The eye

Question 1

Define the eye

Answer 1

This is a light sensitive organ that allows us to see

Question 2

What is the structure and function of the iris

Answer 2

It is a colored disc composed of muscle( circular and radial muscle) .

This changes the size of the pupil to control the amount of light that enters the eye.

Question 3

What is the structure and function of the pupil?

Answer 3

It is a hole in the iris that allows light to enter the eye.

Question 4

What is the structure and function of the conjunctiva

Answer 4

It is a thin transparent skin continuous with lining of eyelids.
It protects the cornea from scratching

Question 5

What is the structure and function of the cornea

Answer 5

This is the cup shaped , transparent front part of the sclera.

It bends light rays to focus on the retina

Question 6

What is the structure and function of the sclera

Answer 6

It is a tough, white fibrous coat.

It protects the eye

Question 7

What is the structure and function of the ciliary muscle

Answer 7

Circular ring of muscle fibers.

Alters the shape of the lens during accommodation.

Question 8

What is the function of the suspensory ligaments?

Answer 8

This attaches the ciliary body to the lens

Question 9

State what the retina does and what it contains and what they do.

Answer 9

The retina forms images at the back of the eye.
This contains light sensitive cells.

Rod cells- works well in the dark. Found at the sides of the retina. Allows us see black and white.

Cone cells- works well in light. Found at the center of the retina. Allows us see color.

Question 10

State the structure and the function of the choroid

Answer 10

Has black pigment to prevent reflection of light inside the eye.

Contains blood vessels to supply the retina with food and oxygen.

Question 11

State the structure and function of the aqueous humor.

Answer 11

Colorless fluid

It keeps the eye inflated and provides nourishment.

Question 12

Describe the fovea.

Answer 12

This is the most sensitive part of the retina. It only has come cells. Most light rays are focused here.

Question 13

Describe the blind spot

Answer 13

This is the point where the optic nerve leaves the eye

Had No light sensitive cells

Question 14

State the function of the optic nerve.

Answer 14

This takes electrical impulses from the retina and transmit it to the brain.

Question 15

State the structure and function of the lens

Answer 15

Transparent, elastic, biconvex structure

Makes fine adjustments to focus light on retina

Question 16

State the function of the vitreous humor

Answer 16

Gives the eye its shape

Question 17

State 5 ways how the eye is protected and describe them.

Answer 17

1) orbits- sockets in the skull that protects the back of the eye

2) eyelashes - trap dust near the eye

3) conjunctiva - protects the cornea from scratching

4) eyelids - close to protect eye from dust, bright light, blinking spread tears

5) tear glands - wash away dust, keeps conjunctiva moist, contains an enzyme which kills bacteria (Lysozyme)

Question 18

What happens in the eye when viewing near objects?

Answer 18

The lens thicken

Suspensory ligaments slacken

Ciliary muscle contract-
( when ciliary body shortens it grows towards lens which slackens suspensory ligaments)

Question 19

What happens in the eye when viewing distant objects?

Answer 19

Lens becomes thinner

Suspensory ligaments tighten

Ciliary muscles relax

Question 20

What is the effect of bright light on the eye?

Answer 20

Circular muscles of iris contract

Iris gets larger

Pupil size is reduced

Question 21

What is the effect of dim light on the eye?

Answer 21

Radial muscles of iris contract

Iris becomes smaller

Pupil gets bigger

Question 22

What is another name for short sight?
Describe it and how it is caused .
Also state how to correct it.

Answer 22

Another name is myopia.

This is when a person can see near objects but not distant objects.

It is caused by the eyeball being too long from front to back.

It can be corrected by using glasses with concave lens.

Question 23

What is another name for long sight?
Describe it and how it is caused .
Also state how to correct it.

Answer 23

Another name is hypermetropia.

This is when a person can see distant objects but not near objects.

It is caused by the eyeball being too short from front to back.

It can be corrected by using glasses with convex lens

Question 24

What is glaucoma caused by?
What do people see when they have it?
If not treated describe what happens.
How can it be treated?

Answer 24

Glaucoma is caused by the increase in pressure within the eye due to a blockage in the flow of aqueous humor.

It is painful and a halo is seen around objects in the visual field.

Increased pressure can damage the optic nerve which sends images to the brain therefore it can lead to permanent blindness.

Treatment - use eye drops to control pressure. Oral medication or surgery to open drainage canals ( trabecular meshwork) .