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Anterior Segment Disease > Iris and Ciliary Body: Anatomy and Physiology > Flashcards

Iris and Ciliary Body: Anatomy and Physiology Flashcards

1
Q

the uvea

A

-pigmented, vascular middle layer of the eye

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2
Q

three components of the uvea

A

iris, ciliary body, choroid

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3
Q

iris:

  • heavily _____ circular structure
  • _____ in diameter
  • part of the ____, highly ____
A

pigmented;
12 mm;
uvea; vascularized

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4
Q

iris is surrounded by _____;
____ is anterior to the iris;
____ is posterior to the iris

A

aqueous humor;
anterior chamber;
posterior chamber

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5
Q

3 regions of the iris

A

1) iris root
2) pupillary margin
3) collarette

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6
Q

iris root

A

peripheral region of the iris that is continuous with the ciliary body

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7
Q

pupillary margin

A
  • free edge of the iris

- rests on the crystalline lens

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8
Q

collarette

A
  • circular, jagged ridge ~1.5 mm from the pupillary margin
  • attachment site for the fetal pupillary membrane (blood vessels) during embryologic development – vessels fragment and disappear by 8.5 months of gestation
  • divides the iris into 2 zones: pupillary zone, ciliary zone (zones may differ in color)
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9
Q

pupillary zone of iris

A

encircles the pupil

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10
Q

ciliary zone of iris

A

extends from the collarette to the iris root

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11
Q

layers of the iris

A

1) stroma
2) anterior pigmented epithelium
3) posterior pigmented epithelium

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12
Q

iris stroma:

  • most ____ layer
  • composed of: _____
A

anterior;

loose connective tissue, pigmented cells, WBCs, the sphincter muscle, extensions of the dilator muscle

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13
Q

iris stroma: loose connective tissue

  • _____ form a meshwork over the collagen and ground substance
  • collagen fibrils are arranged in _____ (most evident in light colored irises; appear as white fibers)
  • anchor blood vessels (also arranged ____); protect arteries from ____
A

fibroblasts;
radial columns;
radially;
kinking and compression during extensive iris movement

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14
Q

iris stroma: pigmented cells

  • ____ are concentrated just under the meshwork of fibroblasts
  • clump cells: _____ of free pigment within the iris similar to macrophages; concentrated ____
A

melanocytes;
scavengers;
just under the meshwork of fibroblasts in the pupillary zone

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15
Q

iris stroma: WBCs

-involved in ____

A

the immune response

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16
Q

iris stroma: sphincter muscle

  • composed of ____ arranged smooth muscle fibrils in the ____ zone
  • contraction causes ____; pulls the ___ toward the ___
A

circularly;
pupillary;
pupillary constriction (miosis);
pupillary zone; pupillary margin

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17
Q

iris anterior pigmented epithelium:

  • posterior to the ____
  • composed of ____
  • ____ join adjacent cells; regulates passage of ____
A

stroma;
a single layer of pigmented myoepithelial cells;
tight junctions;
aqueous humor from the posterior chamber into the iris

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18
Q

iris anterior pigmented epithelium: dilator muscle

  • arises from ____
  • composed of ___ arranged smooth muscle fibrils in the iris root to a point just below the sphincter
  • forms 3-5 layers that extend into the ____
  • contraction causes ____; pulls the ___ toward the ____; ____ are visible in the ciliary zone
A 
the basal surface;
radially; 
stroma;
pupillary dilation (mydriasis); 
pupillary zone; iris root;
circular contraction folds
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19
Q

iris posterior pigmented epithelium:

  • most ____ layer
  • composed of ____
  • basal surface lines ____
  • apex faces the ____
  • _____ join adjacent cells; regulates passage of ____
A

posterior;
a single layer of pigmented epithelial cells;
the posterior chamber;
apex of the anterior pigmented epithelium;
tight junctions;
aqueous humor from the posterior chamber into the iris

20
Q

the posterior pigmented epithelium with the anterior pigmented epithelium forms the ____; at the ___, 2 layers of epithelial cells curl around from the posterior iris to the anterior surface

A 
pupillary ruff (pupillary frill);
pupillary margins
21
Q

iris blood supply: the ____ supplies the iris;
capillaries in the iris lack _____; contributes to ____; capillary endothelial cells are joined by ____; also contributes to ____

A

major and minor arterial circle of the iris;
fenestrations; the blood aqueous barrier;
tight junctions;
the blood aqueous barrier

22
Q

iris innervation:

  • motor innervation of iris sphincter muscle by ____ fibers
  • motor innervation of iris dilator muscle by ___ fibers
A

parasympathetic;

sympathetic

23
Q

2 iris muscles control the amount of light entering the eye:

  • in bright light, the ____ contracts to constrict the pupil (miosis)
  • in dim light, the ____ contracts to dilate the pupil (mydriasis)
A

sphincter;

dilator

24
Q

pupil diameter varies from ___ to ____ mm

25
Q

melanin production contributes to ____; _____ plays a role in melanin production; ____ increases melanin production; nearly all infants have a _____ iris color; during the 1st 6 months, melanocytes produce more melanin and the iris can ____

