Exam 1 Remington- Cornea Flashcards Preview

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Flashcards in Exam 1 Remington- Cornea Deck (123)
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61

What does corneal puncture do?

Stimulates BM adhesion

62

Epithelial replacement is _______

Constant

63

Where does cell division occur in the corneal epithelium?

Basal layer

64

The basal cells in the corneal epithelium is replenished from what?

Stem cells in the limbus

65

How do cells move in epithelial replacement?

Basal layer to wing cell layer to surface, barrier function maintained

66

Where are surface cells sloughed?

Into tear film

67

What is the cellular composition of Bowman's layer?

Dense irregular CT, acellular

68

Bowman's layer is considered a ______ layer

Transition

69

How is Bowman's layer compared to the stroma?

Smaller and less regular fibers than stroma

70

Bowman's layer is produced _____ and cannot be _______

Prenatally, regenerated

71

What is a pterygium?

Conj invades corneal tissue, Bowman's layer is lysed

72

What is another name for stroma?

Substantia propria

73

What is the cellular composition of stroma?

Regular dense CT, collagen fibrils, fibroblasts, ground substance

74

What is lamellae?

Bundles of collagen

75

What is the orientation of lamellae?

Fibers are parallel to surface

76

What is the extent of fibers for the lamellae?

Fibers extend from limbus to limbus

77

The _____ stroma has a higher incidence of cross liniing among collagen fibers than ______. Why?

Anterior, posterior. Creates more rigidity helping to maintain corneal curvature

78

What are two names (same cell) for the cells in stroma?

Fibroblasts= keratocytes

79

What junctions are fibroblasts joined by in the stroma?

Gap junctions (can get between cells quickly)

80

What is ground substance composed of?

Proteoglycans and glycosaminoglycans (GAGs)

81

What do proteoglycans so?

Increase tensile strength

82

What are GAGs?

Negatively charged side chains

83

Are GAGs hydrophilic or hydrophobic?

Hydrophilic

84

What do GAGs do?

Maintain component spacing

85

What is the theory of transparency?

Light should pass straight through the cornea, scattered light causes glare

86

How are fibers arranged in the theory of transparency?

Fibers arranged in a regular lattice pattern

87

_____ interference occurs in the theory of transparency

Destructive

88

What is reduced in the theory of transparency due to destructive interference?

Light scattering is reduced, as long as the distance between different refractive indices is less than 1/2 wavelength of light

89

What is the relationship between destructive interference and light scatter?

Inverse

90

When does the cornea lose transparency?

If the spacing is disrupted