Exam 1 Koh- Aqueous Humor 1 Flashcards Preview

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Flashcards in Exam 1 Koh- Aqueous Humor 1 Deck (82)
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31

Water transport is _____ based on an _____ gradient

Bidirectional, osmotic

32

What is the aquaporin structure?

28 kD tetramer, each subunit consists of 6 TM helices with 2 short helices

33

Short helices form a major portion of the ___ of an aquaporin

Pore

34

Inner part of the pore of an aquaporin excludes _____ species including ____

Charged, H+

35

What enzymes attack reactive oxygen species?

Catalase, superoxide dismutase, and glutathione peroxidase

36

What is the amount of ascorbic acid in the AH?

0.6- 1.5 mM, 10-50x higher than in the plasma

37

Ascorbic acid in a diurnal mammal is ___x higher than in nocturnal mammals

20

38

Ascorbic acid is actively transported from what?

Stroma to posterior chamber via Na+- dependent- vitamin C transporter

39

What types of antioxidants are in the AH?

Enzymes, ascorbic acid, glutathione, Cys, Uric acid and tyrosine

40

How much glutathione is in the AH?

An important tripeptide, 1-10 micometers (plasma

41

What does glutathione do?

Removes excess H2O2, reactivates ascorbate, serves as a substrate in enzymatic conjugation from blood lens, and cornea

42

What are 3 molecules in the AH?

Glucose, urea, and inositol

43

Glucose makes up what percentage of plasma?

70

44

Glucose passes across the ciliary epithelium by ____ _____

Facilitated diffusion

45

Glucose is _____ of insulin and ______ in diabetes

Independent, increases

46

Urea makes up what percentage of plasma?

85

47

Urea moves _____ across membranes and is a ____ _____ for glaucoma

Passively, hyperosmotic agent

48

What is inositol important for?

Phospholipid synthesis in anterior segment

49

Concentration of inositol in AH is how many times that in plasma?

10

50

How is oxygen important in the AH?

From blood supply, corneal endothelium uses aqueous oxygen, the lens and endothelial lining of trabecular meshwork also use aqueous oxygen

51

The lens contributes what percentage of total bicarbonate?

3

52

What determines aqueous pH (7.5-7.6)?

Relative proportions of CO2 and HCO3-

53

Why is CO2 continuously lost from the aqueous?

Diffusion across the cornea into the tear film

54

Proteins are what percentage of plasma?

1

55

How much protein is in aqueous and plasma?

0.02 mg/100mL, plasma 7 mg/100mL

56

The ___ ___ can secrete proteins directly

Ciliary body

57

What types of proteins are in the AH?

Albumin and transferrin account for 50%, local Igs via iris lymphocytes or plasma cells, small amounts of local fibronectin

58

How many nonredundant proteins are in the AH?

676

59

What is pigemented epithelium derived factor?

Secreted by ciliary nonpigmented cells, a serine proteinase inhibitor, exhibits neuroprotective activities on neurons

60

What do growth factors do in the AH?

Proliferation, differentiation, functional viability, and wound healing; perform diverse, synergistic or opposite biological activities