Test 2: lecture 23: eye Flashcards by jillian Bastidas

where eyelids meet

canthus (medial and lateral)

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sebaceous glands in the eyelid

meibomain gland

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punctae

opening of the meibomain gland in the eye lid

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the opening between the eyelids

palpebral fissure

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the eyelid/conjunctiva is composed of two parts

bulbar conjunctiva covers the globe

palpebral conjunctiva lines the inner aspect of the eyelid

the two parts meet at the fornix

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two muscles of the eyelid

levator palpebrae superioris elevated the upper eyelid and keeps the eyelid open, voluntary

oribularis oculi- closes the eyelids

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the conjunctiva is ___ epithelium and contains large and actively secretory goblet cells that produce mucin component of the pre-corneal tear film

stratified columnar

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3rd eyelid

ocular adnexae (nictitating membrane)

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The vertical bar of the T of the third eyelid is surrounded by the superficial gland of the third eyelid at its base which is a ____ gland that produces an aqueous secretion

tubulo-alveolar

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tear fluid is made by

superficial gland of the third eyelid

lacrimal gland located superotemporal to the globe

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KCS

insufficient tear (keratoconjunctivitis sicca)

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epiphora

overflow of tears secondary to obstruction of the lacrimal duct

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lacrimation

irritation or inflammation

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The ___ keeps the cornea moist

pre corneal tear film (PCTF)

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Tears are drained away from the eye via ___

the nasolacrimal drainage system

lacrimal puncta → canaliculus → lacrimal sac → nasolacrimal duct

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pre corneal tear film is made by

superficial: oily (meibomain gland)
middle: aqueous (lacrimal and 3rd eyelid)
inner: mucoid (goblet cells)

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Three tunics of the eye

outer (fibrous)

middle (vascular)

inner (sensory)

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the outer fibrous chamber of the eye:

cornea- transparent

sclera

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the middle vascular tunic of the eye

uveal tract

anterior- ciliary body and iris

posterior- choroid

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The inner sensory tunic of the eye

retina

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two ocular chambers

anterior and posterior

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space between the anterior face of the iris and the posterior surface of the cornea

anterior chamber

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space between the posterior surface of the iris (anteriorly) and the anterior face of the vitreous (posteriorly)/anterior surface of lens except in pupil area.

posterior chamber

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The junction between the clear anterior part of the fibrous tunic (the cornea) and the opaque caudal part of the fibrous tunic (the sclera) is called the___

limbus.

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The ___ comprises the bulk of the fibrous tunic. In contrast to the cornea, it consists of irregularly arranged collagen fibrils of variable size

sclera

Posteriorly, the sclera is sieve-like in a discrete region, called the area (lamina) \_\_\_\_. The openings in the scleral tunic at this point allow the optic nerve axons (the axons of the ganglion cell layer of the retina) to exit.

cribrosa

cornea has ___ epithelium

non-keratinized stratified squamous epithelium

what makes the cornea transparent?

avascular * non-keratinized stratified squamous epithelium * no pigmentation * collagen fibrils: uniform size and highly ordered embedded in a proteoglycan matrix. Fibrils are produced by stromal cells called keratocytes. * dehydrated stroma 2ry to corneal endothelial function.

the “wettability” of the pre-corneal tear film depends on the mucin layer of the PCT that is secreted by ___ cells. It reduces the surface tension of the tear film and distributes it over the corneal surface.

goblet

cornea

\_\_\_ keeps the cornea dehydrated and allows spacing of collagen fibrils to remain uniform

sodium/potassium ATPase pump

corneal epithelial are attached to the basement membrane by ___ and attached to each other by \_\_\_

laminin E-cadherin

corneal epithelial cells come form ___ where epithelial stem cells generate transient amplifying cells that then migrate over the basement membrane and form basal corneal epithelial cells

limbus

the choroid, ciliary body and iris make up the \_\_\_

middle tunic of the eye- the uvea

the ___ part of the eye is highly vascular, often heavily pigmented and rich in elastic tissue

uvea

the iris is highly vascular, heavily pigmented and composed of \_\_\_arranged connective tissue fibers

loosely

corpora iridica

The amount of ___ pigment present in the iris determines what color the eyes are perceived to be (blue eyes have less pigment and brown eyes have more)

melanin

Blue eyes have no pigment in \_\_\_, but pigment in the \_\_\_

iris stroma iris epithelium

Brown eyes (top right) have pigment in both the ___ and \_\_\_

stroma iris epithelium

Albino eyes lack pigment in iris and other parts of the eye as well, and appear red because the ___ blood vessels are visible.

iridal

non-visual retina =

(pars iridica retinae).

The iris is covered on its posterior surface by an epithelium (the posterior iris epithelium), which – like the ciliary epithelium – is considered to be part of the non-visual retina (pars \_\_\_\_).

iridica retinae

The \_\_\_\_will decrease the size of the pupillary opening when it contracts (miosis) and is innervated by axons of the parasympathetic division of the ANS.

sphincter muscle

The ___ muscle will increase the size of the pupillary opening when it contracts (mydriasis) and is innervated by the sympathetic division of the ANS.

dilator

ciliary body and processes make fluid which go \_\_\_

from the posterior chamber to the anterior chamber and out of the irido-corneal angle

\_\_\_ body make a secretion. The active secretion is based on the enzyme carbonic anhydrase.

