Eye Flashcards
(136 cards)
1
Q
What is in the aqueous chamber?
A
Anterior chamber, posterior chamber, aqueous humor
2
Q
What is in the vitreous chamber?
A
Region posterior to lens, contains vitreous body that fills the cavity
3
Q
What are the three concentric tunics of the eye?
A
Fibrous tunic, uvea/vascular tunic, retinal tunic
4
Q
What is in the fibrous tunic?
A
Sclera, cornea
5
Q
What is in the uvea/fibrous tunic?
A
Choroid, ciliary body, iris
6
Q
What is in the retinal tunic?
A
Outer pigmented layer, inner neural layer
7
Q
What is the cornea?
A
Transparent structure, lacks blood vessels and lymph, highly sensitive with rich nerve supply
8
Q
What clinical correlate is special regarding the cornea?
A
Easy for transplant with little risk of rejection by hosts immune system due to lack of blood vessels and lymphatics
9
Q
How does the cornea retain moistness from tear film?
A
Microvilli
10
Q
What are the 5 layers of the cornea?
A
Corneal epithelium
Bowmans membrane
Stroma
Descemets membrane
Corneal endothelium
11
Q
What is the corneal epithelium lined with?
A
Stratified squamous non keratinized
12
Q
What are cells attached by in corneal epithelium?
A
Desmosomes
13
Q
What do the nuclei of the corneal epithelium contain?
A
Ferritin, iron storage protein, protects corneal DNA from free radical damage from UV light
14
Q
What does the corneal epithelium have a rich supply of that trigger blinking reflex?
A
Free nerve endings
15
Q
What is the limbus or corenosclera junction?
A
Site when the sclera becomes the cornea, epithelium continues with the conjunctiva epithelium that covers the sclera
16
Q
How do minor injuries of the cornea heal rapidly?
A
Migration of the cells from limbus junction
17
Q
Where are hemidesmosomes present in the cornea?
A
Between basal layer of cells and the underlying basal lamina
18
Q
How is the basal lamina of cornea attached to underlying stroma?
A
Anchoring fibrils
Anchoring filaments
Anchoring plaques
Keratin filaments
19
Q
What is the corneal bowmans membrane?
A
Layer of dense accumulation of interwoven collagen fibrils, connective tissue, *free of cells
20
Q
Can the bowmans membrane regenerate?
A
No, if damaged, vison will be impaired
21
Q
When does the bowmans membrane end?
A
Ends at corneosclera junction limbus
22
Q
What is the function of the bowmans membrane?
A
Provides support to the epithelium, acts as a barrier to spread of infections
23
Q
What is the corneal stroma/substantia propria?
A
Thin lamellae consisting of parallel bundles of collagen fibrils, type 1 and 5 collagen.
Devoid of blood vessels or lymphatics
Between lamellae are sheets of slender fibroblasts called keratocytes
24
Q
What is function of keratocytes in corneal stroma?
A
Produce extracellular ground substance which contains lumican and keratocan
25
What does type 5 collagen and ground substance do for the corneal stroma?
Regulate the precise diameter and spacing of the collagen fibrils
26
Where is the corneal stroma derived from?
Neural crest
27
What is the descemets membrane ?
Type 4 collagen, represents basal lamina to endothelial cells, PAS positive stain
28
What does the descemets membrane separate in the cornea?
The corneal endothelium from the adjacent stroma
29
What does the descemets membrane extend to be, peripherally beneath sclera meshwork?
Pectinate ligament
30
What does pectinate ligament do for the cornea?
Helps maintain normal curvature of cornea
31
What is the cornea endothelium?
Single layer of squamous cells, covers corneal surface that faces the anterior chamber
32
What are cells attached by in the corneal endothelium?
Zonula adherents
Zonula occludens
Desmosomes
33
What do the cells of corneal endothelium contain?
Mitochondria, vesicles, rER and golgi, Na/K ATPase pumps on lateral plasmalemma
34
What is the sclera made up of?
Dense connective tissue, scattered fibroblasts, fine network of elastic fibers and ground substance
35
What are the three layers of the sclera?
Episclera
Sclera Proper
Lamina Fusca/Suprachoroid lamina
36
What is the episclera layer of the sclera?
