Chapter 11 - Posterior Segment - Anatomy

ashleyr2's version from 2018-01-16 06:55

Section 1

Question Answer
what is vitreous made out of? (5 things)99% water, type II collagen, type IX collagen, mucopolsaccharides, and hyalonric acid
what's the volume of vitreous in average eye?4 cm3
whats a vitreous base?portions of vitreous that attaches to peripheral retina and pars plana
hows the dimensions of the vitreous base in relation to ora serrata?6mm width - 2mm anterior and 4 mm posterior to ora serrata
what does vitreoretinal junctions arise from?arise from footplates of Muller's cells at ILM
where does the vitreoretinal junction provide firm attachments? (8 places)1) vitreous base 2) macula 3) optic nerve 4) retinal vessels 5) edge of lattice degenration 6) chorioretinal scars 7) degenerative remodeling 8) enclosed ora bays
where are the weak attachments of vitreoretinal junctions? (3 places)1) fovea 2) disc 3) lattaice

Section 2

Question Answer
name the 9 laters of the neurosensory retina (inner refers to proximal or vitreous side of retina)1) internal limiting membrane 2) retinal nerve fiber layer 3) ganglion cell layer 4) inner plexiform layer 5) inner nuclear layer 6) outer plexiform layer 7) outer nuclear layer 8) external limiting membrane 9) photreceptor layer
what is the ILM made out of?ILM is made out of foot processes of muller's cells (PAS positive basement membrane)
is ILM true or false BM?ILM is a true basement membrane
small yellow-white spots at ora serrataGunn's dots = ILM
what is the retinal nerve fiber layer made out of?unmyelinated ganglion cell axons and also contains glial cells (astrocytes)
where does myelination by oligodendrocytes occur?lamina cribosa
where does the unmyelinated ganglion cell axons (that made of the RNFL) synapse?axons synapse with nuclei of cells in LGB
whats the distrubuted of cells in ganglion cell layer? (periphery vs middle)single cell layer with cells packed tightly near optic disc and more scattered in periphery
whats the inner plexiform layer?synaptic processes btw bipolar and ganglion cells as well as amacrine with bipolar cells
which arteries supply the outermost layer of the innter plexiform layer?retinal arteries
whats the outermost retinal layer?inner nuclear layer
what supplies the inner 2/3 of the retina?retinal vasculature
what supplies the outer 1/3 of the retina?choroids
what 4 cell bodies are found in the inner nuclear layer?contains cell bodies of 1) bipolar 2) amacrine (confined to inner surface) 3) horizontal (confined to outer surface 4) mullers (spans from ILM to ELM cells
whats the outer plexiform layer?synaptic processes btw photoreceptors and dendritic processes of BIPOLAR CELLS
what makes up the outer nuclear layer?photoreceptor cell bodies and nuclei
where does the most cone nuclei lie?lies in single layer immediately internal to ELM
whats the role of the external limiting membrane?interconnects photoreceptors cells to mullers cells
which is a true BM: ILM or ELM?ILM (true BM) and ELM (false BM)
what makes up the photoreceptor layer?rods and cones
where is 11-cis retinal coverted to all-trans retinol?in PR outer segments (NOT in RPE where it is converted back)
what percentage does rods make up of photoreceptors?rods account for 95% of photoreceptors
where in the retina are there NO RODS?no rods in the center of the fovea
how many million rods are there?120 million rods
where is the density of rods maximal?rod density maximal in a ring of 20-40 degrees around the fovea
how many million cones are there?6 million cones
where does 50% of the cones reside?50% of cones in the macula
name the 3 types of visual pigment of cones1) S = short wavelength sensitive = BLUE (2%) 2) M = middle wavelength sensitive = GREEN (33%) 3) L = long wavelength sensitive = RED = 65%
where is the maximal density of cones?cones density maximal in the focea
whats the difference btw cone disks and rod disks?cone disks are attached to cell membranes and undergo membranous replacement vs. rod discs are not attached to cell membranes
which provides high acuity? cones or rodscones
what makes up the peripheral retina?peripheral retinal extends from macula to ora serrata

