Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

OPTO 3002 > eye structure > Flashcards

eye structure Flashcards

1
Q

describe Lens

A

Transparent biconvex. Has capsule, epithelium and fibers.
Posterior surface fits onto anterior viterous face in the hyaloid fossa.
Constant growth through life.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

describe Function of lens

A

Accommodation, UV filtration / absorption, separates vitreous chambers. Nutrition via diffusion from humors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

describe Lens points of interest

A 
Anterior pole (apex of ant. Surface)
Posterior pole (apex of pos. surface)
Lens axis (line connecting the poles)
Equator (circumference and zonule attachment)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

describe Lens capsule

A

elastic collagen membrane. Thick equator, thin poles. Zonule attachment point. Barrier for large molecules.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

describe Lens Epithelium:

A

Singular cuboidal only under ant. Lens.
Secrets / transports nutrients.
Germinative zone(equator): columnar for division/differentiation into fibers and lens cortex
Central zone: stable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

describe

Lens fiber generation

A

Nucleus: earliest (embryonic, feoetal)
Cortex: later formed fibers (5/day)
Sutures: where fibers meet (ant. Y / pos. lander). Tight packing via interlocking interdigitations to allow motion and rigidity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

describe Lens crystallins:

A

Lens fibers produce crystallins following nuclei loss.
High-packing density and RI proteins with variable density (most in nucleus)
Alpha (large)
Beta (common)
Gamma (uncommon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

describe Lens zonules

A

Suspensory ligaments, from ciliary body to capsule. Allows accommodation.
Fibrillin glycoproteins = strength / elasticity
GAG + Hyaluronan = viscoelasticity
3 bands of connection: anterior, posterior, equatorial.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

describe Accommodation

A

Distant focus: ciliary relaxed, zonules taught lens is flat
Near focus: ciliary contracts moving forward, zonules relax, lens thickens in center.
Occurs with convergence / pupil constriction via parasympathetic CN 3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

describe presbyopia due to lens formation

A

Continued fiber formation = larger, thicker, less pliable less
Amplitude of accommodation (max acco) decreases.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

describe Lens transparency with age

A

Maintained with regular arrangement, avascular and lack of tissue / organelles.
Age has accumulation of metabolic products, osmotic / oxidative stress, crystallin aggregation, disruption of arrangement = increased light scatter (CATARACT)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

describe Cataract causes

A 
Age
Congenital (from birth)
Induced/toxic (steroids)
Metabolic (diabetes)
Radiation/trauma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

describe Viterous humor structure

A 
4/5 eye volume
Between lens and retina
Central viterous = more liquid
Cortical viterous = more gel
Mostly water with come hyalocytes, RI = 1.334
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

describe

Viterous humor function

A

Space filling and shape of eye
Supports position of lens and retina
Stress absorbtion on retina
Maintains optical transparency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

describe Viterous humor landmarks

A

Hyaloid fossa: depression in lens
Ant/pos hyaloid membranes: dense collagen near /opposite to ciliary
Viterous base: strong viterous attachment to pars plana (retina side of ant. Hyaloid membrane)
Hyaloid canal: canal for hyaloid artery lost 6/52 before birth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

describe Viterous humor attachment

A 
Collagen network adhesion. 
Strong adhesion located at:
Viterous base at pars plana and ora serrata
Pos. lens capsule
Macula
Optic nerve head margin
Retinal vessels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

describe Viterous change with ag

A

Viterous change with age
Liquid proportion increases, leads to floaters.
Causes separation between posterior hyaloid face and retinal ILM:
Clean = pos. vitreous detachment and weiss ring
Tractional = retinal tears and vitreous hemorrhage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

describe Retina structure

A

fibrous: cornea(thin), Sclera (thick)
vascular: Uveal tract = choroid, ciliary body, iris
Sensory: retina and optic nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

describe Embryonic retina formation

A

Derived from neuroectoderm. Infoldings of optic cup has retina on inner layer with retinal pigment epithelium on outer layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

describe Sensory envelope:

A

Retina / optic nerve.
Lamina vitrea separates retina from choroid
Retinal pigmented epithelium noureshes photoreceptors
Retina contacts viterous at Inner limiting membrane
Retina extends to ora serrata (ciliary body)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

describe 9 layers of retina + RPE. Outermost to innermost

A 
*retinal pigmented epithelium
Photoreceptor layer
Outer limiting membrane
Outer nuclear layer
Outer plexiform layer
Inner nuclear layer
Inner plexiform layer
Ganglion cell layer 
Nerve fiber layer
Inner limiting membrane 
(Then viterous)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

describe Retinal pigmented epithelium structure

A

Single layer of tight junction cuboidal hexagonal cells from ON to ora serrata, where it continues as pigmented epithelium layer of CB.
Basal RPE anchors to Bruch’s membrane (separates from choroid)
Apical surface has microvilli (more contact with photoreceptor)

23
Q

describe Retinal pigmented epithelium function

A

Absorbtion of light via melanin
Turnover of vitamin A material and visual pigment
Phagocytosis of outer segments of photoreceptors
Active transport of nutrients from choroid to photoreceptor (no passive due to tight junctions)
Acts as blood retina barrier

24
Q

describe Outer/external limiting membrane

A

OLM/ELM is formed by cytoplasmic condensation between photoreceptors and glial cells

25
Q

describe Outer nuclear layer

A

ONL formed by cells bodies and nuclei of photoreceptors.
Rods for night/colorless vision
Cones (RGB) for color and detail
Cones:rods = 1:20

26
Q

describe Photoreceptor cell layer

A

Outer segment: contact RPE. Light sensitive, have discs of pigment
Inner segment: houses mitochondria / organelles. Adjacent segments are insulated by muller cells for conductivity.
Cell body/nucleus: located in outer nuclear layer of retina.
Terminal synapses in outer plexiform layer

27
Q

describe Cones vs rods and synapse names

A

Cones shorter and thicker, dense in fovea.
Rod synapse = Spherule
Cone synapse = Pediele

28
Q

describe Photoreceptor discs

A

Contained in invaginations of cell membrane via discs.
Cone discs are continuous with membrane
Rod discs are stacked w/o membrane connection.
Discs are secreted by inner seg and shed from outer seg, RPE recycle material.

