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75 Cards in this Set
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- 3rd side (hint)
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What is the first and second strongest attachments of the vitreous to the retina?
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Firmest-vitreous base
second firmest-(Ligamentum hyaloide capsulare) or Optic disk |
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What happens to the composition of the vitreous as people age?
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becomes more liquid and less gel. and more soluble proteins in vitreous as we age
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Where does liquidification begin in the vitreous?
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in the central vitreous
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What happens to the collagen in vitreous as we age
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The total collagen amount doesn't change but increase in collagen in the gel component and reduction in liquid
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what happens to Hyaluronic acid in vitreous as we age
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HA conc doesn't change after 20 but the amount in the liqu. increases and the gel HA decreases
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PVD happens in what percentage of people? Do you have to have symptoms?
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70% for 65+
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Macular holes are most prevalent in who?
What causes them? |
elderly women
Shrinkage of prefoveal vitreous cortex |
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Bloodsupply of the retina
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outer 1/3-diffusion from the choriocap form short post ciliary art.
inner 2/3- central ret art. What is the difference between the two? |
outer-high flow and oversupply the retina can only utilize a small amount of O2,metabolites pass
Inner-slow flow, best utilization of O2 |
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Difference between structure of choriocapillaries and ret blood vessels
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chorio- fenestrated
ret vessels-not fen. tight jxn What does this mean |
chorio cap will leak flourescien
leaking in ret photo-due to ret. arteries should |
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Blood vessels in the ciliary body
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Blood vessels in the cil. body. pars plicata and pars plana are fenestrated.
But in the ciliary muscle they aren't!!! |
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Iris blood vessels
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not fenestrated, major and minor art. circle, only minor venous circle
not innervated or surrounded by sm. muscle contracts by PERICYTES |
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Auto regulation of retinal blood flow in eye
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the ret blood vessels and the onh have myogenic and metabolic autoreg of blood vessels but the choroid doesn't
it allows metabolite to still enter even when central ret flow is reduced |
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Visual pigment consists of
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Chromophore and Opsin
LOCATED IN OUTER DISKS (chromophore-> retinal |
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Dark Current
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cGMP bound channels in the outer segment are open in dark.
Na and other cations are transported in while K is transported out -40--50 depolarized (-70=rmp) |
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What happens is levels of cGMP greatly decrease?
How is this caused? |
The channels close and the membrane becomes polarized. Less glutamate is transmitted.
PDE converts cGMP to 5'GMP |
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What is the initial step of phototransduction?
(Initialization) |
photon absorbtion causes the 11-cis retinal to be isomerized in to all trans metarodopsin
R->R* |
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What are the two gains in phototransduction?
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1. R* activates over 100 tranducins.
2. PDE hydrolyzes many cGMP and the rate is set by diffusion |
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What is significant about the two gains in phototrans?
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These two gains cause a very high amplification that make the rods very sensitive even to one photon.
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How is restoration of cGMP controlled?
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1. PDE* hydrolysis
2. Guanylate cyclase (GC) mediated synthesis In dark low Ca conc. so GCAP is formed and inhibits GC |
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Inside of the RPE what is the name of the storage form?
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11-cis-retinal
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What are the fxn of the RPE
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to absorb scattered light, transmit substances between chorio. and ret.
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What does the RPE transport from the blood to the retina
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1. Glucose, GLUT1 and GLUT3
2.all trans ret 3.DHA from liver |
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What does the RPE transport from the retina to blood?
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1. maintains water and electrolytes
Na, K, and Cl and H20 2. Lactic Acid 3. Bicarbonate (NA/HC3O, Na gradient) (an increase in LA increases bicarb.) 4. Phagocytosis of photoreceptor outer pigments 5. secretion of certain factors (immune) |
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How is the transport of water driven from the retina to the choriocapilaries driven across the rpe?
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by active trans of cl from ret to blood
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In the visual cycle,what proteins carry the chromaphore between the RPE and the retina and what form is it in?
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1. from ret to RPE: all trans retinOL bount to IRBP goes in to RPE
2. from RPE to retina: 11-cis retinal is transported attached to IRBP |
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How often is the entire length of the outer segment of a photoreceptor renewed.
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11 days
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6 FXNS of the RPE
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1. Phagocytosis
2. epithelial transport 3. light absorbtion 4. Glia (Phagocytosis) 5. Visual Cycle 6. Secretion |
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Secretion of substances from the RPE is mediated by ________?
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Voltage dependent Calcium Channels
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What are the principle supporting cells of the retina? What is their fxn?
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Mueller Cells, ilm->olm
1.structural support 2.electrolyte homeostasis 3. neuroactive substances 4. Recycle transmitters |
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what 2 transmitters are recycled by the Mueller cells
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glutamate and CA!
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what type of cells are astrocytes derived from
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progenitor cells outside the ret
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Astrocytes fxn. where found?
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NFL and GCL1/4 ILM and in optive nerve. protect bvs
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Microglia
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mononuc. phago.
defence |
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Metabolic processes inside the retina and how glial cells participate?
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Glycolysis is performed inside Mueller glia and than Lactate or alaline
Ox. metab inside photoreceptor Than Glutamate is a waste and is signal to glia cell |
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For metabolism of glucose in ret. what goes from glial cell to PR back to glial?