Section 3

Question Answer
area of retina where ganglion cell layer is more than 1 cell thick (5-6 mm in diameter)macula
where is the macula located?centered 4 mm temporal and 0.8 mm inferior to optic nerve
at what age does differentation of macula occur?4-6 months old
which 2 cones are predominantly in the macula?red and green cones in the macula
where in the retina has high levels of carotenoids?in the macula - there are high levels of carotenoids 100-1000x more than anywhere else
what is the fovea?central depression of inner retinal sufrace (1.5 mm in diameter) within the macula
whats the diameter of the fovea?1.5 mm in diameter
what is the floor of the fovea made up of?floor of fovea is made up of specialized muller cells in inverted cone shape (muller cell cone)
whats the foveola?central area of fovea?
whats the diameter of the foveola vs fovea?foveola = 350 um, fovea = 1500 um in diameter
what 3 things are absent in the foveola?absence of ganglion cells, nucleated cells, and NO RODS
what 3 things prevent foveal detachment?1) microvilli of RPE which surrounds tips of photoreceptors 2) vicous mucopolysaccharides whihc bathe photoreceptors and RPE 3) IOP

Section 4

Question Answer
name the 2 types of blood-retinal barriersinner and outer barriers
what makes up the inner barrier of the blood retinal barrier?tight junctions (zonula occludens) btw retinal vascular endothelail cells
what makes up the outer barrier of the blood retinal barrier?tight junctions btw RPE cells
which layer: flame or splinter hemorrhagesuperficial = blood tracks along RNFL
which layer: DBHdeep = blood contined by axons oriented perpendicular to Bruchs membrane
which layer: boat-shaped?sub ILM (hemorrhagic detachment of ILM) or sub-hyaloid (blood btw ILM and posterior hyaloid)
which layer: dark hemorrhagesub-RPE
what type of cells make up the RPE?MONOLAYER of hexagonal cells with apical microvilli and basement membrane at base adherent to each other by system of tight junctions or terminal bars that make up blood retinal barrier
what type of arrangement foes RPE and outer segments of photoreceptors have?apex-apex arrnagement (resulting in potential subretinal space)
what are the major functions of RPE?1) helps develop photoreceptors embyrogenesis 2) involved in vitamin A cycle 3) provides nourishment for OUTER HALF of retinal cells 4) receives waste products - phagocytoses photoreceptor outer segments 5) froms outer blood-retinal barrier (tight junctions btw RPE cells) 6) secretes BM material (deposits on inner basal lamina of bruchs membrane) 7) produces melanin granules in 6th week of gestation 8) melanin helps absorb execess light, heat exchange, light absorption

Section 5

Question Answer
name the 5 layers of bruchs membrane 1) basement membrane (inner basal lamina of RPE) 2) collagen 3) elastic tissue 4) collagen 5) basement membrane (outer basal lamina of choriocapillaris
what 2 things are continuous with the pigmented ciliary epithelium?RPE and bruchs membrane
phagocytic cells of the CNSmicroglia
cell of origin for meningiomaarachnoidal cells
which neuroglial cells produce melanin in the CNS?oligodendrocytes
which neuroglial cells produce melanin in peripheral nervous system?schwann cells
branching neural cells in the retina and CNSASTROCYTES
cell of origin for optic nerve gliomaastrocytes
where does the choroid extend?ora serrata to optic nerve
what 2 things is the choroid derived from?derived from mesoderm and neuroectoderm
how thick is the choroid anteriorly and posterior?0.1-0.15 mm thick anterior and 0.22 mm thick posteriorly
what are the 4 layers of the choroid?1) bruchs membrane 2) choriocapillaris 3) stroma 4) suprachoroidal space
whats the blood supply of the choroid?blood supply from 1-2 long and 15-20 short posterior ciliary arteries from internal carotid to ophthalmic artery
whats the major source of nutrition got RPE and outer retinal layers?choroid
which veins drain the choroid?vortex veins to superior and interior ophthalmic veins

Section 6

Question Answer
what pigment in red coneserythrolabe (Red sensitive)
what pigment in green coneschlorolabe (green sensitive)
whiat pigment in blue conescyanolabe (blue sensitive)
whats the peak sensitivity in: red cones560 nm
whats the peak sensitivity in: green cones530 nm
whats the peak sensitivity in: blue cones420 nm
which cones: short wavelegthblue cones = short = 420 nm
which cones: middle wavelengthgreen cones = middle = 530 nm
which cones = long wavelengthred cones = long = 560 nm
whats the pigment in rodsrhodopsin
whats the peak sensitivity in rods505 nm