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Mediwizardry > The Eye > Flashcards

The Eye Flashcards

(89 cards)

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1
Q

Which feature distinguishes the optic disc?

A

Absence of photoreceptors; it’s a blind spot.

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2
Q

What is the transparency of the cornea due to?

A

Regular arrangement of collagen fibrils in the stroma.

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3
Q

Where is the lens located in the eye?

A

Suspended behind the iris by the ciliary zonule.

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4
Q

What is the function of goblet cells in the conjunctiva?

A

Produce mucus to lubricate the eye.

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5
Q

Which part of the retina contains the highest density of cones?

A

Fovea centralis.

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6
Q

Which layers of the retina are nourished by the central retinal artery?

A

Layers 6–10.

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7
Q

What are the visual pigments in rods and cones?

A

Rhodopsin in rods, iodopsins in cones.

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8
Q

What is the role of Bruch’s membrane?

A

Separates the choriocapillaris from the retinal pigmented epithelium.

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9
Q

What role does the subcapsular epithelium of the lens play?

A

It gives rise to new lens fibers.

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10
Q

What does the outer limiting membrane consist of?

A

Adherent junctions between Müller cells and photoreceptors.

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11
Q

What is the role of retinal in vision?

A

Light-activated chromophore that triggers signal transduction.

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12
Q

Which photoreceptor adapts quickly to changes in light?

A

Cones.

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13
Q

What muscle constricts the pupil?

A

Sphincter pupillae.

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14
Q

What is the function of the fibrous layer of the eye?

A

Provides mechanical protection and maintains shape; includes sclera and cornea.

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15
Q

What is the primary role of the ganglion cell layer?

A

Contains the cell bodies of neurons whose axons form the optic nerve.

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16
Q

What is the function of the canal of Schlemm?

A

Drains aqueous humor into the venous system.

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17
Q

Which layer of the choroid contains fenestrated capillaries?

A

Choriocapillary layer.

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18
Q

What part of rods and cones contains mitochondria and organelles?

A

Inner segment.

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19
Q

Which cells form the inner limiting membrane?

A

Müller cells.

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20
Q

Which structure controls the amount of light entering the eye?

A

The iris by adjusting the size of the pupil.

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21
Q

How do nutrients reach the cornea?

A

From limbal capillaries, aqueous humor, and tear film.

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22
Q

How do the lens fibers maintain transparency?

A

By eliminating nuclei and organelles and accumulating crystallins.

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23
Q

What is the function of the trabecular meshwork in the limbus?

A

Drains aqueous humor from the anterior chamber to the canal of Schlemm.

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24
Q

Which connective tissue type is found in the corneal stroma?

A

Dense regular connective tissue.

