Eyeball Physiology

Question 1

What is a wavelength?

Answer 1

Peak to peak

Question 2

What is a focal point?

Answer 2

The point at which rays or waves converge after refraction

Question 2

What is far vision?

Answer 2

Normal vision

Question 2

What does refraction mean?

Answer 2

Bending light

Question 2

What is near vision?

Answer 2

Looking at something up close

The closest point we can see something up close clearly

Question 3

What are the 3 parts to near vision?

Answer 3

Accommodation, constriction of pupil (parasympathetic) and convergence of eyeball

Question 3

What are the inner segments?

Answer 3

Connecting cilium that connects to the cell body (in the neural layer)

Question 3

What is near vision accommodation?

Answer 3

Process that increases the refractory power of the lens

Question 3

What is convergence of the eyeballs?

Answer 3

Crossing your eyes

Question 3

What controls the ciliary bodies?

Answer 3

Parasympathetic fibers and oculomotor nerves

Question 3

What is constriction of the pupils?

Answer 3

The sphincter pupillae muscles of the iris enhance the effect of accommodation

Question 3

What are the accommodation steps?

Answer 3

The ciliary muscles contract, pulling the ciliary body toward the pupil and inward, releasing tension in the ciliary zonule

Question 3

What is nearsightedness

Answer 3

Can’t see far away

Question 3

What is myopia?

Answer 3

Nearsightedness and eye is too long

Question 3

What are the outer segments?

Answer 3

The receptive regions of rods and cones

Question 4

What are the 2 vision defects?

Answer 4

Myopia and hyperopia

Question 4

What is farsightedness?

Answer 4

Can’t see close up

Question 4

What is hyperopia?

Answer 4

Farsightedness and eye is too small

Question 4

What is a visual pigment (photopigment)?

Answer 4

They trap light and change shape

Question 5

What happens to the lens when ciliary muscles relax?

Answer 5

Gets flattened

Question 6

What happens to the lens when ciliary muscles constrict?

Answer 6

Gets rounded (fat)

Question 7

The fatter the lens, the more….

Answer 7

strentgh

Question 8

What is retinal?

Answer 8

A light-absorbing molecule

Question 9

What are the parts of a visual pigment?

Answer 9

Retinal and opsin

Question 9

What is an opsin?

Answer 9

A protein

Question 10

Rods vs cones: noncolor visions

Answer 10

Rods

Question 11

Rods vs cones: Color vision

Answer 11

Cones

Question 12

Rods vs cones: High sensitivity

Answer 12

Rods

Question 13

Rods vs cones: Low sensitivity

Answer 13

Cones

Question 14

Rods vs cones: Mostly in central retina

Answer 14

Cones

Question 14

Rods vs cones: Mostly in peripheral retina

Answer 14

Rods

Question 15

Retinal and opsin combine together and form...

Answer 15

4 types of visual pigments

Question 16

Retinal is related to vitamin...

Answer 16

A

Question 16

Step 1 activation bleaching of pigment:

Answer 16

Retinal (cis-retinal) combined with opsin = forms rhodopsin

Question 17

Step 2 activation bleaching of pigment:

Answer 17

Light absorption by rhodopsin triggers a rapid series of steps in which retinal changes from cis to trans and releases opsin

Question 18

Step 3 activation bleaching of pigment:

Answer 18

Retinal changes from trans back to cis

Question 19

Step 1 in the dark: cGMP-gated channels....

Answer 19

open. Photoreceptor depolarizes

Question 20

Step 2 in the dark: Voltage gated calcium channels _____ in synaptic terminals

Answer 20

open

Question 21

Step 6 in the dark: Does an action potential occur?

Answer 21

No

Question 22

Step 3 in the dark: Neurotransmitter is...

Answer 22

released

Question 23

Step 5 in the dark: Hyperpolarization _______ voltage-gated calcium channels, ______ neurotransmitter release

Answer 23

closes, inhibiting

Question 24

Step 4 in the dark: Neurotransmitter causes __________ in bipolar cell

Answer 24

hyperpolarization

Question 25

Step 1in the light: cGMP-gated channels....

Answer 25

close, photoreceptor hyperpolarizes

Question 26

Step 2 in the light: Voltage gated calcium channels _____ in synaptic terminals

Answer 26

close

Question 27

Step 3 in the light: Neurotransmitter is...

Answer 27

released

Question 28

Step 4 in the light: Bipolar cells...

Answer 28

depolarizes

Question 29

Step 6 in the light: Does an action potential occur?

Answer 29

Yes

Question 30

Step 5 in the light: Depolarization _______ voltage-gated calcium channels, neurotransmitter is _______

Answer 30

opens, released

Question 31

What is light adapatation?

Answer 31

Moving from darkness to bright light - the sensitivity of the retina is still "set" for dim light

Question 32

What is dark adaptation?

Answer 32

Opposite of light adaptation: Cones stop functioning in low-intensity light The bright light bleached our rod pigments and the rods are still turned off

Question 33

Order of visual pathways:

Answer 33

Optic nerve, crosses in optic chiasma, optic tract, thalamus, primary visual cortex (occipital), association areas, midbrain (eye control) and hypothalamus (circadian rhythm: sleep-wake cycle)