MT2 Info

Question 1

the major nutrients glucose and oxygen are in:

Answer 1

tears, gimbal blood vessels, aqueous humor

Question 2

glucose is not permeable to:

Answer 2

superficial epithelium

Question 3

glucose must get to the cornea via:

Answer 3

aqueous humor

Question 4

glucose uptake across the endothelium must be

Answer 4

facilitated diffusion

Question 5

about how much of the glucose used by the corneal epithelium is metabolized to lactate under normal conditions

Answer 5

65-85%

Question 6

about how much of the corneal glucose is used for aerobic (Kreb’s cycle) and what percent of ATP is produced with this method?

Answer 6

15-35% of the glucose is used to make abut 60-70% of ATP

Question 7

when is more lactate produced?

Answer 7

when the epithelium is made hypoxic (ex: during contact lens wear)

Question 8

when the eye is closed, how does the oxygen flow out?

Answer 8

diffuse out of the palpebral capillaries to the tears

Question 9

oxygen flux from the aqueous to the cornea is especially important when:

Answer 9

the eye is closed

Question 10

oxygen consumption rate is highest in the

Answer 10

endothelium

Question 11

oxygen consumption rate is lowest in the

Answer 11

stroma

Question 12

what % of oxygen is used in the corneal endothelium?

Answer 12

21%

Question 13

what % of oxygen is used in the corneal epithelium?

Answer 13

40%

Question 14

what % of oxygen is used int he corneal stroma?

Answer 14

39%

Question 15

in the open eye, the pO2 is what for tears and aqueous humor?

Answer 15

pO2= 155 mmHg for tears 
pO2= 55 mHg for aqueous humor

Question 16

oxygen tension (P) =

Answer 16

(QX^2 / 2Dk) + BX + C

Question 17

the mathematical determination of diffusion through the lens is called:

Answer 17

Fick’s Law

Question 18

Dk/L represents the:

Answer 18

oxygen transmissibility of the lens

Question 19

how does a lower Dk value of a cL affect oxygen getting to the eye?

Answer 19

decreases oxygen supplied to front of eye

Question 20

how does increased CL lens thickness affect oxygen getting to the eye?

Answer 20

decreases oxygen supplied to front of eye

Question 21

higher Dk/L value= ___oxygen getting through CL

Answer 21

more oxygen

Question 22

what else has an affect on determining oxygen under a CL other than Dk/L?

Answer 22

blinking

Question 23

some studies suggest a minimum Dk/L value for daily wear as:

Answer 23

25

Question 24

some studies suggest a minimum Dk/L value for extended wear as:

Answer 24

85, maybe even 125

Question 25

how many of the tears are refreshed with each blink?

Answer 25

20% of tears

Question 26

what are some affects on cells when they are made hypoxic?

Answer 26

ATP production from mitochondria slows and glycolysis speeds up to try to maintain the ATP supply

Question 27

when the cells become hypoxic and ATP production from mitochondria slows and glycolysis speeds up, what is it called?

Answer 27

Pasteur effect

Question 28

what is the result of the Pasteur effect?

Answer 28

lactate and proton production will increase and glucose consumption will increase

Question 29

what are the factors limiting the rate of glycolysis under hypoxic conditions?

Answer 29

glucose supply, diffusion, glycogen stores

Question 30

in severe hypoxia, what can epithelial cells store and for how long?

Answer 30

they can store glycogen which will last about 2 hours in severe hypoxia

Question 31

corneal epithelial “haze” in hypoxic CL conditions is subjectively described as:

Answer 31

color fringes around bright lights

Sattler’s Veil