Flashcards in Exam 1 Koh- Aqueous Humor 1 Deck (82)
Water transport is _____ based on an _____ gradient
What is the aquaporin structure?
28 kD tetramer, each subunit consists of 6 TM helices with 2 short helices
Short helices form a major portion of the ___ of an aquaporin
Inner part of the pore of an aquaporin excludes _____ species including ____
What enzymes attack reactive oxygen species?
Catalase, superoxide dismutase, and glutathione peroxidase
What is the amount of ascorbic acid in the AH?
0.6- 1.5 mM, 10-50x higher than in the plasma
Ascorbic acid in a diurnal mammal is ___x higher than in nocturnal mammals
Ascorbic acid is actively transported from what?
Stroma to posterior chamber via Na+- dependent- vitamin C transporter
What types of antioxidants are in the AH?
Enzymes, ascorbic acid, glutathione, Cys, Uric acid and tyrosine
How much glutathione is in the AH?
An important tripeptide, 1-10 micometers (plasma
What does glutathione do?
Removes excess H2O2, reactivates ascorbate, serves as a substrate in enzymatic conjugation from blood lens, and cornea
What are 3 molecules in the AH?
Glucose, urea, and inositol
Glucose makes up what percentage of plasma?
Glucose passes across the ciliary epithelium by ____ _____
Glucose is _____ of insulin and ______ in diabetes
Urea makes up what percentage of plasma?
Urea moves _____ across membranes and is a ____ _____ for glaucoma
Passively, hyperosmotic agent
What is inositol important for?
Phospholipid synthesis in anterior segment
Concentration of inositol in AH is how many times that in plasma?
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
The lens contributes what percentage of total bicarbonate?
What determines aqueous pH (7.5-7.6)?
Relative proportions of CO2 and HCO3-
Why is CO2 continuously lost from the aqueous?
Diffusion across the cornea into the tear film
Proteins are what percentage of plasma?
How much protein is in aqueous and plasma?
0.02 mg/100mL, plasma 7 mg/100mL
The ___ ___ can secrete proteins directly
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
How many nonredundant proteins are in the AH?
What is pigemented epithelium derived factor?
Secreted by ciliary nonpigmented cells, a serine proteinase inhibitor, exhibits neuroprotective activities on neurons