External layer, loose connective tissue
37
What is the sclera proper of sclera called?
Tennons capsule
38
What is the sclera proper/tennons capsule?
Dense network of thick collagen fibers, dense collagen
39
What is the lamina fusca/suprachoroid lamina of the sclera?
Thin collagen fibers, melanocytes, elastic fibers
Adjacent to choroid
40
What does the conjunctiva cover?
Anterior part of sclera and lines the eyelids
41
When does the avascular cornea stroma transition abruptly to a well vascularized stroma, and corneal collagen fibers merge with those of the sclera?
Corneoscleral junction/limbus
42
Where are the descemets membrane and its simple endothelium replaced with the trabecular meshwork?
At the corneosclera junction/limbus
43
What does the trabecular meshwork merge to form a larger space of in the scleral venous sinus?
Canal of Schlemm
44
What is aqueous humor produced by?
Ciliary processes
45
What is process of aqueous humor drainage?
Aqueous humor leaves ciliary processes and passes through the posterior chamber to get to the anterior chamber, where it passes through the trabecular meshwork into the canal of Schlemm, fluid then enters collecting veins in the sclera
46
What is glaucoma caused by?
Hindrance of drainage of aqueous humor from anterior chamber, can be caused by obstruction of the trabecular meshwork or obstruction of canal of schlemm
47
What are the two types of glaucoma?
Primary open angle
Acute angle closure/closed angle
48
What is primary open angle glaucoma?
Slow process, drainage channels and canal of schlemm get blocked
49
What is acute angle closure/closed angle glaucoma?
Serious with sudden onset of vision loss
Occurs when the iridocorneal angle is more narrow than usual, this obstructs the aqueous humor drainage at the trabecular meshwork
50
What does the middle uveal tunic form?
Forms the pigmented vascularized tunic of the eye, three parts: iris, ciliary body, choroid
51
What is the iris?
Arises from the anterior border of the ciliary body, forms a contractile diaphragm, has a central aperture called the Pupil
52
What does the anterior surface of the iris consist of?
Matted layer of interdigitating fibroblasts and melanocytes, marked with ridges and grooves due to this, no epithelium, exposed to aqueous humor in anterior chamber
53
What does the posterior surface of the iris consist of?
Double layer of pigmented cells: anterior and posterior
54
What does the anterior pigmented epithelium of the posterior surface of iris consist of?
Contractile myoepithelial cells, less heavily pigmented, comprise the dilator pupillae muscle
55
What is the dilator pupillae muscle supplied with?
Sympathetic nerves
56
What does the posterior pigmented epithelium of the posterior surface of iris consist of?
Basal lamina faces the posterior chamber, very rich in melanin granules that protects the interior eye from an excess of light, continuation of the pigment layer of the ciliary epithelium
57
What is the intermediate core of the iris?
Thick core of heavily vascularized connective tissue stroma, contains the sphincter pupillae muscle
58
What is the sphincter pupillae muscle supplied with?
Parasympathetic nerves
59
What is the Ora Serrata?
Marks the anterior limit of retina and choroid
60
What are the radial ridges of the anterior third of the ciliary body called?
Ciliary processes
61
What does the ciliary body stroma consist of?
Two layers:
Outer- smooth muscle called ciliary muscle, contraction changed the shape of the lens
Inner- vascular layer, extends into ciliary processes
62
What is the epithelium of the ciliary body?
Double layer of low columnar pigmented and non pigmented epithelial cells
63
Where is the epithelium of ciliary body derived from?
Two layers of optic cup
64
The epithelial cells directly covering the stroma of the ciliary body contain lots of?
Melanin, corresponds to the anterior projection of the pigmented retina epithelium
65
The surface layer of epithelial cells of the ciliary body lack?
Melanin, continuous with the sensory layer of the retina
66
What are the functions of ciliary process epithelium?
Secretion of aqueous humor
Secretion and anchoring of zonular fibers, forms suspensory ligaments of lens
Major component of blood aqueous barrier
67
What junctional complexes does the blood aqueous barrier have?
Tight junctions between non pigmented epithelial cells
68
Where are the zonular fibers produced from?
