central retina vein that run to and from the eyeball, providing much of its blood supply and return.

Question 12

The final image on your retina is the result of….

Answer 12

The bending of the light rays as they travel from the object you’re viewing to the back of your eye and focus on the retina.

Question 13

Your brain does what to the image of the retina?

Answer 13

Your brain flips the image of the retina, so you see it right side up

Question 14

As light passes through your eye it…

Answer 14

bends or refracts

Question 15

list the 5 layers of the cornea and list their functions

Answer 15

1. epithelium - an outer layer that protects the cornea.
2. Bowman’s membrane- a layer of tough fibers that help protect the cornea.
3. Stroma - thickest part of the cornea, making up to 90% of its width.
4. Descemet’s (pronounced dess-a-may’s) membrane- the basement membrane that lines next to the last layer of the cornea.
5. Endothelium- Innermost layer of the cornea. It acts as a little housekeeper, mopping up and getting rid of excess water that accumulates in the cornea.

Question 16

Prefix used in words describing the cornea. What does it refer to?

Answer 16

Prefix kera- refers to the tough keratin cells in the cornea.

Question 17

Aqueous humor

Answer 17

Not actually a structure, but a fluid that sits between the cornea and the lens, supplying nutrients. Build-up can cause glaucoma, a leading cause of blindness.

Question 18

How many layers thick is the retina?

Answer 18

10

Question 19

Difference between rods and cones?

Answer 19

Both are photoreceptor cells in the retina. Rods process black and white, cones process color.

Question 20

After leaving the eyes, but before reaching the brain, the optic nerve reaches the what? What occurs here?

Answer 20

The optic nerve reaches the optic chiasm. At this location, nerve fibers from half of each retina cross over to opposite sides of the brain.

Question 21

A blind spot is part of the eye where your vision is obstructed by the what? Why does this occur?

Answer 21

A blind spot is part of the eye where your vision is obstructed by the optic nerve. This is because there are no photoreceptors at the optic nerve, so you don’t see this spot.

Question 22

How many muscles tether your eyeball to the bony socket where your eyes sit? What is this socket called? What are the muscles called?

Answer 22

There are six muscles that tether your eyeball to the bony socket where your eyes sit. The socket is called the orbit. The muscles are called extraocular muscles.

Question 23

Muscles used to open your eyes

Answer 23

Levator muscles

Question 24

Muscles used to close your eye

Answer 24

Orbicularis muscles

Question 25

You can’t increase the strength of eye muscles through exercise because eye muscles are made of what?

Answer 25

Smooth muscle

Question 26

Vision therapy strengthens what?

Answer 26

Eye-to-brain connection

Question 27

What muscles allow your eyes to work in tandem, allowing depth perception?

Answer 27

Yoked muscles

Question 28

Your eye muscles work in pairs to move your eyes. List the pairings and their functions.

Answer 28

Superior and inferior rectus muscles- move eyes up and down.
Lateral and medial rectus muscles- move eyes outward and inward.
Superior and inferior oblique muscles- move eyes in a diagonal or circular motion.

Question 29

Choroid

Answer 29

The choroid is the middle layer of tissue in the wall of the eye. It’s found between the sclera (the whites of the eyes) and the retina (the light-sensitive tissue in the back of the eye). The choroid supplies the outer retina with nutrients, and maintains the temperature and volume of the eye.

Question 30

Ciliary Body

Answer 30

The ciliary body is found behind the iris. It has three main functions: accommodation, holding the lens in place and producing aqueous fluid.

Question 31

Uvea

Answer 31

The uvea is the pigmented middle layer of the eyeball. It has three segments: the iris, the ciliary body, and the choroid. The three segments are connected and composed of similar tissue.

Question 32

Lacrimal gland

Answer 32

Contains the orbital structures for tear production and drainage

Question 33

Eyelids

Answer 33

Act as a protective covering for the eyeball while helping to keep its surface lubricated. block excess light and foreign objects.

Question 34

Eyelashes

Answer 34

Help trap debris and prevent unwanted materials from entering the eye.

Question 35

What are the layers of the eyelid?

Answer 35

The outermost layer is skin, followed by a layer of muscle and more supportive tissue, and finally by the innermost conjunctiva.

Question 36

Unlike the other portions of the eye, the cornea does not have what? What does it have?

Answer 36

The cornea does not have a blood supply; however, it does have tiny nerves which make the cornea very sensitive to pain when touched or scratched.

Question 37

The cornea shape contributes to what?

Answer 37

Near and farsightedness

Question 38

What eye structure divides the eye into two chambers? What are the chambers called?

Answer 38

The iris divides the eye into the anterior and posterior chambers. The anterior is in front of the iris and the posterior is behind the iris.

Question 39

How many muscles does the iris have? What are their functions? What controls these muscles?

Answer 39

The iris contains two sets of muscles. One set of muscles dilates the pupil so that more light can pass through the retina. The other set of muscles constricts the pupil to let less light through. The body’s central nervous system controls these muscle systems to let the appropriate amount of light in.

Question 40

What is a basic test of brain function?

Answer 40

Pupil dialation

Question 41

The cornea performs how much of the necessary bending of light rays? How much does the lens do?

Answer 41

Cornea 70%, Lens 20%

Question 42

The vitreous occupies about how much of the eye volume?

Answer 42

80% of the eye volume

Question 43

Retinal pigment epithelium

Answer 43

Lies directly beneath the retina. made of a single layer of cells that provide nutrients to the overlying rod and cone photoreceptors in the retina and keep them functioning properly.

Question 44

Bruch’s membrane

Answer 44

Under the retinal pigment epithelium. separates the retina and the retinal pigment epithelium from the choroid underneath. Prevents specialized choroid vessels from growing underneath the retina and causing vision loss.

Question 45

Orbit

Answer 45

Cavity shaped like a pyramid, with four walls and its tip facing toward the brain. It is made of seven bones, which protect the eyeball from injury. It is mostly filled with fat to provide a cushion for the eye. Includes blood vessels, muscles, and the lacrimal gland. It also includes nerves involved in vision, movement, and sensation.

Question 46

Optic canal

Answer 46

The small opening in the back of the orbit through which the optic nerve passes through on its way to the brain.

Question 47

Limbus

Answer 47

Junction between the cornea and the sclera

Question 48

Ocular adnexa

Answer 48

The ocular adnexa include the eyelids, conjunctiva, lacrimal apparatus, and orbital soft tissue.

Question 49

Tarsal plate

Answer 49

The underside of the upper eyelid