Lecture 21 & 22: the eye

Question 1

define sclera

Answer 1

outermost cover of the eye

Question 2

what is the episceral layer of the sclera

Answer 2

outer layer
loosely arranged collagen and elastic fibers
highly vascularized
attached the lining of the eyelid (conjunctiva) to sclera

Question 3

what is the sclera proper

Answer 3

located in sclera
made of interlacing collagen fibers
attachment site for tendons of extrinsic eye muscles

Question 4

define lamina cribosa

Answer 4

perforated disc of sclera

pass through the optic nerve fibers

Question 5

define limbus

Answer 5

junction between sclera and cornea

Question 6

what is the posterior of the sclera continuous with

Answer 6

dural covering of the optic nerve

Question 7

define cornea

Answer 7

anterior continuation of sclera

Question 8

what type of epithelium is in the cornea

Answer 8

stratified, nonkeratinized squamous epithelium

Question 9

what is bowmans membrane

Answer 9

acellular layer that separates epithelium from stroma

Question 10

what is the corneal stroma

Answer 10

thin layers of ordered arrays of collagen fibers

Question 11

what is descements membrane

Answer 11

acellular, separates stroma from endothelium

Question 12

what is included in the vascular tunic

Answer 12

choroid, ciliary body and iris

Question 13

define choroid

Answer 13

extends anterior to ora serrata of retina

Question 14

what forms the choriocapillar network and what is taht

Answer 14

choroid

contains small blood vessels that supply cell of retina

Question 15

what is bruchs membrane

Answer 15

acellular fused basal laminae of choriocapillaris and pigmented retinal eptithelium

Question 16

define ciliary body

Answer 16

wedge-shaped expansion of choroid peripheral to the lens and covered by double layer of cells

Question 17

define iris

Answer 17

located anterior to the lens and separates the anterior and posterior chambers and surrounds pupil.

Question 18

what epithelium is in the iris

Answer 18

inner layer: pigmented epithelial cells

outer layer: radially oriented myofilaments

Question 19

what is the pigmented ring of the eye

Answer 19

iris

Question 20

define the retina

Answer 20

photosensitive region that lies posterior to the ora serrata

Question 21

define optic disc

Answer 21

region on posterior aspect of eye where optic nerve excises (no photosensitive retina and constitutes blind spot)

Question 22

define fovea centralis

Answer 22

area in retina that contains only cone-type photoreceptors

Question 23

what are the chambers of the eye

Answer 23

anterior: posterior to cornea and anterior to iris
posterior: posterior to iris and anterior to lens
vitreal: posterior to lens, contains vitreous body

Question 24

where is the pigmented layer of the retina located

Answer 24

adjacent to choroid

Question 25

what is the external limiting membrane of the retina

Answer 25

area at junction and outer segments of rods and cones and outer layer includes adherens junctions between rods and cones and mueller cells

Question 26

what is the outer layer of the retina

Answer 26

cell bodes of rods and cones (1st order neurons)

Question 27

what is the outer plexiform layer of the retina

Answer 27

areas of synapses between axons of rods and cones and dendrites of bipolar neurons and horizontal cells

Question 28

what is the inner nuclear layer of the retina

Answer 28

cell bodes of bipolar cells (2nd order neurons), horizontal cells, amacrine cells and mueller cells

Question 29

what is the inner plexiform layer of the retina

Answer 29

area of synpases betweens axons of bipolar cells and dendrites of ganglion cells

Question 30

what is the ganglion cell layer of the retina

Answer 30

cell bodies of ganglion cells (3rd order neurons)

Question 31

what is the optic nerve layer of the retina

Answer 31

axons of ganglion cells

Question 32

what is the internal limiting membrane of the retina

Answer 32

terminations of mueller cell processes and their basement membrane (support cells)

Question 33

what are the cells of the retina

Answer 33

bipolar, horizontal, amacrine, mueller, ganglion

Question 34

define bipolar cell

Answer 34

conducting nuerons that synapse with rods and cones

Question 35

define horizontal cells

Answer 35

interneurons that interconnect rods and cones with each other and with bipolar cells

Question 36

define amacrine cells of retina

Answer 36

interneurons that connect gangion cells and bipolar neurons

Question 37

define mueller cells

Answer 37

neuroglialc cells that extend through the retina and form external limiting membrane via zonulae adherens between mueller cells and rods and cones

Question 38

define ganglion cells

Answer 38

conducting neurons whose axons form the fibers of the optic nerve

Question 39

define macula lutea

Answer 39

yellow region surrounding fovea, highest visual acuity

Question 40

define fovea centralis

Answer 40

depressing of cone cells

Question 41

define optic disc

Answer 41

lacks photoreceptors, point where ganglion cells turn into optic nerve (tract)

Question 42

what do rods use as photopigment

Answer 42

rhodopsin

Question 43

what do cones use as photopigment

Answer 43

iodopsins

Question 44

what are the discs like in rods

Answer 44

discs attach from cell membrane and become free | constantly renewed

Question 45

what are discs like in cones

Answer 45

discs remain attached to cell membran

Question 46

what type of vision, lamellae, and sensitivity do rods have

Answer 46

black and white not continuous lamellae sensitive to low intensity lightg

Question 47

what type of vision, sensitivity, and lamellae do cones have

Answer 47

color high intensity sensitivity continuous lamellae

Question 48

define bleaching

Answer 48

disassembly of rhodopsin into opsin and retinal after light stimulation

Question 49

define capsule of lens

Answer 49

insertion point for suspensory ligament glycoproteins and type 4 collagen secreted by subscapular epithelial cells

Question 50

define the anterior epithelium of the lens

Answer 50

simple cuboidal epithelial | gives rise to cells that become lens fibers

Question 51

define the lens nucleus

Answer 51

composed of lens cells that mature into fiber like stucture devoid of nucleus and organelles filled with crystalline proteins

Question 52

what are the 2 types of glands in anterior surface of the eyelid

Answer 52

zeiss: sebaceous glands associated with eyelids moll: sweat glands, ducts open into eyelash follicles

Question 53

define palpebral fascia

Answer 53

fibrous core of eyelids | meobomian glands: secretion keeps normal tear film in eye

Question 54

define palpebral conjunctiva

Answer 54

stratified columnar or squamous epithelium with goblet cells lines inner surface of the eyelids continuous with bulbar conjunctiva (covers eyeball)

Question 55

what are the 3 tunics of the eye and what are the structures associated with each

Answer 55

fibrous: sclera, cornea vascular: choroid, ciliary body, iris inner: retina