Module 4

Question 1

What are the five special senses?

Answer 1

Sight, hearing, equilibrium, taste, and smell.

Question 2

What structures protect the eye?

Answer 2

Bony orbit, fat cushion, eyelids, eyelashes, and eyebrows.

Question 3

What is the function of the lacrimal apparatus?

Answer 3

Produces tears that lubricate the eye and contain antibodies and lysozyme.

Question 4

What are the three tunics of the eyeball?

Answer 4

Fibrous layer, vascular layer, and sensory layer.

Question 5

What two structures make up the fibrous layer of the eye?

Answer 5

Sclera and cornea.

Question 6

What is the main function of the cornea?

Answer 6

Allows light to enter the eye and bends the light for focusing.

Question 7

What are the components of the vascular layer (uvea)?

Answer 7

Choroid, ciliary body, and iris.

Question 8

What does the ciliary body do?

Answer 8

Controls lens shape and anchors the suspensory ligaments.

Question 9

What muscle constricts the pupil?

Answer 9

Sphincter pupillae (parasympathetic control).

Question 10

What muscle dilates the pupil?

Answer 10

Dilator pupillae (sympathetic control).

Question 11

What are the photoreceptors in the retina?

Answer 11

Rods and cones.

Question 12

What is the function of rods?

Answer 12

Detect dim light and provide peripheral vision.

Question 13

What is the function of cones?

Answer 13

Provide sharp, color vision in bright light.

Question 14

Where is the highest concentration of cones found?

Answer 14

Fovea centralis of the retina.

Question 15

What causes the ‘blind spot’ in the eye?

Answer 15

Optic disc lacks photoreceptors.

Question 16

What are the steps of the light pathway through the eye?

Answer 16

Cornea → aqueous humor → lens → vitreous humor → retina.

Question 17

What is the function of aqueous humor?

Answer 17

Supports, nourishes, and removes waste in the anterior segment.

Question 18

What is the function of vitreous humor?

Answer 18

Transmits light and supports the posterior part of the eye.

Question 19

How does the lens focus light for close vision?

Answer 19

Ciliary muscles contract, zonular fibers relax, and the lens bulges.

Question 20

How does the lens focus light for distant vision?

Answer 20

Ciliary muscles relax, zonular fibers tighten, and the lens flattens.

Question 21

What lens corrects myopia?

Answer 21

Concave lens.

Question 22

What lens corrects hyperopia?

Answer 22

Convex lens.

Question 23

What vitamin is important for photopigments?

Answer 23

Vitamin A.

Question 24

What pigment is found in rods?

Answer 24

Rhodopsin.

Question 25

What three pigments are found in cones?

Answer 25

Blue, green, and red opsins.

Question 26

What causes photoreceptors to hyperpolarize?

Answer 26

Light exposure leads to cGMP breakdown and channel closure.

Question 27

What happens to bipolar cells in light?

Answer 27

They depolarize due to reduced inhibition and stimulate ganglion cells.

Question 28

Where do optic nerves cross?

Answer 28

At the optic chiasm (only medial fibers cross).

Question 29

Where do visual signals go after the thalamus?

Answer 29

To the visual cortex in the occipital lobe via optic radiation.

Question 30

What are the three main parts of the ear?

Answer 30

Outer ear, middle ear, and inner ear.

Question 31

What happens to the ciliary muscles when focusing on distant objects?

Answer 31

They relax.

Question 32

What happens to the zonular fibres during distant vision?

Answer 32

They tighten.

Question 33

What shape does the lens take for distant vision?

Answer 33

The lens becomes flat.

Question 34

Which nervous system controls distant vision focusing?

Answer 34

The sympathetic nervous system.

Question 35

What kind of light rays enter the eye from distant objects?

Answer 35

Nearly parallel rays.

Question 36

What happens to the ciliary muscles during close vision?

Answer 36

They contract.

Question 37

What happens to the zonular fibres when viewing close objects?

Answer 37

They loosen.

Question 38

What shape does the lens become for close vision?

Answer 38

The lens bulges.

Question 39

Which nervous system controls close vision focusing?

Answer 39

The parasympathetic nervous system.

Question 40

What is accommodation of the lens?

Answer 40

Changing the lens shape by ciliary muscles to increase refractive power.

Question 41

Why do pupils constrict during close vision?

Answer 41

To prevent divergent light rays from entering the eye.

Question 42

What is the convergence of the eyeballs?

Answer 42

Medial rotation of the eyeballs toward the object being viewed.

Question 43

Which cranial nerve controls accommodation and pupil constriction?

Answer 43

The oculomotor nerve (CN III).

Question 44

What is the role of somatic motor fibres in close vision?

Answer 44

They control convergence of the eyeballs.

Question 45

Why is lens accommodation important for near vision?

Answer 45

It increases the lens's refractive power to focus close objects.