A 
iris color;
sympathetic innervation;
UV radiation;
blue or blue-gray;
darken
26
Q

ciliary body:

  • heavily ____, circular structure surrounding the ____
  • part of the ____, highly ____
A

pigmented; lens;

uvea; vascularized

27
Q

outer to the ciliary body is the _____;
inner to the ciliary body are the ____;
anteriorly, continuous with the _____;
posteriorly, continuous with the ____

A

sclera;
posterior chamber and vitreous;
iris, trabecular meshwork, and scleral spur;
choroid and retina

28
Q

transition between the ciliary body and the retina/choroid is called the ____

A

ora serrata

29
Q

pars plicata:

  • wider ____ region
  • 70-80 _____ are located in this region
A

anterior;

ciliary processes

30
Q

ciliary processes are composed of projections of _____; extend into the _____; anterior portion of nonpigmented epithelium produces ____

A

ciliary stroma covered by pigmented and nonpigmented epithelium; posterior chamber;
aqueous humor

31
Q

pars plana:

  • thinner, flatter ____ region
  • extends from the ____ to ____
  • appears ____ in the area of ora serrata
A

posterior;

posterior pars plicata; ora serrata;

32
Q

layers of ciliary body

A
  • nonpigmented epithelium
  • pigmented epithelium
  • ciliary stroma
  • ciliary muscle
  • supraciliaris
33
Q

ciliary body: nonpigmented epithelium

  • most ____ layer that lines the ____
  • single layer of epithelial cells joined by ___; forms a ____; fluid and molecules must pass ____; contribute to ____
  • _____ arise from the basement membrane of these cells; insert into the ____
  • ____ production
A

inner; posterior chamber and part of the vitreous chamber;
tight junctions; complete barrier; through cells, cannot pass between cells; blood aqueous barrier;
zonules;
equatorial regions of the lens;
aqueous humor

34
Q

ciliary body: pigmented epithelium

  • outer to the ____
  • single layer of epithelial cells that are _____ with the nonpigmented epithelium; ____ connect these cells
A

nonpigmented epithelium;
apex to apex;
gap junctions

35
Q

ciliary body: ciliary stroma

-composed of ____

A

vascularized, loose connective tissue (collagen, fibroblasts, ground substance) with melanocytes and WBCs

36
Q

ciliary body: ciliary muscle

  • composed of ____
  • ____ attach to the scleral spur and TM
  • ____ are surrounded by stroma
  • ciliary stroma continues into the ____
A

smooth muscle fibers with longitudinal, radial, and circular orientations;
longitudinal muscle fibers;
muscle fibers;
muscle layers

37
Q

ciliary body: supraciliaris

  • most ____ layer
  • ____ between ciliary body and sclera
  • continuous with the ____
A

outer;
potential space;
suprachoroid (space between choroid and sclera)

38
Q

ciliary body blood supply

  • the ____ supplies the ciliary body
  • capillaries are in the ____
  • capillaries are ____, allows _____
A

major arterial circle of the iris (MACI) supplies the ciliary body;
ciliary stroma;
highly fenestrated; water, molecules, and ions to leak out of the capillaries and enter the stroma

39
Q

motor innervation of ciliary muscle by _____

A

parasympathetic fibers

40
Q

contraction and relaxation of the ciliary muscle controls ____

A

the shape of the lens

41
Q

ciliary processes in the _____ produce aqueous humor

A

anterior nonpigmented epithelium

42
Q
  • aqueous humor is a filtrate of ____
  • consists of ____
  • nourishes the _____ and removes their waste
  • pressure gradient/exerts force on the internal surface area of the anterior eye- called the ____
A

blood;
ions, water, and other molecules that leak out of capillaries in the ciliary stroma;
avascular cornea and crystalline lens;
intraocular pressure (IOP)

43
Q

trabecular drainage of aqueous:

  • _____% of aqueous drains through this route
  • route: _____
A

70-90;
anterior chamber –> posterior trabecular meshwork –> Schlemm’s canal –> aqueous veins and 25-30 intrascleral collector channels

aqueous veins –> episcleral veins

intrascleral collector channels –> intrascleral venous plexus –> conjunctival and episcleral veins

44
Q

uveoscleral drainage of aqeuous:

  • ____% of aqeuous drains through this route
  • route: ____
A

10-30%;
anterior chamber –> iris root –> ciliary body –> supraciliaris –> suprachoroidal space –> vortex veins or absorbed into scleral stroma

45
Q

Anterior Segment OCT (AS-OCT):

  • details of structures above the ____
  • cannot capture structures behind this
  • cannot completely visualize ____
A

pigmented epithelium of the iris;

the ciliary body

Anterior Segment Disease (22 decks)

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