12.2 Photo Reception

Question 1

What are the 3 layers of the eye?

Answer 1

External
Intermediate
Internal

Question 2

What is the the for the external layer of the eye?

Answer 2

Sclera

Question 3

What is the Sclera?

Answer 3

The white, tough, fibrous, external layer of the eye

Question 4

Where does light enter the eye?

Answer 4

Through the cornea

Question 5

What is the Cornea?

Answer 5

The transparent part of the Sclera at the front of the eye

Question 6

What is the intermediate layer of the eye called?

Answer 6

The Choroid

Question 7

What does the Choroid do?

Answer 7

Absorbs stray light rays that are not detected by photoreceptors. also contains blood vessels to nourish the eye

Question 8

What does the Choroid form toward the front of the eye?

Answer 8

the Iris

Question 9

What does the Choroid do behind the Iris?

Answer 9

The Choroid thickends and forms the ciliary muscles

Question 10

What does the ciliary muscle do?

Answer 10

Attaches to the lens which focuses images on the retina

Question 11

What is the internal layer of the eye called?

Answer 11

The Retina

Question 12

What is the Retina?

Answer 12

A thin layer of tissue that contains photoreceptors- Rods and cones

Question 13

What are Rods sensitive to?

Answer 13

Light intensity

Question 14

What are Cones sensitive to?

Answer 14

Different colors

Question 15

Where are the Cones found?

Answer 15

Packed more densely at the back of the eye called Fovea Centralis

Question 16

How do Rods and Cones send sensory impulses?

Answer 16

Through the Optic Nerve

Question 17

What does the lens do to the eye?

Answer 17

Divides the eye into 2 chambers

Question 18

What is the Anterior chamber?

Answer 18

The front of the lens

Question 19

What is the Posterior Chamber?

Answer 19

The back of the lens

Question 20

What is found in the Anterior Chamber?

Answer 20

A clear watery fluid called the Aqueous Humour

Question 21

What does the Aqueous Humor do in Anterior Chamber?

Answer 21

Maintains cell shape of the cornea and provides oxygen and nutrients to the surrounding cells including the lens and cornea

Question 22

What happens if the ducts that empty out the Aqueous humor are clogged?

Answer 22

Pressure can build up in the eye causing the delicate blood vessels to rupture leading to glaucoma, which leads to blindness

Question 23

What is the Posterior Chamber surrounded by?

Answer 23

The Retina

Question 24

What does the Posterior Chamber contain?

Answer 24

Clear jelly like fluid called Vitreous Humor

Question 25

What does the Vitreous Humor do?

Answer 25

Helps to maintain the shape of the eyeball and supports the surrounding cells

Question 26

What does the external layer contain?

Answer 26

The Cornea

Question 27

What does the Intermediate layer contain?

Answer 27

Sides and back of Choroid Iris Pupil Ciliary Muscles

Question 28

What does the Internal layer contain?

Answer 28

Rods Cones Fovea Centralis

Question 29

What does the Sclera do?

Answer 29

Protects and supports the eyeball

Question 30

What does the Cornea do?

Answer 30

Bends light rays into the eye

Question 31

What does the Choroid do?

Answer 31

Absorbs scattered light and contain blood vessels

Question 32

What does the Iris do?

Answer 32

Regulates the amount of light that enters the eye

Question 33

What is the Pupil?

Answer 33

The opening for light to enter the eye

Question 34

What do the Ciliary muscles do?

Answer 34

Changes the shape of the lens in order to focus

Question 35

What are Rods?

Answer 35

Photoreceptors that are sensitive to light

Question 36

What are Cones?

Answer 36

Photoreceptors that are sensitive to color

Question 37

What does the lens do?

Answer 37

Focusses light rays onto the Fovea Centralis

Question 38

What do the Humours do?

Answer 38

Support the eyeball with the pressure of fluids they contain

Question 39

What does the optic nerve do?

Answer 39

Transmits sensory information to the brain

Question 40

How is the image that is protected on the Fovea Centralis different than the actual object?

Answer 40

The image is smaller, upside down, and reversed from left to right

Question 41

How do the Ciliary muscles act when the object is far away?

Answer 41

The ciliary muscles relax and suspensory ligaments become taut causing the lens to flatten

Question 42

How do the Ciliary muscles act when an object is nearby?

Answer 42

The Ciliary muscles contract and the suspensory ligaments relax causing the lens to become rounded

Question 43

What is accomodation in the eye?

Answer 43

The ability of a lens to change shape in order to focus images clearly on the retina

Question 44

What is Cataracts?

Answer 44

When the protein structure in the lens starts to degenerate making it opaque and unable to have light pass through

Question 45

What is Astigmatism?

Answer 45

An uneven curvature on part of the cornea so it can not bend light rays so they meet the correct focal point

Question 46

What is Myopia?

Answer 46

Nearsightedness

Question 47

What is different in people with Myopia?

Answer 47

They eyeball is elongated so focussed light falls in front of the retina

Question 48

How is Myopia fixed?

Answer 48

Concave lenses

Question 49

What is Hyperopia?

Answer 49

Farsightedness

Question 50

What happens in Hyperopia?

Answer 50

The eyeball is short so light rays do not meet before they reach the retina

Question 51

What can fix Hyperopia?

Answer 51

Convex lenses

Question 52

Which photoreceptor responsible for Peripheral vision?

Answer 52

Rods

Question 53

Why does Peripheral vision lack color?

Answer 53

Due to the location of the Fovea Centralis and where the cones are

Question 54

What allows us to read?

Answer 54

Cones

Question 55

What is different about the 3 types of cones?

Answer 55

They each absorb a different wavelength of light

Question 56

What is color blindness caused by?

Answer 56

Lack or deficiency of a type of cones

Question 57

What do Rods contain?

Answer 57

A light absorbing pigment called rhodopsin which is composed of retinal and the protein opsin

Question 58

What do Rods release in the dark?

Answer 58

An inhibitory transmitter that inhibits nearby nerve cells

Question 59

What happens when Rods absorb light?

Answer 59

Rhodopsin splits into retinal Opsin. which stops the release of the inhibitory neurotransmitter allowing a transmission of the nerve impulse to the optic nerve

Question 60

What happens when light stimulates the rods and cones?

Answer 60

They stop releasing an inhibitory neurotransmitter into the synapse

Question 61

What happens when rods and cones stop releasing an inhibitory neurotransmitter into the synapse?

Answer 61

Bipolar cells then transfer a neural impulse to the ganglion cells. The axons of the ganglion cells form the optic nerve. An transmit the image to the occipital lobe of the brain

Question 62

Why is there a blind spot?

Answer 62

Because this is where the ganglion cells merge to form the optic nerve

Question 63

Why don't we normally see the blind spot?

Answer 63

Because each eye compensates for the visual information that the other misses

Question 64

Where is visual information processed?

Answer 64

The Cerebrum

Question 65

What happens in diabetic retinoplasty?

Answer 65

Capillaries in the retina burst spilling blood into the vitreous fluid and the retina

Question 66

What is retinal detachment?

Answer 66

When the retina becomes detached from the Choroid vessels that supply it with nutrients and oxygen

Question 67

What is macular degeneration?

Answer 67

When the cones are destroyed due to thickened choroid vessels. Resulting in a blind spot of central vision