29
Q

describe Visual pigment In retina

A

Rods: Rhodopsin
Cones: S(blue)/M(green)/L(red) opsin
These absorb photons, excite and generate electrical signal.
Excited are recycled by RPE

30
Q

describe Peak wavelength absorbtion for visual pigment

A 
Rod = 500nm
S = 420nm
M = 530nm
L = 560nm
31
Q

describe Rods

A

Very light sensitive, bleached by brightness.
Require low light (scotopic)
All contact 1 ganglion cell = low acuity.

32
Q

describe Cones:

A

Less light sensitive.
Can be in bright (photopic)
Sharp acuity as 1 cone = 1 ganglion cell at fovea

33
Q

describe Color deficiency:

A

Genes for L (red) and M (green) opsins are encoded on X chromosome, defects are recessive.
Genes for S (blue) are autosomal

34
Q

describe Outer plexiform layer

A

OPL transitions from 1st order neurons (photoreceptors) to 2nd order neurons (bipolar cells and horizontal cells) with filled space of muller cell processes.
Outer zone: axons of photoreceptors and axons of muller cells
Inner zone: synapses (rod spherules and cone pedicles)
Thickest at fovea due to pedicle density

35
Q

describe Inner nuclear layer cell bodies

A 
INL contains cell bodies of:
Bipolar cells (BC)
Horizontal cells (HC)
Amacrine cells (AC)
Interplexiform cells (IC)
Muller cells (glial cells)
36
Q

describe Horizontal cells:

A

3 subtypes
- H 1: contacts all types of cones (luminosity)
- H II: input from S (blue) cones (chromaticity)
- H II: input from M and L (green/red) cones (chromaticity)
Integrate information horizontally across retina, dense in fovea.

37
Q

describe Amacrine cells:

A

Only dendrites, receive lateral input from AC and BC, synapse to BC, other AC and ganglion cells with inhibitory function

38
Q

describe Interplexiform cells

A

Receive input from AC, synapse onto AC and BC, send processes to OPL (cone pedicles and BC)

39
Q

describe Bipolar cells

A

2nd order neurons (vertical through path). Ribbon synapses to ganglion cells and AC. Allow spatial vision and color perception.
ON - BC synapse inner IPL
OFF - BC synapse outer IPL

40
Q

describe Muller cells

A

Glial cells spanning entire retinal thickness (outer to in)
Cell body in INL, form passage of neurons and vessels.
Absorb K+/neurotransmitter. Transports nutrients, maintains blood retina barrier.

41
Q

describe Inner plexiform layer

A

Synapse layer, relays visual data between 2nd order neurons (BC), and 3rd order neurons (ganglion).
Synapses called Dyads between BC and ganglion or AC
Absent in fovea

42
Q

describe Ganglion cell layer:

A

Has ganglion nuclei, some AC and branches of vessels with muller cells. Absent in fovea, converys visual data to visual cortex (CNS)
2 types of ganglion cell: midget and parasol

43
Q

describe Nerve fiber layer

A

Axons of ganglion cells form NFL as they run towards ON.
Non-myelinated until lamina cribrosa
Axons arranged in arcades
Superior and inferior ON NFL bindles are thickest
Papillomacular bundle between ON and macular are thinnest.

44
Q

describe Inner limiting membrane

A

ILM has muller cells on the retinal side, and viterous fibrils and GAGs on the outside (hyaloid membrane).
Seperates retina from viterous

45
Q

describe Through pathway

A

1st order - 2nd order - 3rd order
Photoreceptors -> bipolar cells -> ganglion cells
Describes visual pathway

46
Q

describe Lateral modulation

A 
Outer retina (horizontal cells) -> inner retina (amacrine cells)
Describes how visual information is processed before CNS
47
Q

describe Fundus landmarks

A 
Foveola (middle of fovea)
Fovea (middle of macula)
Macula (dense cones)
Retinal artery (light)
Retinal vein (dark)
48
Q

describe Regions in central retina

A 
Macula lutea - central 15 degrees
Fovea - central 5 degree
Foveola - central 1 degree
Umbro - geographic fovea center 
Parafovea - area around macula
Perifovea - area around parafovea
49
Q

describe Fovea centralis

A

Center of macula 5 degree FOV with only cones
Cone axons form band “henle’s fiber layer” (white arcade on fundus)
Blood supply from choroid

50
Q

describe Foveola

A

Center of fovea 1 degree FOV, peak acuity

Only cones and muller cells, thinnest area of retina

51
Q

Describe Geography of peripheral retina

A

Ora serrata : junction between retina and ciliary body

Photosensitive layer collapses to epithelium close to limbus

52
Q

Describe Oxygen supply to retina

A

Central retinal artery (CRA): first branch of ophthalmic artery, capillaries have tight junctions (blood-retina barrier). Supplies inner retinal layers
Choroid: supplies outer retinal layers (photoreceptors / RPS. Branches of short posterior ciliary arteries (SPCA). Fenestrated, but blood retina barrier maintained via Bruch’s membrane and RPE.

53
Q

Describe Blood drainage from retina

A

Central retinal vein (CRV): drains into cavernous sinus or superior ophthalmic vein
Choroidal veins: converge forming cortex veins, draining into ophthalmic veins.

OPTO 3002 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions