eye

Question 1

3 tunics of the eye

Answer 1

fibrous tunic
vascular tunic
nervous tunic

Question 2

contents of the fibrous tunic

Answer 2

sclera and cornea

Question 3

what is the cornea?

Answer 3

transparent sclera extension that overlies the iris

Question 4

what is the limbus?

Answer 4

junction of the sclera and cornea

Question 5

5 layers of the cornea

Answer 5

epithelium
bowman's layer- dense CT, acellular
stroma
Descemet's membrane- thick BM from corneal endothelium
endothelium

Question 6

describe corneal epithelium

Answer 6

3 cell types- basal, wing, superficial
basal- large, rest on Bowman's mem
wing- crescent, polyhedral 
superficial-squamous, outermost, high turnover
highly innervated, blink reflex

Question 7

describe the corneal stroma

Answer 7

thickest layer- collagen layers at 90* angles, keratocytes

Question 8

what are keratocytes?

Answer 8

“fibroblast-like” support cells of the corneal stroma

Question 9

describe the corneal endothelium

Answer 9

single cell layer
does not regenerate
resorbs fluid from the stroma to maintain transparency of the stroma

Question 10

3 contents of the vascular tunic

Answer 10

iris, ciliary body, choroid

Question 11

what determines eye color?

Answer 11

number of melaocytes in the iris
high # = brown
low # = blue

Question 12

where is the pigmented portion of the iris?

Answer 12

posterior aspect

Question 13

pupillary constructor mm

Answer 13

at the edge of the iris, parasympathetic control

Question 14

pupillary dilator mm

Answer 14

more diffuse location, sympathetic control

Question 15

2 layers of the ciliary body

Answer 15

Epithelial (inner)

Uveal (outer)

Question 16

describe the parts of the inner, epithelial layer, of the ciliary body

Answer 16

• pars plicata- folded processes that produce aqueous humor, appear pigmented
• pars plana- site of vitrectomy

Question 17

describe the parts of the outer, uveal layer

Answer 17

houses vessels and ciliary mm

zonule of zinn- suspensory ligament

Question 18

what is the role of the ciliary mm?

Answer 18

accommodation
contacts- lends bends
relaxes- lens flat

Question 19

describe the route of aqueous humor

Answer 19

ciliary body releases into posterior chamber
moves to ant chamber between iris and lens
moves through trabecular network
into canal of schlemm then to vitreal cavity

Question 20

what is the iridiocorneal angle?

Answer 20

corner of the anterior chamber through which fluid exits

Question 21

5 cell types of the retina

Answer 21

• photoreceptors (rods, cones)
• horizontal cells
• bipolar cells
• amacrine cells
• ganglion cells

Question 22

3 glial cells of the retina

Answer 22

Muller cells
astrocytes
microglia

Question 23

describe muller cells

Answer 23

in ILM and ELM

participate in gluconeogenesis, removal of wastes, release of NTs, potassium homeostasis and insulation

Question 24

describe astrocytes

Answer 24

associated with ganglion cell axons and bv

part of the blood-retinal barrier

Question 25

describe microglia

Answer 25

mesodermal origin

dormant until infection and then participate in phagocytosis

Question 26

10 layers of the retina from internal to external

Answer 26

• internal limiting membrane
• nerve fiber layer
• ganglion cell layer
• inner plexiform layer
• inner nuclear layer
• outer plexiform layer
• outer nuclear layer
• external limiting membrane
• photoreceptor layer
• retinal pigment epithelium

Question 27

what are the 2 segments of the photoreceptor layer?

Answer 27

inner- contains organelles

outer- direct contact with retinal pigment epithelium microvilli

Question 28

what separates the retina from the choroid?

Answer 28

Bruch’s membrane

Question 29

what are the functions of the retinal pigment epithelium?

Answer 29

absorb light, pigment resynthesis and phagocytosis

Question 30

what would occur if the retinal pigment epithelium lost it’s phagocytotic ability?

Answer 30

blindness secondary to cellular debris

Question 31

which type of photoreceptor receives vertical information?

Answer 31

cones

Question 32

what is the path of vertical information?

Answer 32

photoreceptor
bipolar cell
ganglion
AP
optic nerve

Question 33

which type of photoreceptor receives horizontal information?

Answer 33

rods

Question 34

what is the path of horizontal information?

Answer 34

horizontal cells to bipolar

amacrine cells to ganglion

Question 35

what is the optic papilla?

Answer 35

depression in the retina that marks the entry and exit point for the optic nerve

Question 36

what is the lamina cribosa?

Answer 36

where the optic nerve traverses the choroid

Question 37

what is the blood supply to the retina?

Answer 37

central retinal artery and vein, end artery so blockage = blindness

Question 38

how far do retinal vessels extend into the retina?

Answer 38

to the middle limiting membrane of the outer plexiform layer, retinal also gets oxygen from nearby choroid vessels

Question 39

what is the fovea?

Answer 39

site of highest visual acuity, only contains cones, also called macula

Question 40

what is the structure of the fovea?

Answer 40

depression in the retina, all retinal layers above the outer nuclear membrane are stripped away for greater visual acuity

Question 41

describe the choroid

Answer 41

contains melanocytes, vascular tissues, loose CT

Question 42

describe the capillaries of the choroid

Answer 42

fenestrated, supply retina

Question 43

what is the ora serrata?

Answer 43

separates anterior retina and posterior retina

Question 44

describe tarsal glands

Answer 44

secrete sebum to prevent tear evaporation

Question 45

describe wolfring glands

Answer 45

accessory lacrimal glands

Question 46

describe glands of zeis

Answer 46

sebaceous glands that are assoc with hair follicle and secrete sebum into eyelash

Question 47

describe glands of moll

Answer 47

apocrine sweat glands