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1. lactate or alanine goes to PR
2. GLU from PR to glia 3. glia turn to GLN it goes back to PR |
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How do glia regulate bloodvessels dilation?
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their endfoot is in contact with vascular wall of retinal arteries (have sm and endothelium)
Endfoot->**L-Lactate->release of NO endothel/glia->arteolar vasodilation-> increase in ret blood flow |
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What cells produce the precursor to NO and what is it?
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Mueller cells->L-Arginine from glucose
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how is L arginine made in to NO
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l-arginine+O2-NOS->NO +L citrulin
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Mechanism of Glaucoma?
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1. sped up ganglion cell loss -GC suseptibility, aging, high iop, large disk?
2.myopic suseptibility - Connective tissue in optic nerve head, sugessing somekind of altered scleral ridgity deformation of post. 3. weak laminar pores in the outer portions of the lamina cribosa 4.IOP levels 5.low vascular nutrition of the optic disk-poor perfusion- sys. htn, peripheral vasoplasm, PV 6. deficient Autoregulation of blood flow 7. focal areas of filling defects 8. zone between ohn and peripapillary choroid suseptible to ischemia |
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These usually read lower IOPs.
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thinner corneas--myopia
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In descending order, where is the neuroretinal rim broadest
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ISNT
Inferior, superior, Nasal, Temporal |
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Glacoma can lead to what affecting the neuroret. rim.
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neuroret rim loss: it, st, th, ni, ns
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Which is circular the vertical disk or the horizontal cup?
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Neither are circular
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What are the zones in PERIPAPILLARY CHORORETINAL ATROPHY?
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1. alpha (peripherally)-thinning of chorioret area with hypo and hyperpigmentation
2. beta (centrally)-visible scleral and large choroidal vessels 3. sceral ring- inner to beta exaggerated in myopia and tited dics APBC |
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When zone beta completely surrounds the ONH.
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Halo Glacomatosus
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What are the fxns of the conjunctiva?
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movement of eyelids
maitance and drainage of tear film protective fxns-trapping microbes defensive-lymph tisue contol of microflora supplies the corneal epithelial cells *it does all these things with the help of the lacrimal system |
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Distribution of mast cells in the conjunctiva.
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adenoid layer, numorous in conj. stroma, norm. not in epi.
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Which have blood vessels? Papillae or follicles?
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Papilla
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What is produced inside the goblet cells of the conj?
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MUC5AC
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Main neural inputs to conjunct. for goblet cell secretion.
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parasympathetic
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Basal secretion of tears:
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sympathetic inn., sup cervical gang. accessory lacrimal gland
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reflex tear secretion by stimulation of cornea
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cn V parasym. sphengopal. gang.
lacrimal gland PERIPHERAL ORIGIN |
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Light or psychogenic reflex tears
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cortical, brain stem, parasym, spengopal gang.
CENTRAL ORIGIN |
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Tear turnover
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5-6 min.
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basal tear secretion rate
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1.2mL/min
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tear turnover rate
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16% of total tear volume per minute
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total tear film
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7mL
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max capacity of lacrimal lake
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30mL
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What MUC is found most in tears?
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MUC16
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Regulated proteins increase with tear secreation. What are they?
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lactoferrin, lipocalin,lysozyme
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Jones I test. Typical results
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florescein retrieved from through nasal pass. etc. 5 min after
under 45 pass within 6 min average 3 over 45 pass within 12 min avg 6 |
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Jones II Test
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instill florescein in lacrimal lake after 5 min of test I,
1. Dye recovery-NORMAL 2.Recovery of only saline-UPPER SYSTEM IS FAULTY 3. No recovery-COMPLETE OBSTRUCTION |
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partial pressure of the o2 in AH
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55
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Strength stiffness of Bowman's Layer
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the ant 1/3 is much stiffer and stronger due to its woven nature
**Damage usually starts posteriorly and moves anteriorly |
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Polymodal receptors respond to
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mechanical higher temp and chemical
large receptive field-code for intensity and duration |
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Cold receptors in cornea
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small recept. field and respond to amperage
more abundant in the periphery don't respond to heat, basal firing rate short delay, good discrimination threshold |
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mechano-nociceptors
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limited ability to respond to coding of a stimulus
acute sharp sensations |
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Corneal sensitivity
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more in apex less in perifery,
less in morning, the cornea is less sens. j/ b4 menstruation |
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Regeneration of cornea at descemet's membreane and endothelium
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descemet's membrane gets regenerated by endotheial
But damage to endothelial cells doesn't repair |
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Where does Cloquet's Canal come from? Where is it?
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It is formed when the primary vitreous gets compressed by the secondary vitreous.
S shaped optically empty space between mittendorf (ant lens) to bergmeister's papilla at optic disk |
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Vitreous boy composition
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99% water, 1%type II collagen, some soluable protiens, and HA
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The collagen content of the collagen is highest when?
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it is a gel
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Where is the collagen concentrated in the vitreous?
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in the ant
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concentration of phosphates in the vitreous
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Low conc of Phosphates in vit.
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Glucose conc. in vitreous?
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half the amount in vitreous or plasma
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