Visual Part 1

Question 1

What part of the brain processes “What” an object is?

Answer 1

The ventral/ Temporal lobe

Question 2

What part of the brain processes “Where” an object is?

Answer 2

The dorsal/Parietal lobe

Question 3

How does the CNS maintain a tolerable level os sensory stimulation?

Answer 3

Feedback control

Question 4

What are the three layers of the eyeball and what dural layers are they analogous to?

Answer 4

fibrous coat (dura); vascular coat (arachnoid and pia); nervous coat (CNS)

Question 5

What makes up the fibrous coat?

Answer 5

the sclera and the cornea

Question 6

What part of the fibrous coat is avascular?

Answer 6

the cornea

Question 7

What is the sclera made of?

Answer 7

dense white CT

Question 8

What is the uvea/ uveal tract?

Answer 8

the vascular coat

Question 9

What is in the vascular coat?

Answer 9

the choroid plexus, the ciliary body and the iris

Question 10

What two structures refract light?

Answer 10

The cornea and the lens

Question 11

What structure controls a majority of the light refraction?

Answer 11

The cornea

Question 12

What are the five layers of the cornea?

Answer 12

Epithelium; Bowmans basement membrane; Stroma; Descemets basement membrane; Endothelium

Question 13

What type of histology is seen in the cornea?

Answer 13

The epithelial layer is stratified squamous; The endothelial layer is simple squamous, all non-keratinizing

Question 14

What is a function of Bowmans membrane?

Answer 14

reduces the spread of infections. It also cannot regenerate

Question 15

What two layers in the cornea control the passage of substances from the aqueous humor to the stroma?

Answer 15

The endothelial layer and Descemets basement membrane

Question 16

Where are corneal epithelial stem cells located?

Answer 16

At the junction of the sclera and the cornea, called corneoscleral limbus

Question 17

What are corneal stem cells called?

Answer 17

transient amplifying cells (TACs)

Question 18

How is DNA protected from UV light in the cornea?

Answer 18

By nuclear ferritin

Question 19

How does the lens receive nutrients?

Answer 19

diffusion from humor

Question 20

How is the lens held in place?

Answer 20

zonule fibers from the ciliary body called suspensory ligaments

Question 21

How is the resting convexity of the lens maintained?

Answer 21

outward pull of suspensory ligaments, inward pull by intrinsic elastic fibers

Question 22

What is the lens capsule made of?

Answer 22

collagen IV and glycoprotein

Question 23

How and where is the lens regenerated?

Answer 23

The germinal zone- new lens cells migrate to the mediel eye and lose nuclei

Question 24

What is presbyobia and what is it caused by?

Answer 24

far sightedness- caused by loss of elasticity with age, so loss of resting convexity

Question 25

What are cataracts caused by?

Answer 25

build-up of Fe or ROS causing damage to the lens and a los of opaqueness

Question 26

Decreased convexity of the lens causes near or far vision?

Answer 26

far vision

Question 27

Increased convexity of the lens causes near or far vision?

Answer 27

near vision

Question 28

What muscle controls lens convexity? What is this process called?

Answer 28

ciliary bodies that control suspensory ligament tension, is called accomodation

Question 29

When the ciliary muscle is relaxed, what is the shape of the lens? What type of objects are seen? (near/far?)

Answer 29

stretched out, thin; Distant objects are seen

Question 30

When the ciliary muscle is tensed, what is the shape of the lens? What type of objects are seen? (near/far?)

Answer 30

smaller diameter lens, but is bulged posteriorly; near objects are seen

Question 31

What is myopia? What is it caused by?

Answer 31

near-sightedness, caused by the eyeball being too long, so light focuses in front of the retina

Question 32

What is hyperopia? What is it caused by?

Answer 32

far sightedness, caused by the eyeball being too short, so light focuses behind the retina

Question 33

Do near or distant objects require greater refraction by the lens?

Answer 33

nearby objects (distant objects are close to parallel)

Question 34

Where is the aqueous humor produced? Where does it drain?

Answer 34

the ciliary body, drains via the canal of Schlemm/scleral venous sinus

Question 35

What are some causes of glaucoma?

Answer 35

blocked flow of aqueous humor through the canal of schlemm, adherence of the iris to the lens, too much production of aqueous humor.

Question 36

What is glaucoma? What can result from glaucoma?

Answer 36

increased pressure in the anterior chamber of aqueous humor. Can cause intraocular pressure that can damage the optic nerve

Question 37

What are three components of the IRIS?

Answer 37

striations of CT, blood vessels and smooth muscle

Question 38

What are two muscles within the iris?

Answer 38

constrictor and dilator pupilae

Question 39

Where is the melanin in the iris?

Answer 39

distributed throughout the stroma/CT layer, but highly concentrated in the pigmented posterior epithelial layer.

Question 40

What determines eye color?

Answer 40

The distribution of melanin throughout the CT or lack thereof (melanin concentrated in the pigmented epithelium causes blue eye color)

Question 41

What is Rayleigh scattering and how does it explain the blue sky?

Answer 41

shorter wavelengths of light are refracted more that longer wavelengths of light. blue light (shorter wavelength) gets refracted more, so we see it more often.

Question 42

Why is melanin brown?

Answer 42

it absorbs blue and green colors, reflecting red/yellow/brown colors

Question 43

What does the iris do?

Answer 43

Controls the aperture of the eye, thereby also controlling the range of focus

Question 44

What two muscles are in the iris? What type of innervation controls them?

Answer 44

Sphincter pupillae (parasympathetic) and dilator pupillae (sympathetic)

Question 45

A smaller pupil increases or decreases the range of focus?

Answer 45

Increase

Question 46

A larger pupil size will increase or decrease the range of focus?

Answer 46

Decrease

Question 47

What is the parasympathetic pathway of iris innervation?

Answer 47

Oculomotor nerve (CN3) --> parasympathetic ciliary ganglion on posterior eye, decreases pupil size

Question 48

What is the sympathetic pathway of iris innervation?

Answer 48

Spinal cord--> superior cervical ganglion . Postganglionic nerves project along arteries to the iris

Question 49

What three cranial nerves enter the superior orbital fissure?

Answer 49

CN III, IV and V

Question 50

What are some things that can become 'floaters'?

Answer 50

Hyaloid canal vestiges; age-related depolymerization of collagen, due to water loss the collagen can coagulate.

Question 51

What is the vitreous body made of?

Answer 51

99% water; hyaluronic acid and type II collagen fibers

Question 52

Where does the lens placode form?

Answer 52

Where the rostral neural tube contacts ectoderm.

Question 53

What does the rostral part of the neural tube form?

Answer 53

The cerebral hemispheres and the eyes

Question 54

Is the lens of the eye derived from neural tissue or ectoderm?

Answer 54

Ectoderm

Question 55

What does the neural layer of the optic vesicle become?

Answer 55

Neurons and photoreceptors

Question 56

What does the pigmented layer of the optic vesicle form?

Answer 56

The retinal pigment epithelium

Question 57

What tissue types are the sclera and choroid derived from?

Answer 57

Embryonic meningeal tissues (mesoderm)

Question 58

What surrounds the optic nerve?

Answer 58

Dura, arachnoid and pia mater