Eye

Question 1

eyelid

function

Answer 1

protect eyeball, maintain moisture

Question 2

eyelid structure

Answer 2

thin skine externally
+ palpebral conjunctiva internal
+ tarsal plates “skeleton”

Question 3

eyelid glands

Answer 3

1. sebaceous of eyelashes (Zeis), bacterial infections = styes
2. apocrine of eyelashes (Moll), modified sweat glands
3. tarsal (Meibomian), sebaceous glands w/i tarsal plates>secretions slow evap of tears> open onto edge of eyelid
   -Chalazion = inflammation of tarsal glands

Question 4

conjunctiva

function

Answer 4

maintain moisture, lubricate outside of eye so no pain when blinking

Question 5

conjunctiva structure

Answer 5

two parts:
1. bulbar (cover sclera)
2. palpebral (cover inside eyelid)

stratified columnar w/ goblet cells to lubricate/protect anterior eye»_space; stratified squamous @corneoscleral limbus

Question 6

lacrimal apparatus function

Answer 6

maintain moisture, remove foreign materials via tears

Question 7

lacrimal gland

Answer 7

compound tubuloacinar shape

secretes lacrimal fluid aka tears
-sterile (mostly water) + lysozyme

Question 8

lacrimal fluid flow

Answer 8

lateral > medial
1. lacrimal gland
2. lacrimal duct
3. lacrimal canaliculi (strat squamous)
4. lacrimal sac (pseudostrat ciliated)
5. nasal cavity (pseudostrat ciliated)

pseduostratified ciliated columnar = respiratory epithelium

Question 9

chambers/segments of eye

Answer 9

1. anterior segment @ant to lens w/ aqueous humor
   - anterior chamber (cornea>iris)
   - posterior chamber (iris>lens)
2. posterior segment @post to lens w/ vitreous humor

Question 10

parts of anterior segment

Answer 10

1. ciliary body
2. iris
3. pupil
4. cornea
5. sclera

Question 11

parts of posterior segment

Answer 11

1. choroid
2. retina
3. vitreous body (transparent gel 99% water)
4. sclera

other 1% = collagen, hyaluronic acid, hyaloctyes, macrophages

Question 12

eye development

neuroectoderm

Answer 12

1. optic vesicle
2. optic cup
3. inner and outer layer
   -inner = neural retina
   -outer = retinal pigment epithelium (RPE)

Question 13

eye development

surface ectoderm

Answer 13

1. surface ectoderm
2. lens placode and corneal epithelium
   -lens placode >lens vesicle> lens

Question 14

lens structure

Answer 14

1. lens capsule- basal lamina of subcap
2. subcapsular epithelium- simple cuboidal, only on anterior lens
3. lens fibers- mature fibers w/o nuclei + acquire crystallins to inc refractory index

Question 15

layers of eye

general - 3

Answer 15

1. fibrous (sclera + cornea)
2. vascular (iris + ciliary body + choroid)
3. retina (RPE + neural retina)

Question 16

sclera

Answer 16

@fibrous layer, posterior 5/6 eye

mostly collagen + elastic fibers

all extraocular muscles insert

will continue to cornea @corneoscleral limbus

Question 17

cornea

Answer 17

anterior 1/6th eyeball

transparent and avascular
highly innervated
provides most refraction of light

Question 18

corneoscleral limbus structure

Answer 18

trabecular meshwork (drain aq humor from ant chamber) aka spaces of fontana >combine to form scleral venous sinus aka canal of schlemm

Question 19

flow of aqueous humor

Answer 19

1. produced by ciliary epithelium
2. secreted to post chamber
3. flow into ant chamber thru pupil
4. drain thru trabecular meshwork
5. drain in scleral venous sinus
6. drain to scleral veins

Question 20

cornea layers

Answer 20

1. epithelium
2. bowman’s membrane
3. stroma
4. pre-descemet
5. descemet membrane
6. endothelium

Question 21

epithelium of cornea

Answer 21

strat squamous non keratin, has surface cells w/ microvilli, richly inn, replaced every 7 days

layer 1/6

Question 22

bowman’s membrane

cornea

Answer 22

acellular/no regen, ends @ corneoscleral limbus, strengthens cornea + barrier to infectin

layer 2/6

Question 23

stroma

cornea

Answer 23

aka substantia propria, 90% of corneal thickness, orthogonal lamellae of collagen fibrils = transparency maintain

layer 3/6

Question 24

pre-descemet layer

cornea

Answer 24

protect cornea from damage, rupture = aq fluid leaking into cornea

layer 4/6

Question 25

descemet membrane

Answer 25

basal lamina of corneal endothelium, helps maintain curvature -secreted/maintained by corneal endothelial cells will thicken with age layer 5/6

Question 26

endothelium | cornea

Answer 26

simple squamous resp for metabolic exchanges of cornea + removes xs fluid from stroma layer 6/6

Question 27

iris | vascular layer

Answer 27

contractile diaphragm w/ central aperture (pupil) ant to lens via sphincter and dilator pupilae reg amount of light passing into eye

Question 28

pupillae muscles | iris

Answer 28

1. sphincter = constricts pupil via parasymp inn, in bright light 2. dilator = dilates pupil via symp inn, in dim light

Question 29

layers of iris

Answer 29

1. stroma= vascular, loose CT, melanocytes (eye color) + sphincter pupillae 2. pigment epithelium/PE = 2 rows of cuboidal cells (ant row is myoepithelium/basal row of dilater pupillae)

