Lecture 7: Vision I

Question 1

Refraction

Answer 1

Bending of light waves at angulated surface of transparent material

Question 2

Refractive index

Answer 2

Ratio of the velocity of light in air to velocity of light travelling in a substance

Question 3

What is the RI of air?

Answer 3

1.00

Question 4

Refractive power

Answer 4

Measure of how much a lens bends light waves, measured in diopters

Question 5

Diopter

Answer 5

1 meter/focal length of a lens

Question 6

Focal point

Answer 6

Point through which all parallel rays of light will pass after passing through each part of the lens

Question 7

Focal length

Answer 7

Distance from the center of the lens to the focal point

Question 8

What is the function of the iris?

Answer 8

Controls the amount of light entering the eye

Question 9

What happens to the depth of focus in the lens as the pupillary diameter decreases?

Answer 9

Increases

Question 10

Emmetropia

Answer 10

Normal eye regarding depth of focus; distant objects seen clearly

Question 11

Hypertropia

Answer 11

Farsightedness; eyeball too short or lens is too weak; distant objects seen clearly

Question 12

What type of lenses would be used to correct hypertropia?

Answer 12

Convex lens

Question 13

Myopia

Answer 13

Nearsightedness; eyeball too long; light rays focused in front of retina when ciliary muscle completely relaxed

Question 14

What type of lenses would be used to correct myopia?

Answer 14

Concave spherical lens

Question 15

Visual acuity

Answer 15

Measure of the resolving power of the eye

Question 16

What is the maximum visual acuity for two-point sources of light?

Answer 16

1.5-2 micrometers

Question 17

Resolving power

Answer 17

Ability of objects to be perceived as two points of light

Question 18

What forms the aqueous humor of the eye?

Answer 18

Ciliary processes

Question 19

What is the path of flow for the aqueous humor?

Answer 19

Anterior chamber to Canal of Schlemm to the aqueous veins in the sclera

Question 20

What is a tonometer and how does it work?

Answer 20

Tonometer measures intraocular pressure by measuring the displacement of the cornea

Question 21

Glaucoma

Answer 21

Abnormally high intraocular pressure; can cause blindness and neuronal damage if severe

Question 22

What photosensitive pigment is observed in rods?

Answer 22

Rhodopsin

Question 23

What photosensitive pigments are observed in cones?

Answer 23

Three different “opsins” or color pigments

Question 24

What is the purpose of the rhodopsin-retinal visual cycle?

Answer 24

Regenerate rhodopsin

Question 25

What is rhodopsin composed of?

Answer 25

Scotopsin and 11-cis retinal

Question 26

What occurs regarding ion flow during a rod’s exposure to light?

Answer 26

Excited; increases negativity of intrarod membrane potential and decomposition of rhodopsin; hyperpolarization

Question 27

What occurs regarding ion flow in a rod during darkness?

Answer 27

Membrane is leaky to Na+ ions which flow in and neutralize negativity of cell

Question 28

What is the maximum refractive power of the human eye?

A. 1 diopter
B. 5 diopters
C. 20 dipoters
D. 60 diopters

Answer 28

D. 60 diopters

Question 29

What refers to the phenomenon of the eyeball being too short?

A. Emmetropia
B. Hyperopia
C. Myopia
D. Nearsightedness

Answer 29

B. Hyperopia

Question 30

What is the product of Rhodopsin + Light?

A. Scotopsin + 11-cis retinal
B. Scotopsin + 11-cis retinol
C. Scotpsin + all-trans retinal
D. Rhodopsin + all-trans retinal

Answer 30

C. scotopsin + all-trans retinal

Question 31

Under dark conditions, what is the electronegativity inside the membrane of the outer segment of the rod?

A. -40 mV
B. -70 mV
C. -80 mV
D. -20 mV

Answer 31

A -40 mV