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88 Cards in this Set
- Front
- Back
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What are the 4 accessory structures of the eye?
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The conjunctiva, the eyelids, the lacrimal glands, and the extrinsic eye muscles.
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What is conjunctiva? What is it called relative to it's position on either the eyelid or the eye?
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A stratified columnar mucosal epithelium. On the eyelid it is called palpebral, on the eye itself, bulbar.
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Name the 2 special sebaceous glands in the eyelid.
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The Meibomian glands and the glands of Zeis
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What is the apocrine sweat gland of the eyelid called?
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The gland of Moll.
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Flow chart of tears (that I'm shedding studying this material)
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Lacrimal glands->ducts->puncta->canals -> sac -> nasolacrimal duct
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Contents of tears?
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Salt, mucous, lyzozyme
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The three cranial nerves that ennervate extrinsic eye muscles?
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III, IV, VI
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What are the three tunics of the eye?
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Fibrous, vascular, retinal
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What are the three chambers of the eye?
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Anterior, posterior, vitreous
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What are the refractive media of the eye, from outside to in?
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Cornea, lens, aqueous humor, vitreous humor
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What are the two components of the fibrous tunic of the eye?
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Cornea and sclera.
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What are the three components of the vascular tunic of the eye?
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Choroid, ciliary body, and iris
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What are the three main refractive media in the eye?
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The lens, the aqueous humor, and the vitreous humor
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Divide the retina into two main categories. Where are they located?
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Nonphotosensitive, anterior to oro serrata, and photosensitive, posterior to oro serrata. FUN FACT: The oro serrata is the line between the retina and the ciliary body.
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Characterize sclera by CT and function.
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Dense Type I collagen with fibroblasts. The opaque insertion layer for the extrinsic eye muscles.
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Where do retinal axons pierce the sclera?
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The lamina cribosa
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Where does the sclera join the cornea? What is special about this place?
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The limbus. The canal of Schlemm is here, contained in Fontana spaces, where aqueous humor drains.
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Pierce the cornea (oww) from outside in with a pin. What 5 layers will you hit in order?
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Anterior epithelium, Bowman's membrane, substantia propria, Descemet's membrane, Posterior epi.
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The cornea has 5 layers, what's true about ALL OF THEM.
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NO VASCULATURE. NONE. FORGET IT.
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Classify the anterior epi (layer 1) of the cornea
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Strat squamous nonkeratin epi. Free nerves and microvilli.
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What is Bowman's layer of the cornea made of?
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Type I collagen.
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What is the substantia propria made of?
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Type I and V collagen organized in lamellae
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Characterize the posterior epi of the cornea. What's it's MOST IMPORTANT FUNCTION?
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Simple squamous epi. The Na channel kick out Na and H20, keeping the cornea dehydrated.
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Who supplies nutrients to the fibrous tunic?
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The choriocapillaris in the vascular tunic.
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What does the oro serrata divide in the VASCULAR tunic?
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The choroid, posterior, from the ciliary body, anterior.
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Name the membrane that separates the choroid from the retina?
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Bruch's membrane.
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Is the choroid pigmented? If so, what can you find in the CT?
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Yes, melanocytes.
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What kind of epi layer the ciliary body?
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Simple columnar. Outer is pigmented while the inner is not.
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How do capillaries all over the eye get nutrients to these 400,000 layers?
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Fenestrations. Little tiny holes.
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What does the nonpigmented layer of the ciliary body do?
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Make aqueous humor.
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What anchors the lens in place? Where can you find them?
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Suspensory ligaments of the lens. Ciliary processes.
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What is the fiber found in suspensory ligaments of the lens?
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Fibrillin.
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When the ciliary muscle contracts, what happens to the lens? What is this called?
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It gets convex. Accomodation.
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What is accomodation?
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Near focus.
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What innervates the ciliary muscle?
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Parasyms from III.
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What covers the iris on the outside?
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Incompletely, pigmented cells and fibroblasts.
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What covers the iris on the inside? Why?
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Two layer pigmented epi, so the only light going into the eye goes through the pupil.
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Cells of the dilator pupillae and their ennervation.
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Myoepi, sympathetic.
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Cells of the sphincter pupillae, and their innervation.
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Smooth muscle, parasym.
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Flow chart of aqueous humor, from production to absorption.
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Make by nonpigmented cells on ciliary body --> posterior chamber (iris) --> anterior chamber (iris) --> Canals of Schlemm (limbus).
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What is glaucoma?
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Some blockage of aqueous humor drainage leading to high intraocular pressure.
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If I poked a pin through the lens from front to center, what would I hit? If I did it from the back to center, what would be different?
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The lens capsule, the subcapsular epi, and the lens fibers. There is no subcapsular epi on the posterior surface of the lens
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Do lens fibers (cells) have any nucleii or organelles?
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Nope. Wouldn't they obstruct light, come to think of it?
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What special proteins are in the lens? What do they do?
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Crystallins. Alter the refractive index.
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What is a cataract?
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When crappy stuff accumulates in lens cells that shouldn't be there.
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What is the vitreous humor made of?
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Collagen, some hyaluronic acid, and 99% water.
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Do we renew vitreous humor over time?
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No.
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What embryo remnant is still in the vitreous humor?
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Hyaluronic canal.
