Lecture 15: Vision

Question 1

What neurotransmitter does photoreceptors secrete?

Answer 1

Glutamate

Question 2

The amount of light reaching the retina is controlled by the what

Answer 2

IRIS

Question 3

The Ciliary muscle helps to what

Answer 3

Control the shape of the Lens

Question 4

What are the 4 layers of protection of the eye

Answer 4

Eyeball
Eyelid
Eyelashes
Tears

Question 5

Describe the Iris

Answer 5

Controls amount of light that can enter by using 2 set of smooth muscles

Circular = constricts
Radical = Dilates

Question 6

Describe the Pupil

Answer 6

opening where light enters

Question 7

Describe the Lens

Answer 7

Focus light on the retina (Fovea

Question 8

Describe the Sclera

Answer 8

Fluid filled spherical structure
Visible white layer of the eye
tough layer of connective tissue

Question 9

Describe the Cornea

Answer 9

Fluid filled spherical structure
Anterior
Transparent layer that lets light rays through

Question 10

Describe the Choroid

Answer 10

Fluid filled spherical structure
Contains blood vessels nourishing retina
Contains melanin under retina
Underneath Sclera

Question 11

Describe the retina

Answer 11

Fluid filled spherical structure
Filled with Rods and cones
Axons of visual nerve fibers
Outer pigment cells

Question 12

Describe the Posterior cavity

Answer 12

Fluid filled
Between lens and retina
Gelantinous viterious humor

Question 13

Describe the anterior cavity

Answer 13

Fluid Filled
Between cornea and lens
Aqueous humor

Question 14

What two things dilate or constrict the pupils

Answer 14

Circular/ radical muscles

Actions of the PNS/SNS

Question 15

The Lens bends ____

Answer 15

Light rays

Question 16

Accommodation in talking about vision relates to what

Answer 16

focusing

Question 17

When were looking at something from a distant describe the eye

Answer 17

Lens flat, weak
Ciliary muscles relaxed
Ligaments tight

Question 18

when were looking at something near, describe the eye

Answer 18

Lens rounded, strong
Ciliary muscles contracted (PNS stimulated)
Slack Ligaments

Question 19

What is the main neurotransmitter involved in accommodation and why

Answer 19

ACh

causes contraction of ciliary muscles and constriction of rings

Question 20

Describe Myopia and how its cured

Answer 20

Near-sightedness

Focal point falls before the retina

Corrected with concave lens )0

Question 21

Describe Hyperopia and how its cured

Answer 21

Far-sightedness

Focal point falls behind retina

Corrected with Convex lens (0

Question 22

Describe Presbyopia and how its cured

Answer 22

Aging

Ability to shape lens is lost

Corrected with bifocal (reading glasses)

Question 23

Describe Rods

Answer 23

More
Grayscale 
High sensitive
low acuity
Lots Converge on ganglion cells
Located in peripheral retina

Question 24

Describe cones

Answer 24

less
Colour vision
Lower sensitive
High acuity
Located in Fovea

Question 25

What do Ganglion cells do

Answer 25

process visual information that begins when light enters eye

Question 26

What do horizontal cells do

Answer 26

Help integrate and regulate input from photoreceptors and provide IPSP feedback to rods and cones

Question 27

what do Bipolar cells do

Answer 27

Located between photoreceptors and ganglion cells

Directly or indirectly transmit signals from photoreceptors to ganglion cells

Question 28

Describe Zonules

Answer 28

Fibrous strands connection ciliary body and lens

Question 29

Describe the Orbit

Answer 29

Eye socket

Question 30

Where is rhodopsin located

Answer 30

disk of rods and cones

Question 31

How is rhodopsin made

Answer 31

Opsin + Retinal

Question 32

What happens when it is dark

Answer 32

Rhodopsin inactive cGMP high

Cells depolarized constantly by Na+ and Ca+

Question 33

What happens when its light

Answer 33

Rhodopsin bleached by light activates it
Decrease in cGMP = CNG channels to close, hyperpolarizing the cell
Less transmitter released onto bipolar cells