Histology of the Eye

Question 1

Bony Orbit

Answer 1

Where the eye sits

Question 2

Optic Canal

Answer 2

through which nerve leaves muscles enter superficial layer of globe

Question 3

extracellular eye muscle

Answer 3

allow up down/ side mvmt light goes through many structures before retina

Question 4

three layers “tunics” of eye

Answer 4

1) Fibrous Tunic - outermost, with sclera and continuous with the cornea
2) Vascular Tunic - Middle Very vascular as choroid abundant capillary for supply
anterior is cilliary body and iris
3) Neural Tunic - Innermost has retinal pigment epithelium, outer layer and neural retina - inner layer location of neruons and photoreceptors

Question 5

Sclera (all the facts) (funciton, and composition, and things in it)

Answer 5

Fibrous Tunic
White opaque portion of eye composed of Type I collagen with few elastic fibers and fibroblast in a dense connective tissue
Sensory - can tell if eyelas
vascularized by blood vessels
Function - protective envelope and attach to eye muscles

Question 6

Cornea (function and facts)

Answer 6

refraction of light to focus on retina transparent. Avascular gets nutrients from aquous humor and lacrimal fluid
Very very sensitive

Question 7

What are the five layers of the Cornea

Answer 7

Corneal Epithelium - on exterior surface, stratified squamous non keratinized (7 day turnover) highly innervated
Bowmans Membrane - basement membrane
Stroma - largest section with type I collagen elastic and fibroblasts - lamella organized to allow transparency. similar to sclara
Descemets mebrane - basement membrane
Corneal Endothelium - simple squamous

Question 8

Conjuctiva

Answer 8

Mucous Membrane cover anterior sclera and in eyelid
composed of stratified columnar epithelium
contain goblet cells - secrete in to tear

Question 9

Conjunctivites

Answer 9

Is inflammatino caused by a virus or bacteria also can caused by alergens irritints

Question 10

Choroid (funciton, locaiton, composition)

Answer 10

Vascular Tunic Part
Function - Provide Nutrients to retinal pigment epithelium and outer layers of neural retina
note the inner layers are supplied by central retinal artery
location - posterior of vascular tunic
composition - loose connective tissue
Is pigmented and absorb stray light to prevent interference done by melanocytes

Question 11

Ciliary Body (funciton, composition)

Answer 11

wedge shaped region in anterior
Function - produce aqueous humor and change shape of lens
composition - loose connective tissue, blodo vessela and smooth muscle. Lined with double layer of cuboidal epithelium, one pigmented and one nonpigmented (the outer one) inner is pigmented

Question 12

Ciliary processes

Answer 12

Have fenestrated capillaries that aqueous humor travel and poured into the space

Question 13

Path of aqueous humor

Answer 13

enter posterior chamber, then papillayr aperture, then anterior chamber which is under cornea. And provides nutrients to lens and cornea, then it goes out the canal of schlemm (which is many draining holes)

Question 14

Glaucoma

Answer 14

increase in intracellular pressure when there is compromised blood flow and maybe cant get out

Question 15

Zonule Fiber

Answer 15

Aka suspensory ligament forming the suspension of the lens

this is a part of the ciliary body

Question 16

Accomodation Reflex

Answer 16

decrease tension will buldge more convex the lens to see more near
the relaxation will increase tension lens flattens and see far
Depends on distance you wanna see

Question 17

Iris (3 parts)

Answer 17

function to focus light

1) Lens capsule - basement membrane, completely envelopes lens
2) subcapsular epithelium - cuboidal cells on anterior surface slowly move toward equator and go in to lens
3) Lens fibers - immediately deep to subcapsular. Fill the lens and has lens fibers. With time fill with crystallins

Question 18

Cataract

Answer 18

an opaque lens

Question 19

Vitreious Body

Answer 19

Transparrant gel, fills vitreious cavity behind lens
Give shape 99% water
and collegen and hyaluronic acid

Question 20

Hyalocytes

Answer 20

believed to make the collagen and the acid.

Also we do see phagocytosis in the vitreious body

Question 21

Retinal Pigment Epithelium (shape, function, facts)

Answer 21

cuboidal to columnar cells with basal located nucleus
Function reduce light scatter, and phagocytose membrane shed by photoreceptors
apical side has granules, microvilli and a sleeve extension surrounding the tip of photoreceptor

Question 22

what forms the blood retina barrier

Answer 22

desmosomes zonula occludans and zonula adherens

Question 23

Anatomy of Retina (10 layers from innermost)

Answer 23

RPE (retinal pigment epithelium)
Photoreceptor 
outer limiting membrane
outer nuclear layer (cell body of rods cones)
outer plexiform layer ( synaptic zone)
inner nuclear layer (body of bipolar horizontal and amicrine)
inner plexiform (center synaptic zone)
cell body of ganglion 
ganglion cell axons
inner limiting membrane

Question 24

photoreceptors

Answer 24

absorb photons make potential
Rods for low light monochromatic
cones have three opsins

Question 25

Colorblind

Answer 25

altered gene expression in cone of opsin gene

Question 26

The fovea

Answer 26

Region for increased acuity
v rich in cones
retinal layers missing positioned off to the edge of the fovea

Question 27

The optic Disc

Answer 27

Exit point of ganglion axons
Unmyelinated retinal gangion cells collect at disc and through sclera
Then acquire myelin sheath and form the optic nerve

Question 28

Blind Spot

Answer 28

Created due to no photoreceptors in this area