Ciliary

Carbonic anhydrase inhibitors are used clinically to reduce intraocular pressure when it is elevated (\_\_\_)

glaucoma

Note that the ciliary epithelium consists of a double layer; the internal layer (close to the vitreous) is ___ while the deeper (external) layer is \_\_\_

not pigmented pigmented

the lens is transparent. Together with the \_\_\_, focuses light on the retina

cornea

The lens is a\_\_\_structure that, along with the cornea and vitreous body, has the anatomical property of transparenc

biconvex

suspensory apparatus of lens

**zonular ligaments** arise near base of ciliary body and course along the ciliary processes to insert at lens equator. These are easily seen in the fixed eye after opening. In histologic sections, the fine zonular ligaments are difficult to see.

\_\_\_ hold the lens in place

zonular ligaments

Contraction of ciliary muscle (circumferential) acts to decrease the ___ diameter of eye in the plane of ciliary processes/lens. This releases tension on the lens which, having inherent elasticity, increases it’s anterior-posterior dimensions. This process is termed “accommodation” and is used in near vision. Most developed in primates.

horizontal

The \_\_\_consists of an enveloping basement membrane (the lens capsule) made up of Type IV collagen, an anterior epithelium and a stroma made up of lens fibers without nuclei (nuclei are lost as the lens fibers differentiate

lens

Where cell division and fiber elongation occur in the lens

only at equator (lens bow region)

The shape of the lens is determined by the \_\_\_capsule, and the tension on the lens by the ciliary body (i.e. ciliary muscle) acting through the zonular ligaments.

elastic lens

In postnatal life, the lens epithelium is present only on the ___ surface of the lens.

The posterior lens epithelium, present in the embryo/fetus, was converted to lens fibers (primary lens fibers) during early prenatal lens development. The primary lens fibers are surrounded by the secondary lens fibers, and form the \_\_\_of the lens. The secondary lens fibers are the cortex of the lens

“nucleus”

The \_\_\_of the eye is that region of the inner posterior portion of the globe that can be viewed using an ophthalmoscope

fundus

The \_\_\_includes the optic disc, retinal and choroidal vasculature, tapetum lucidum and adjacent nontapetal region.

fundus

When viewed during a funduscopic (ophthalmoscopic) examination, the ___ (cellular in dogs and cats, fibrous in horse, cow, sheep) appears triangular in outline with the base of the triangle located in the region of the optic disc.

tapetum lucidum The position of the optic disc in relation to the tapetum can be variable (optic disc does NOT vary in position; the extent of coverage of the tapetum can vary).

In dogs and cats, the tapetal layer is \_\_\_(tapetum cellulosum). In horse, cow and sheep, the tapetum consists of \_\_\_\_(tapetum fibrosum). There are no clinical differences observed between the two forms of tapeta.

cellular connective tissue

retinal ___ are larger in size but fewer in number

venules

retinal arterioles are ___ than venules

small and more numberous

the ___ is the yellow green structure behind the retina and located between the RPE and choroid

tapetum

\_\_\_ have a fibrous tapetum, while ___ have a cellular tapetum

Herbivores carnivores

zonular ligaments come off the ___ and attach to the lens

ciliary body

what side of the lens is thicker

anterior, where the cells are. cells produce type 4 collagen

optic disc is also called

blind spot

\_\_\_ in the eye is semitransparent and has a tapetal zone and a non tapetal zone

retinal

tapetum nigrum

the pigment in the RPE and choroid in inferior quadrant [known as the non-tapetal region

The ____ is the most posterior of the three parts of the uvea

choroid

choroid is highly vascular and lies between the ____ and the sclera.

RPE/retina

An important function of the choroid is to provide nourishment to the ___ layers of the retina which has the highest degree of metabolic activity of any tissue.

outer

The tapetal layer is a choroidal modification located between the large ___ vessels externally, and the ___ internally

choroidal retinal pigment epithelium/choriocapillaris

“Stars of Winslow ”

The openings in the tapetum through which choroidal arterioles pass through are visible with an ophthalmoscope

retina has\_\_\_ layers

10 Retinal pigmented epithelium (RPE) Photosensitive (photoreceptor) layer (rods and cones) External limiting membrane- ELM External (outer) nuclear layer- ONL External (outer) plexiform layer- OPL Internal (inner) nuclear layer- INL Internal (inner) plexiform layer-IPL Ganglion cell layer-GCL Nerve fiber layer-NFL Internal limiting membrane-ILM

at the periphery the RPE will \_\_\_\_

collapse into 1 cell layer of pigmented cells and the other 9 layers will collapse into a layer of non pigmented cells

where retina terminates is called the

ora serrata zone lies between the anterior margin of the retina and the ciliary bodies.