Non pigmented cells of the epithelium in ciliary process
69
What is role of zonular fibers?
Anchors the lens in the center of ciliary body
70
What do zonular fibers attach to?
The fibrous ECM of the lens capsule
71
What does the choroid consist of?
Loose, well vascularized connective tissue, numerous melanocytes
72
What is the role of melanocytes in the choroid?
Prevent light from entering eye except through the pupil
73
What are the two layers of the choroid?
Choroidocapillary lamina/Vascular layer
Bruch membrane
74
What is the choroidocapillary lamina/vascular layer of choroid?
Rich microvasculature- important for nutrition to the outer retinal layers
Melanocytes
75
What is the bruch membrane of the choroid?
Acellular, collagen and elastic fibers, thin extracellular sheet between vascular layer and pigment layer of retina
76
Where is the inner tunic derived from?
Inner and outer layer of optic cup
77
What does the retinal pigment layer of the inner tunic attach to?
Attach to bruch membrane and choroidocapillary lamina of choroid
78
What does neural retina layer of inner tunic consist of?
Inner layer, stratified layer with neurons and photoreceptors
79
What does the retinal pigment layer of the inner tunic consist of?
Outer layer, simple cuboidal, junctional complexes, gap junctions, basal folds with associated mitochondria
80
What do the apical ends of the cells in retinal pigment epithelium extend?
Projections and processes that surround the tips of photoreceptors rods and cones and provides support
81
What do the processes in retinal pigment epithelium consist of?
Melanin granules, lysosomes, perioxisomes, and abundant sER
82
What does the sER of retinal pigment epithelium specialize in?
Retinal vitamin A isomerization, and supply it to photoreceptors
83
What is the function of the retinal pigment epithelium?
Absorption of scattered light that passes through neural layer
Tight junctions contribute to form blood retina barrier
Restoration of photosensitivity to visual pigments that were dissociated in response to light
Phagocytosis and degradation of shed components
Removal of free radicals and secretion of GH
84
What does the blood retina barrier do?
Isolated the retina photoreceptors from the highly vascularized choroid, regulates transport of ions between the two compartments
85
What does the neural retina layer consist of?
9 distinct layers
86
What does outer nuclear layer contain?
Cell bodies of photoreceptors
87
What does inner nuclear layer contain?
Nuclei of bipolar cells, amacrine cells, horizontal cells
88
What does ganglionic layer contain?
Neurons with long axons-Ganglion cells
89
What layer do the ganglion cells make up?
Nerve fiber layer and converge to form the optic nerve
90
What does the outer plexiform layer contain?
Axons of photoreceptors, dendrites of associated neurons in INL
91
What does the inner plexiform layer contain?
Axons of connecting neurons in the INL, dendrites of the ganglion cells
92
What does the rod and cone layer contain?
Polarized neurons, photosensitive portions aligned in the retinas rod and cone layer
93
What is the muller cell?
Elongated glial cell, processes extend and span the entire thickness of neural retina
94
What are the functions of the muller cell?
Maintain ionic environment
Provide neurotrophic substances
Remove waste products
Regulate water and ion homeostasis
Regulate blood flow
Form an inter blood retina barrier
95
What are the two boundaries of muller cells?
Outer limiting layer, inner limiting membrane
96
What is the outer limiting layer of muller cells?
Forms a well defined adherent junctions between muller cell and photoreceptor cells
97
What is the inner limiting membrane of muller cells?
Terminal expansion of muller cell processes, cover the collagenous membrane of vitreous body, form the inner surface of the retina
98
What is the ganglion cell layer?
Cell bodies of large multipolar nerve cells, nissl bodies
99
What does the axon of ganglion cell do?
Passes through nerve fiber layer and then into optic nerve
100
What do some ganglion cells serve as?
Nonvisual photoreceptors- detect changes in light quality and quantity during each 24 hour cycle, signals pass via axons of the retinohypothalamic tract to pineal gland, pineal gland secretes melatonin- helps establish bodies circadian rhythm
101
What does the nerve fiber layer contain?
Axons from ganglion cells
102
What are rod cells?
Extremely sensitive to light, function in low light
Secrete rhodopsin
103
What is inner segment of rod cell?
