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Oc Physio > OcPhysioT2_MS > Flashcards

OcPhysioT2_MS Flashcards

1
Q

What is the range of IOP?

Average?

A

Range: 10-22mmHg
Avg: 15.5mmHg

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2
Q

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

A

Nope.

It is skewed to the right.

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3
Q

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

A

2.5%

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4
Q

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

A

Stiffer corneas

THere is a linear relationship.

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5
Q

What does a higher Young’s Modulus correlate to?

A

It corresponds to a steeper slope.

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6
Q

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

A

cornea biomechanical properties.

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7
Q

What are the long term factors affecting IOP?

A 
Genetics
Age
Sex
Refractive error
Race
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8
Q

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

A

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

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9
Q

What structure absorbs some amount of IOP?

A

The uveal tissue. absorbs 2mmHg

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10
Q

What is the total percentage of water in the lens?

A

66%

This amt is lower compared to other tissues

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11
Q

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

A

80%
63%
68%

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12
Q

Does the water content change as you age?

A

Nope

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13
Q

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

A

Increases

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14
Q

What percentage of the lens is proteins?

A

33%

Crystallins makes up 90% of that 33%

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15
Q

What is the significance of proteins in lens?

A

Refractive properties

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16
Q

What are the three types of crystallin proteins?

A

alpha-crystallin
Beta-crystallin
gamma-crystallin

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17
Q

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

A

Cortical region

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18
Q

Describe the concentration of AA in the lens?

A

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

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19
Q

What properties allows AA concentration to decrease in the lens?

A

Aging
Cataract formation
Reduction in Na+/K pump

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20
Q

What happens to AA with aging?

A

Racemization

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

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21
Q

What is the most abundant free AA in the lens?

A

Taurine

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22
Q

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

A

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

23
Q

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

A

The nuclear region

24
Q

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

A

Potassium

25
Q

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

A

Sodium
Chloride
Calcium (50X less)

26
Q

Which inorganic ions increase in cataract formation?

A

Sodium

Calcium

27
Q

Which inorganic ion decrease in cataract formation?

A

Potassium

28
Q

Does the level of magnesium change in cataract formation?

A

Nope, it does not change.

29
Q

Does the lens have a blood supply?

A

No

30
Q

Where does the lens acquire its nutrients?

A

Aqueous humor.

31
Q

What is the oxygen consumption of the lens?

A

Low

32
Q

Who uses the most oxygen in the lens?

A

Epithelium
Then cortex
then the nucleus

33
Q

Which process derives the most energy in the lens?

A

Glycolysis

Oxygen tension around the lens is low.

34
Q

Which energy process generate free radicals?

A

Oxidative phosphorylation

35
Q

What percentage of ATP generated is used for protein synthesis?

A

10%

Also used in synthesis of glutathione

36
Q

Where does 90% of proteins energy go to?

A

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

37
Q

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

A

80%

Yields 2 molecules of ATP

38
Q

What is the rate limiting factor in glucose metabolism?

A

Levels of hexokinase.

39
Q

Does the levels of hexokinase decrease or increase with age?

A

It decreases with age.

40
Q

What does the anaerobic pathway allow the lens to do?

A

REmain transparent in the absence of oxygen.

41
Q

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

A

Epithelium.

Has the enzymes and oxygen content.

42
Q

What percentage of glucose is made from Kreb’s?

A

20%

43
Q

What percentage of glucose is derived from Hexose MOnophosphate shunt?

A

14%

44
Q

What are pentoses used in?

A

Nucleic acid synthesis

45
Q

What is NADPH needed for?

A

Maintenance of GSH

Cofactor in Sorbitol pathway

46
Q

WHat does the sorbitol pathway utilize?

A

NADPH

Aldose reductase

47
Q

How can sorbitol be detrimental to lens?

A 
Predisposition to cataracts
Does not diffuse out of lens fast.
Water flows in
Swelling
Reduction in transparency.
48
Q

Where is sodium most concentrated in the lens?

A

In the posterior cortex

49
Q

Where is potassium most concentrated in the lens?

A

IN the anterior cortex.

50
Q

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

A

In the epithelium, beneath the anterior capsule.

51
Q

Where does the production of aqueous humor come from?

A

Ciliary body of nonpigmented epithelium cells. .

52
Q

What is diffusion?

A

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.

53
Q

What does FIck’s law describe?

A

The net movement of a substance across a semipermeable membrane.

Oc Physio (7 decks)

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