The Eye and Vision

Question 1

Constriction of the pupil is brought about by contraction of the?

Answer 1

Circular muscle of the iris

Question 2

During accommodation for near vision what happens?

Answer 2

The lens increases in curvature

Question 3

In humans, both eyes focus on only one set of objects. This is called

Answer 3

Binocular vision

Question 4

Intraocular pressure is primarily due to the

Answer 4

Aqueous humor

Question 5

Most of the refraction of light entering the eye occurs at the

Answer 5

Cornea

Question 6

The anterior cavity contains

Answer 6

Aqueous humor

Question 7

The blind spot is the area where

Answer 7

The optic nerve exits the eye

Question 8

The fibrous tunic is composed of the?

Answer 8

Sclera and cornea

Question 9

The point of greatest visual acuity is the?

Answer 9

Central fovea

Question 10

The white of the eye, which gives shape to the eyeball, makes it more rigid, and protects its inner parts is the?

Answer 10

Sclera

Question 11

When entering a dark room on a sunny day, it takes some time to be able to see because

Answer 11

It takes time for the retina to rebuild its rhodopsin

Question 12

What are the three-layers the wall of the eye is made up of?

Answer 12

The fibrous tunic (outer layer), vascular tunic (middle layer) and the retina (inner layer)

Question 13

What is the fibrous tunic made up of?

Answer 13

Cornea and sclera

Question 14

What is the function of the eye lids?

Answer 14

Shield and protect the eyeball from mechanical injury and drying out

Question 15

What is the function of the eyelashes?

Answer 15

Protect the eye from airborne dirt, dust and irritants to the eye

Question 16

What is the function of the eyebrows?

Answer 16

Protects the eye from moisture to maintain sight

Question 17

What is the function of the lacrimal apparatus?

Answer 17

Produce tears to protect the eyeball and cornea through moisture and antibodies against infection. Contains lysozyme to kill pathogens

Question 18

What is the function of the extrinsic eye muscle?

Answer 18

Control movement of the eyeball and superior palpable

Question 19

What are lysozyme?

Answer 19

A protective bactericidal enzyme, protects, cleans and lubricates the eyeball

Question 20

What are the three layers of the tunics?

Answer 20

Fibrous tunic (outer-layer)
Vascular layer (middle layer) 
Retina (inner layer)

Question 21

Structures involved with the Fibrous?

Answer 21

Sclera and Cornea

Question 22

Function of sclera?

Answer 22

Fibrous and tough and provides protection and form

Question 23

Function of Cornea?

Answer 23

Refracts 75% of light for focus

Question 24

Structures involved with the vascular?

Answer 24

Choroid, ciliary body and iris

Question 25

Function of the choroid?

Answer 25

- Blood flow in the eye, provides nutrients, oxygen and removes waste - Melanocytes which produce melanin to absorb scattered light within the eye ball and maintain sharp clear images

Question 26

Function of the ciliary body?

Answer 26

Changes shape of the lens

Question 27

Function of the iris?

Answer 27

The coloured part of the eye, which controls the amount of light entering the eye

Question 28

Describe the retina of the eye?

Answer 28

Contains photoreceptors which change light to electrochemical signals that are transmitted to CNS

Question 29

Describe rods?

Answer 29

- Only one type of rod (rhodopsin) - Rhodopsin is responsible for black and white vision - More numerous - Rod shaped

Question 30

Describe cones?

Answer 30

- 3 different types of rhodopsin - Responsible for coloured vision - Only found in the fovea centrails - Coned shaped

Question 31

What is accommodation?

Answer 31

Changing shape of the lens to allow sharp focusing of light onto the retina

Question 32

What happens when you view a near object?

Answer 32

The Ciliary muscles contract and the Lens thickens

Question 33

What is the visual pathway?

Answer 33

Optic nerve - hypothalamus - midbrain - primary visual area and association area

Question 34

Age related changes to the eye?

Answer 34

- Lens lossens - Sclera thickens and changes colour - Iris fades and develops irregular pigment, muscle weaken

Question 35

As they extend from the retina to the brain, nerve fibers?

Answer 35

From the nasal half of each retina cross to reach the opposite visual cortex

Question 36

Which cranial nerve carries visual impulses to the brain?

Answer 36

II

Question 37

What is refraction?

Answer 37

Involves bending of light rays by cornea and lens to focus an image on the retina

Question 38

What is pupil constriction?

Answer 38

Constriction of smooth muscles in the iris changes the pupil diameter to control light entering the eye and prevent light scattering around the retina

Question 39

Describe the pupil?

Answer 39

Opening in the eye which allows light to travel into the eye

Question 40

Describe ways in which an image can be formed

Answer 40

Refraction - bending of light rays by the cornea and retina to focus an image on central fovea Accommodation - lens increases/decreases curvature to focus the image on the retina Convergence - medial movement of the eyeballs to keep both eyes focused on object Pupil constriction - prevents light rays entering the eye from the periphery of the lens