OcPhysioT2_MS

Question 1

What is the range of IOP?

Average?

Answer 1

Range: 10-22mmHg
Avg: 15.5mmHg

Question 2

Does the frequency distribution for IOP follow a normal Gausserian curve?

Answer 2

Nope.

It is skewed to the right.

Question 3

What is the percentage of people who have pressures over 21mmHg?

Answer 3

2.5%

Question 4

Is central corneal thickness effects more pronounced in stiffer cornea or softer corneas?

Answer 4

Stiffer corneas

THere is a linear relationship.

Question 5

What does a higher Young’s Modulus correlate to?

Answer 5

It corresponds to a steeper slope.

Question 6

What is the influence of CCT on IOP measurement dependent on?

Answer 6

cornea biomechanical properties.

Question 7

What are the long term factors affecting IOP?

Answer 7

Genetics
Age
Sex
Refractive error
Race

Question 8

How is blood able to flow through structures in the eye relating to IOP?

Answer 8

The perfusion pressure of the retina, choroid, and ciliary body must be greater than IOP.

Question 9

What structure absorbs some amount of IOP?

Answer 9

The uveal tissue. absorbs 2mmHg

Question 10

What is the total percentage of water in the lens?

Answer 10

66%

This amt is lower compared to other tissues

Question 11

What percentage of water is contained in the capsule?
Dense nuclear region?
Cortex?

Answer 11

80%
63%
68%

Question 12

Does the water content change as you age?

Answer 12

Nope

Question 13

When you have a cataract, does hydration increase or decrease?

Answer 13

Increases

Question 14

What percentage of the lens is proteins?

Answer 14

33%

Crystallins makes up 90% of that 33%

Question 15

What is the significance of proteins in lens?

Answer 15

Refractive properties

Question 16

What are the three types of crystallin proteins?

Answer 16

alpha-crystallin
Beta-crystallin
gamma-crystallin

Question 17

Is the nucleus or cortical region of the lens richer in alpha crystallins?

Answer 17

Cortical region

Question 18

Describe the concentration of AA in the lens?

Answer 18

It is much higher in the lens compared to vitreous, aqueous, plasma.

Question 19

What properties allows AA concentration to decrease in the lens?

Answer 19

Aging
Cataract formation
Reduction in Na+/K pump

Question 20

What happens to AA with aging?

Answer 20

Racemization

The transformation of the L-isomer form to the D-isomer

Question 21

What is the most abundant free AA in the lens?

Answer 21

Taurine

Question 22

What happens when one encounters osmotic stress like Diabetes to taurine?

Answer 22

Down regulation of Na+/taurine cotransport and of AA for GSH biosynthesis.

Question 23

Is the nucleus or cortical region of the lens richer in gamma crystallins?

Answer 23

The nuclear region

Question 24

Name some inorganic ions that are more concentrated in the lens compared to the aqueous?

Answer 24

Potassium

Question 25

Name some inorganic ions that are less concentrated in the lens compared to the aqueous?

Answer 25

Sodium Chloride Calcium (50X less)

Question 26

Which inorganic ions increase in cataract formation?

Answer 26

Sodium | Calcium

Question 27

Which inorganic ion decrease in cataract formation?

Answer 27

Potassium

Question 28

Does the level of magnesium change in cataract formation?

Answer 28

Nope, it does not change.

Question 29

Does the lens have a blood supply?

Answer 29

No

Question 30

Where does the lens acquire its nutrients?

Answer 30

Aqueous humor.

Question 31

What is the oxygen consumption of the lens?

Answer 31

Low

Question 32

Who uses the most oxygen in the lens?

Answer 32

Epithelium Then cortex then the nucleus

Question 33

Which process derives the most energy in the lens?

Answer 33

Glycolysis | Oxygen tension around the lens is low.

Question 34

Which energy process generate free radicals?

Answer 34

Oxidative phosphorylation

Question 35

What percentage of ATP generated is used for protein synthesis?

Answer 35

10% | Also used in synthesis of glutathione

Question 36

Where does 90% of proteins energy go to?

Answer 36

Active transport Cell division Biochem pathways to protect the lens from oxidative damage

Question 37

What is the percentage of glycolysis that takes place in the lens?

Answer 37

80% | Yields 2 molecules of ATP

Question 38

What is the rate limiting factor in glucose metabolism?

Answer 38

Levels of hexokinase.

Question 39

Does the levels of hexokinase decrease or increase with age?

Answer 39

It decreases with age.

Question 40

What does the anaerobic pathway allow the lens to do?

Answer 40

REmain transparent in the absence of oxygen.

Question 41

Does the Kreb cycle take place in the epithelium or endothelium?

Answer 41

Epithelium. | Has the enzymes and oxygen content.

Question 42

What percentage of glucose is made from Kreb's?

Answer 42

20%

Question 43

What percentage of glucose is derived from Hexose MOnophosphate shunt?

Answer 43

14%

Question 44

What are pentoses used in?

Answer 44

Nucleic acid synthesis

Question 45

What is NADPH needed for?

Answer 45

Maintenance of GSH | Cofactor in Sorbitol pathway

Question 46

WHat does the sorbitol pathway utilize?

Answer 46

NADPH | Aldose reductase

Question 47

How can sorbitol be detrimental to lens?

Answer 47

``` Predisposition to cataracts Does not diffuse out of lens fast. Water flows in Swelling Reduction in transparency. ```

Question 48

Where is sodium most concentrated in the lens?

Answer 48

In the posterior cortex

Question 49

Where is potassium most concentrated in the lens?

Answer 49

IN the anterior cortex.

Question 50

Where is the major site of cation transport in the lens?

Answer 50

In the epithelium, beneath the anterior capsule.

Question 51

Where does the production of aqueous humor come from?

Answer 51

Ciliary body of nonpigmented epithelium cells. .

Question 52

What is diffusion?

Answer 52

When a substance is concentrated in one part of the system, the random motions will tend to cause the substance to redistribute itself in time. Does not require energy.

Question 53

What does FIck's law describe?

Answer 53

The net movement of a substance across a semipermeable membrane.