Question 30

ciliary body

Answer 30

ciliary muscle + ciliary processes muscle = sphincter muscle w/ parasymp inn, does accomodation processes= zonular fibers/suspensory ligs, lined w/ ciliary epithelium that secretes zonular fibers + aq humor

Question 31

accomodation

Answer 31

contract ciliary muscle = relax suspensory lig > lens to round for near vision relax ciliary muscle = tension on suspensory lig > flatten lens for far vision

Question 32

ciliary epithelium | of ciliary body

Answer 32

double layer of cuboidal cells but only outer is pigmented continuous w/ pigment epithelium of iris and nonphotosensitive retina

Question 33

choroid

Answer 33

@ b/t retina and sclera heavily pigments and vascularized layers: 1. choriocapillary = vascular layer for blood to outer layers of retina 2. bruch's membrane = fimly attach to RPE of retina

Question 34

retina layers

Answer 34

1. outer = RPE 2. inner = neural/retina proper w/ photosensitive cells + neurons

Question 35

retina regions

Answer 35

1. anterior = nonphotosensitive 2. posterior = photosensitive divided by ora serrata (marks ant extent of visual retina and choroid)

Question 36

fovea centralis | retina

Answer 36

area of highest visual activity bc highest density of cones NO RODS -conducting and association neurons deflected =maximal light penetration surrounded by macula lutea (yellow color, ganglion cell layer thickest)

Question 37

optic disc

Answer 37

where optic nerve pierces retina no photorecptors so blind spot central artery/vein enter then travels w/ nerve fiber layer for inner layers of retina

Question 38

age related macular degeneration

Answer 38

loss of photoreception in macula lutea = loss of central vision, peripheral vision unaffected dry AMD = most common, drusen disrupts retina OR wet AMD = neovascularization

Question 39

light pathway | general

Answer 39

light thru all 10 layers (photosens in outer + optic nerve fibers in inner) to reach rods/cones nerve impulse passed back thru layers to optic nerve fibers in inner lyaer

Question 40

neural retina cell types

Answer 40

1. association neurons = horizontal + amacrine 2. conducting = bipolar + ganglion 3. supporting = muller's cells 4. photosensitive cells = rods and cones

Question 41

association neurons

Answer 41

reg neural impulses aka quality control via filtering, facilitate impulses b/t cell layers horizontal and amacrine

Question 42

conducting neurons

Answer 42

transmission of visual impulses toward brain bipolar and ganglion (multipolar)

Question 43

supporting cells

Answer 43

provide structural and physiological support muller cells- cytoplasm spans thickenss of entire neural retina layers

Question 44

photosensitive cells

Answer 44

react w/ light rods and cones

Question 45

10 layers of retina

Answer 45

1. RPE 2. rods and cones 3. outer limiting membrane 4. outer nuclear layer 5. outer plexiform layr 6. inner nuclear layer 7. inner plexiform layer 8. ganglion cell layer 9. optic nerve fibers 10. inner limiting membrane

Question 46

RPE

Answer 46

-single layer cuboidal cells w/ microvilli that surround rods/cones + have melanin granules -melanin absorbs light, prevents reflection -maintain blood-retina barrier -phagocytosis and disposal of shed discs -store/supply vitamin A | retinal detachment b/t microvilli and R/C bc not solid

Question 47

rod and cone structure

Answer 47

1. inner segment = metabolic machinery 2. outer segment = site of photosensitivty, numerous rods + some cones

Question 48

retinal detachment

Answer 48

b/t RPE and layer of rods/cones RPE strongly attach to bruch membrane and choroid but not to neural retina bc of development layers from trauma or disease, treat w/ surgery if not then blindness

Question 49

rods

Answer 49

most numerous and sens to light -rhodopsin pigment reacts w/ light and dep on vitamin A black and white vision discs are sep from plasma membrane

Question 50

cones

Answer 50

less numerous than rods except in fovea, discs connect to plasma membrane 3 types: 1. red (long wavelengths) 2. green (medium) 3. blue (short) photopsin pigment reacts w/ light

Question 51

color blindness

Answer 51

red-green confusion from 1. deuteranopia (loss M/green cones) OR 2. protanopia (loss L/red cones) -both sex linked X chromo blue-yellow confusion from tritanopia (loss S/blue cones) autosomal chromo 7

Question 52

limiting membranes | retina layers

Answer 52

layer #3 = outer, not true membrane, apical boundary of muller cells layer #10 = inner, basal lamina of muller cells, sep retina from vitreous body

Question 53

nuclear layers | retina layers

Answer 53

#4 = outer, nuclei of photosensitive cells aka rods/cones #6 = inner, everything else (horizontal, amacrine, bipolar, muller) #8 = ganglion cells, nuclei of ganglion cells (form optic nerve), absent in fovea centralis

Question 54

plexiform layers

Answer 54

#5 = outer, proceses of photosensitive + bipolar + horizontal cells #7 = inner, processes of bipolar + ganglion + amacrine cells #9 = optic nerve fibers, central processes of ganglion cells converge

Question 55

visual processing

Answer 55

1. rods/cones react to light 2. pass info to bipolar cells 3. horizontal cells inhibit bad data 4. bipolar pass info to ganglion cells 5. amacrine cells inhibit bad data 6. central processes of ganglion form optic nerve to transmit visual info to brain - muller cells provide structure/metabolic support for other retinal cells, form inner and outer limiting membranes