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What do the iridial and ciliary retina have in common?
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They are both comprised of two layers of epi each. And of course, they don't absorb light.
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Are both layers of the iridial retina pigmented?
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Yes.
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Are both layers of the ciliary retina pigmented?
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No. The outer is while the inner is not.
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Lots of layers in the eye have an outer pigmented epi and an inner nonpigmented epi. Interesting. What's true for the junctions in these two cell layers, across almost all eye tissue?
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Outer pigmented layers have loose jxns, while the inner nonpigmented do not.
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Is the two-layered epi on the ciliary retina continuous with the two-layered epi on the ciliary body? What does it do?
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Yes. Make aqueous humor, blood-aqueous barrier, anchor zonule fibers.
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The greatest visual acuity in the eye?
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The fovea centralis
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The blind spot?
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The optic disk: Where blood vessels enter and the optic nerve leaves.
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Take a deep breath and stick a pin through the retina from the choroid to the vitreous humor. What 10 things will you hit in order?
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1. Pigment Epi
2. Rods/Cones 3. Outer Limiting Membrane 4. Outer Nuclear Layer 5. Outer Plexiform Layer 6. Inner Nuclear Layer 7. Inner Plexiform Layer 8. Ganglion cell layer 9. Optic Nerve fiber layer 10. Inner Limiting Membrane |
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I say "plexiform" and you think what? (retinal layer)
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Axodendritic synapses HAPPEN HERE.
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I say "nuclear" and you think what? (retinal layer)
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Nucleii, cell bodies ARE HERE
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Melanin moves where and when?
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Daytime: cell processes of pigment epi. Nighttime: apical cytoplasm.
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Characterize the structure of the pigment epi of the retina?
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Tight jxnx, basal infoldings, SER and melanin
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What are the three functions of pigment epi?
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1. esterify Vitamin A
2. phagocytose tips of rods 3. synthesize melanin |
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What are the photoreceptor cells?
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Rods and cones
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Why is "Layer of Rods and Cones" a bad, bad name for the second layer of the retina?
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Because these cells actually only BEGIN in this layer, and stick through the next 3 until they synapse in the Outer Plexiform Layer.
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Rods see what?
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Light at night (low-intensity light)
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The 4 parts of a rod?
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Outer segment, inner segment, outer rod fiber, inner rod fiber
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What's in the outer segment of a rod?
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Rhodopsin in neat little disks
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What's the fate of the rod disks?
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When shed, the pigmented epi eat them.
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What must you remember about the use of "OUTER" and "INNER" in the retinal layers and rod/cone parts?
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Light will hit the INNER layers first, because it's coming through the vitreous humor, not through the choroid. These OUTER layers, and the OUTER segments of rods/cones, are only hit by light after it goes through 8 layers or so. Curiously counterintuitive and I don't like it at all.
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What is rhodopsin?
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A rod membrane protein called OPSIN bound to cis-retinal (Vitamin) A
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Flow chart of photoreception
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Light hits rhodopsin, cis-retinal becomes trans-retinal (BLEACHING) and dissociates -> opsin helps GTP meet transducin -> transducin activates cGMP pdiesterase -> cGMP is broken down -> Na channels close without cGMP -> hyperpolarization inhibits nt release
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What should you remember about photoreception as opposed to other kinds of neuronal activity?
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We think of neurons becoming depolarized and "turning on", eventually firing some neurotransmitter then shutting off. In the eye, Rods/cones ARE FIRING NEUROTRANSMITTER ALL THE TIME except when they see light. Photoreception is kind of like "shutting off" a neuron to indicate "the absence of dark"
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What is the analog to rhodopsin found in cones? What's the difference?
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Iodopsin. Cones can see color, intense light, and details
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What does a cone synapse with?
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A single bipolar neuron.
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What are the disks in cones made of?
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The plasma membrane, invaginating.
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What is the outer limiting membrane?
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The zonula adherens between photoreceptors and glial cells
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What's in the outer nuclear layer?
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The nucleii of rods and cones.
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Who synapses in the outer plexiform layer?
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Photoreceptors to bipolar cells
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What's in the inner nuclear layer?
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The cell bodies of bipolar neurons and a couple of other people I'm not bothering to learn.
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Who synapses in the inner plexiform layer?
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The bipolar neurons to ganglion cells
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What are amacrine and horizontal cells?
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If you are reading this, go get a sandwich. I'm worried you're not eating enough. DON'T STUDY WHAT'S NOT IN BOLD.
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What's in the ganglion cell layer? Except....where?
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Cell bodies of ganglion cells. Not in the fovea centralis.
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What activates the ganglion cells, ultimately?
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Hyperpolarization of photoreceptors.
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What's in the optic nerve layer and what happens here?
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Unmyelinated axons of ganglion cells that get a myelin by poking through the sclera on their way out of the eye.
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What are the intrinsic eye muscles and what is their function?
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The ciliary muscle and the iris. Accomodation and pupil size.
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What is myopia?
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The eyeball is too long and light converges in front of the retina. NEARSIGHTEDNESS
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What is hyperopia?
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The eyeball is squat and light would converge somewhere behind the retina. FARSIGHTEDNESS
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Astigmatism?
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Cornea or lens has a weird curve.
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LASIK stands for?
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Laser-assisted-in-situ-keratomileusis.
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