8.4 Vision

Question 1

What produces the aqueous humor?

Answer 1

cilliary processes

Question 2

Functions of aqueous humor?

Answer 2

• provides nutrients for the lens and cornea
• creates refractive power of the eye

Question 3

Vascular part of the eye includes

Answer 3

Choroid

ciliary body

iris

Question 4

What gives the majority of refractive power of the eye

Question 5

What controlls the ciliary muscles?

Answer 5

Parasympathetic NS

Question 6

Describe the müller cells

Answer 6

Long glial cells

maintain extracellular environment by regulating K⁺ levels

NT uptake

glycogen storage

Question 7

Who is more sensitive to light and why

Answer 7

Rods

bcs. In cones only a few synaps on a bipolar cell

Question 8

Difference in activation of rods and cones?

Answer 8

rods have more Rhodopsin so less photons are needed for the activation of it (only one photn is needed)

Question 9

What does Rhodopsin contain

Answer 9

Opsin and Retinal

Question 10

Draw a diagram of photoreception

Answer 10

Question 11

Define what is near point

Answer 11

the point nearest the eye at which an object is accurately focused on the retina when the maximum degree of accommodation is employed

Question 12

How does the eyeball look like im hyperopia?

Answer 12

short eyeball

corrected by convex lens

Question 13

How does the eyeball look like im myopia?

Answer 13

Long eye

fixed with concave lenses

Question 14

What is the pressure inside the eyeball?

Answer 14

22 mmHg (Bernandlevi)

Question 15

Describe the flow of the aqueous humor

Answer 15

Question 16

What is the major refractive element of the eye?

Answer 16

Cornea (43 diopter)

Question 17

What holds the lens in place?

Question 18

Describe the layers of the retina

Answer 18

Question 19

The eye can dist. 2 aspects of light

______

______

Question 20

What are cones responsible for?

Answer 20

Best in day light, color vision

Question 21

Main visual pathway in thalamus is ______

Answer 21

LGB

Question 22

Lens equation

Answer 22

Question 23

Focal power of resting and accommodation (what cahnges?)

Answer 23

Question 24

What is astigmatisms?

Answer 24

Unequal focal power on different directions

Question 25

What is the intraocular pressure?

Answer 25

15mmHg

Question 26

What happens in glaucoma?

Answer 26

Intraocular pressur increases -\> optic nerve damage -\> vision loss

Question 27

Distribution of rods and cons in the retina

Answer 27

Question 28

Three types pf vision

Answer 28

Scotopic (only rods) mesopic (both) photopic (only cones)

Question 29

What is Rhodopsin?

Answer 29

Visual pigment GPCR for light Rhodopsib = opsin (7TM protein) + 11-cis retinal

Question 30

What happens in vit A deff?

Answer 30

Night blindness

Question 31

Phototransduction of rods in light

Answer 31

Light ► Rhodopsin (changes to metarhodopsin II) ► Gt activation (transducin) ► a_t acrivstes cGMP Phosphodiesterase (PDE) ► cGMP decreases ► CNG (Cyclic Nucleotide Gated) channels close (Na, Ca influx decreases) ► hyperpolarization ► Glu release decreases

Question 32

Describe the dark current of photoreceptors

Answer 32

CGMP is always produced and not broken down so CNG channels are open and influx of Na and Ca happens ► depol ► Glu release

Question 33

What does light evokes in photoreceptors?

Question 34

Define Critical Flicker Fusion Frequency

Answer 34

the frequency at which a flickering light is perceived as continuous

Question 35

When does Rhodopsin form?

Question 36

Two things can happen when hypopolarization of the photoreceptor membrane

Answer 36

Question 37

There are two types of receptors on _____ and \_\_\_\_\_cells 1. \_\_\_\_\_ 2. \_\_\_\_\_

Answer 37

There are two types of receptors on bipolar and horizontal cells 1. Ionotropic 2. Metabotropic

Question 38

ionotropic receptors, which are depolarizing (excitatory), and metabo- tropic receptors, which are hyperpolarizing (inhibitory)

Answer 38

ionotropic receptors, which are depolarizing (excitatory), and metabo- tropic receptors, which are hyperpolarizing (inhibitory)

Question 39

Draw the optic pathway

Answer 39

Question 40

Why are horizontal cells important?

Question 41

Explain of herman grid illusion

Answer 41

Question 42

3 types of cones:

Answer 42

1) blue S (short) 2) green M (medium) 3) red L (large) by wavelength

Question 43

3 layers of the eye

Answer 43

1. outer fibrous (sclera, cornea) 2.