Vision: Physiology

Question 1

If light rays are absorbed, not reflected, by an object, what do we see?

Answer 1

Dark object

Question 2

If light rays of many wavelengths are reflected off an object, what do we see?

Answer 2

White object

Question 3

If red light rays are absorbed, but blue one are reflected, what do we see?

Answer 3

Blue object

Question 4

What is LIGHT?

Answer 4

Packets of energy travelling in wavelike fashion at high speed (300,000 km/s)

Question 5

How fast does LIGHT travel through less dense materials?

Answer 5

Very fast

Question 6

How fast does LIGHT travel through dense material?

Answer 6

Slowly

Question 7

How fast does LIGHT travel through more dense materials?

Answer 7

Slower

Question 8

What does “refraction” mean?

Answer 8

LIGHT is bending

Question 9

How does the density of an object affect refraction?

Answer 9

The more dense, the more it refracts

Question 10

How will LIGHT RAYS from a distant object arrive at your eye?

Answer 10

They will arrive in parallel lines (see notes for a pic)

Question 11

How will LIGHT RAYS from a close object arrive at your eye?

Answer 11

They will diverge (see notes for a pic)

Question 12

Where does 75% of REFRACTION occur?

Answer 12

In the CORNEA

Question 13

Why does most REFRACTION occur at the CORNEA?

Answer 13

Because the biggest difference in density occurs between air (1.00) and the CORNEA (1.38), and more density = more REFRACTION

Question 14

Where does 25% of REFRACTION occur?

Answer 14

At the LENS

Question 15

Why is there less REFRACTION at the LENS than there is at the CORNEA?

Answer 15

Because the difference in density between the AQUEOUS HUMOR (1.33) and the LENS(1.40) is much smaller than the difference of density between air and the CORNEA

Question 16

Can the REFRACTIVE power of the CORNEA ever change?

Answer 16

No, because the shape of the CORNEA is unchanging

Question 17

Can the REFRACTIVE power of the LENS ever change?

Answer 17

Yes, because the LENS can change shape

Question 18

When is the REFRACTIVE power of the LENS decreased?

Answer 18

When the LENS is flat

Question 19

When is the REFRACTIVE power of the LENS increased?

Answer 19

When the LENS is round

Question 20

Are our eyes preset for close-up vision?

Answer 20

No, they are preset for distant vision

Question 21

What is happening to structures inside the eye when focusing on a distant object?

Answer 21

CORNEA = unchanging (refracts LIGHT)
LENS = flat (refracts LIGHT)
NEURONS = sympathetic
CILIARY MUSCLES = relaxed, dilated
CILIARY ZONULE = pulled taut

Question 22

What is BINOCULAR VISION?

Answer 22

Parallel RAYS can land on FOVEA when eyes face forwards

Question 23

Why do PUPILS dilate when focusing on a distant object?

Answer 23

To allow more parallel LIGHT RAYS in

Question 24

What stimulates the PUPILLARY DILATOR MUSCLES to allow more LIGHT in?

Answer 24

The sympathetic system

Question 25

In distant vision, when the PUPILLARY DILATOR MUSCLES contract, the
_________ ___________ _______ are
____________ ____.

Answer 25

PUPILLARY CONSTRICTOR MUSCLES

relaxed/pulled open