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25
What part of the retina shows no rods?
Fovea centralis.
26
What is the key function of Bruch’s membrane?
Supports exchange between the retina and choriocapillaris.
27
Which part of the eye has no blood vessels and relies on diffusion?
The cornea.
28
What is the significance of the ora serrata?
Marks the transition from photosensitive to nonphotosensitive retina.
29
What is the composition of the vitreous body?
99% water, collagen fibrils, hyaluronate, hyalocytes, and macrophages.
30
Which layers of the retina are nourished by the choriocapillary layer?
Layers 1–5.
31
What kind of secretion is produced by the lacrimal glands?
Aqueous serous secretion with lysozyme.
32
Which layer of the retina contains photoreceptor cell bodies?
Outer nuclear layer.
33
What is the histological characteristic of retinal rods?
Numerous free-floating disks in the outer segment.
34
Which cells secrete the ciliary zonule fibers?
Nonpigmented epithelial cells of the ciliary body.
35
What are the three concentric layers of the eyeball?
Fibrous layer, vascular layer (uvea), and sensory layer (retina).
36
What is the innervation of the dilator pupillae?
Sympathetic nervous system.
37
What is the function of the vitreous humor?
Maintains the shape of the eye and supports the retina.
38
What is the turnover time of the corneal epithelium?
Approximately 7 days.
39
Which cells form the blood-retinal barrier?
Retinal pigmented epithelial cells.
40
How do rods and cones differ in light sensitivity?
Rods are more sensitive to low light; cones are more sensitive to color and high intensity.
41
Which photoreceptor adapts slowly and is more sensitive to dim light?
Rods.
42
What is the innervation of the sphincter pupillae?
Parasympathetic nervous system.
43
What structures suspend the lens?
Ciliary zonule fibers.
44
What is the function of the outer plexiform layer?
Contains synapses between photoreceptors and bipolar/horizontal cells.
45
What is the role of Müller cells?
Provide structural and metabolic support to retinal neurons.
46
What is the histological characteristic of cones?
Outer segments with membrane folds.
47
What type of tissue forms the stroma of the iris?
Loose connective tissue with melanocytes and microvessels.
48
Why is red-green colorblindness more common in men?
Because the genes for red and green pigments are located on the X chromosome.
49
Which layers of the cornea are capable of regeneration?
Epithelium and Descemet’s membrane.
50
What are the most common causes of colorblindness?
Mutations in genes encoding iodopsins or cone-related proteins.
51
What type of photoreceptor is more abundant in the human retina?
Rods.
52
What distinguishes the optic disc from the rest of the retina?
It lacks photoreceptors and is the exit site of the optic nerve.
53
What enzyme in tears provides antimicrobial activity?
Lysozyme.
54
What is the function of Descemet's membrane?
Acts as a posterior basement membrane; regenerates after injury.
55
What are the three main components of the ciliary body?
Ciliary muscle, ciliary processes, and ciliary zonule.
56
Which cells in the vitreous body produce hyaluronate?
Hyalocytes.
57
Which muscle controls lens accommodation?
Ciliary muscle.
58
Which cell type in the retina is involved in color vision?
Cones.
59
How do Müller cells contribute to the inner limiting membrane?
Their basal lamina forms the inner limiting membrane.
60
Where is the aqueous humor located?
In the anterior and posterior chambers of the eye.
61
What are the ten layers of the retina from outermost to innermost?
1. Pigmented layer, 2. Rod and cone layer, 3. Outer limiting membrane, 4. Outer nuclear layer, 5. Outer plexiform layer, 6. Inner nuclear layer, 7. Inner plexiform layer, 8. Ganglionic layer, 9. Nerve fiber layer, 10. Inner limiting membrane.
62
How is the sclera structurally different from the cornea?
Sclera has irregular collagen fibers and is opaque.
63
Which eye structure has a turnover rate of epithelial cells every 7 days?
Corneal epithelium.
64
What is the effect of contraction of the ciliary muscle?
Reduces tension in the zonule fibers, making the lens more spherical.
65
What is the visual pigment found in cones?
Iodopsins (for red, green, and blue light).
66
What happens to lens fiber nuclei during maturation?
They are degraded (autophagy).
67
Which cells produce aqueous humor?
Nonpigmented epithelial cells of the ciliary processes.
68
What enzyme pumps ions to form aqueous humor?
Na+/K+-ATPase in nonpigmented epithelial cells.
69
What retinal layer contains the axons of ganglion cells?
Nerve fiber layer.
70
What is the function of horizontal cells in the retina?
Integrate and regulate input from multiple photoreceptor cells.
71
What pigment is responsible for iris color?
Melanin in melanocytes.
72
What is the total number of layers in the cornea?
Five.
73
What cells conduct visual signals from photoreceptors to ganglion cells?
Bipolar cells.
74
What muscle dilates the pupil?
Dilator pupillae.
75
What is found between the iris and the cornea?
The anterior chamber filled with aqueous humor.
76
What causes glaucoma?
Increased intraocular pressure due to impaired aqueous humor drainage.
77
What is the lens capsule composed of?
Basal lamina secreted by subcapsular epithelial cells.
78
What are the two types of cells in the pigmented epithelium of the iris?
Anterior pigmented myoepithelial cells and posterior pigmented epithelial cells.
79
Which layer of the cornea is responsible for its transparency?
Corneal stroma due to parallel collagen fibrils.
80
What glands are found in the tarsal plate of the eyelid?
Meibomian (tarsal) glands.
81
Where are corneal epithelial stem cells located?
In the corneoscleral limbus.
82
What is the embryological origin of the ciliary epithelium?
It is a continuation of the retinal pigmented epithelium.
83
What is the key functional role of amacrine cells?
Modulate signals between bipolar and ganglion cells.
84
What kind of epithelium covers the anterior surface of the iris?
None; it is covered by fibroblasts and melanocytes.
85
What is the pigmented layer of the retina responsible for?
Absorbing scattered light and regenerating visual pigments.
86
What marks the boundary between the photosensitive and nonphotosensitive retina?
Ora serrata.
87
How is the lens involved in accommodation?
Changes its shape via ciliary muscle tension to focus on near or distant objects.
88
How does the ciliary epithelium participate in the blood-aqueous barrier?
Via tight junctions in the nonpigmented cells.
89
What type of glands are the lacrimal glands?
Serous tubuloacinar glands.

Mediwizardry (6 decks)

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