Synthesizes rhodopsin, glycogen, mitochondira, polyribosomes
104
What is outer segment of rod cell?
Flattened membranous discs, storage space for rhodopsin, initiates the visual stimulus
105
What are cone cells?
Less sensitive to light, sensitive to bright light, essential for visual acuity and color vision, most sensitive to green blue and red
106
What is inner segment of cone cell?
Synthesizes iodopsin
107
What is outer segment of cone cell?
Stacked membranous continuous invaginations of plasma membrane , stores iodopsin
108
What is fovea centralis?
Most acute and sharpest vision, very precise visual acuity
109
What does fovea centralis consist of?
Cell bodies of ganglionic and inner nuclear layers are dispersed peripherally, only cone cells in this region, devoid of conducting neurons and capillaries
110
What is macula lutea?
Yellow rim fat deposition surrounding fovea centralis
111
What is optic disc?
Blind spot, where the axons converge to form optic nerve, nerve fibers originate in ganglionic cell layer
112
What is the lamina cribrosa/cribriform plate?
The region of the sclera that contains the openings where the nerve fibers transverse through the sclera
113
What does the lens do?
Focuses light onto retina
114
What does lens contain?
Avascular tissue, highly elastic
Three principal components: Lens capsule, subscapular lens epithelium, lens fibers
115
What is the lens capsule?
Composed of type 4 collagen and proteoglycans, provides attachment to ciliary zonular fibers
116
Where is lens capsule derived from?
Basement membrane of embryonic lens vesicle
117
What is the subscapular lens epithelium?
Single layer of cuboidal cells, present only on anterior surface of lens, epithelial cells divide and provide new cells at the equator, differentiate as lens fibers, allows the lens to grow at equator
118
What are the lens fibers?
Terminally differentiated epithelial cells, cytoplasm becomes filled with proteins crystallin, organelles undergo autophagy, fibers are tightly packed together to form a transparent tissue specialized for light refraction
119
What is lens held in place by?
Ciliary zonular fibers
120
What does ciliary zonule fibers provide?
Process of visual accommodation, permit focusing near and far objects by changing curvature of lens
121
What are the two portions of the eyelid?
Outer cutaneous portion, inner conjunctival portion
122
What is outer cutaneous portion of eyelid lined with?
Stratified squamous keratinized, overlying loose connective tissue dermis and skeletal muscle orbicularis oculi
123
What is inner conjunctival portion of eyelid lined with?
Thin mucus membrane, then conjunctiva
124
What are the tarsal glands?
Sebaceous glands, holocrine section, produces oily layer on the surface of tear film that retards the evaporation of normal tear layer
125
What are the glands of Zeis?
Modified sebaceous glands connected with and empty their secretion onto follicles of eyelashes
126
What are glands of moll?
Modified apocrine sweat glands that secrete lipid that adds to the superficial layer of tear film
127
What are the lacrimal glands?
Tubuloacinar serous glands with myoepithelial cells, produce tears with accessory lacrimal glands
128
What do tears do for conjunctiva?
Keep the surface of conjunctiva and cornea moist and rinse of dust, tears protect the corneal epithelium and contain antibacterial and UV protective agents
129
What does blinking result in?
Gentle compression of the lacrimal gland and release fluid
130
What is lacrimal canaliculi lined with?
Stratified squamous epithelium
131
What is lacrimal sac and nasolacrimal duct lined with?
Pseudostratified columnar ciliated epithelium
132
What are the tears secreted by?
Lacrimal glands
Accessory lacrimal glands
Goblet cells of conjunctiva
Tarsal glands of the eyelid
133
What proteins does the tear contain?
Tear albumin
Lactoferrin
Lysozyme
Immunoglobulin A
Mucins
134
What is the conjunctiva?
Thin transparent mucosa, covers the exposed anterior portion of the sclera and continues as lining on inner surface of eyelids
135
What is conjunctiva lined with?
Stratified columnar epithelium cells with numerous mucus secreting goblet cells (Palpebral conjunctiva)
136
When does the conjunctiva become stratified squamous with goblet cells?
At the corneal rim (Bulbar conjunctiva)
