Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

OPTM 5032 - Ocular Physiology > Aqueous Humor Dynamics > Flashcards

Aqueous Humor Dynamics Flashcards

(71 cards)

Start Studying
1
Q

Three methods of aqueous humor secretion?

A

Diffusion

Ultrafiltration

Secretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When is aqueous humor production greatest?

A

In the morning (2.97 +/- 0.77 microlitre per min)

(8 am - noon)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When is the lowest production of aqueous humor?

A

At night (1.28 +/- ul per min)

(midnight to 6:00 am)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Na+K- ATPase is predominatly bound to?

A

Plasma membrane of non-pigmented epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Na+ ions from the Na+K-ATPase are pushed where?

A

Into the posterior part of anterior chamber to which the water follows

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Aqueous Humor Outflow via Trabecular outflow

A

70-95%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Aqueous Humor outflow via uveoscleral outflow?

A

5-30%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

True or False: Aqueous Humor Outflow and trabecular outflow increase with age?

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Factors that affect IOP: long term

A

Genetics

Age (IOP increases with age)

Gender (M=F 20-40; F > inc. 40)

Seasonal (Winter > Summer) (Weight)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Factors affecting IOP: Short Term

A

Diurnal variations (time of day, higher in the morning)

Postural variations (supine can cause increase)

Exercise (decrease)

Blinking and forceful closure (increase)

Activities causing Valsalver maneuver (exhale with mouth closed)

Eye movements

Food and Drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What kind of fluid was Aqueous Humor considered to be in the early 20th century?

A

Stagnant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why do we need aqueous humor?

A

Shape, Optical Properties

Nourishment to cornea and lens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the refraction of the aqueous humor?

A

1.33332

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Is the aqueous humor vascular or avascular?

A

Avascular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does the aqueous humor have nutrients within it?

A

Since it is avascular the amount of nutrients within the aqueous humor depends on it’s constant turnover.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What else does the constant turnover of aqueous humor do?

A

Wash out metabolic waste products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What do the longitudinal fibers of the ciliary body muscles do?

A

Attach ciliary body to limbus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do the circular fibers of the ciliary body muscles do?

A

Attach to the anterior and inner portions of the ciliary body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What do the radial fibers of the ciliary body do?

A

Connect longitudinal and circular fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the 3 main vessels of the ciliary body?

A

Episcleral circle

Intramuscular Circle

Major Arterial Circle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Where is the Major Arterial Circle and what does it supply?

A

Lies near the iris root; Is the primary supply of the iris and ciliary body

(Paralimbal branch of the LPCA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

The Ciliary Process is supplied by which two branches of the MAC?

A

Anterior ciliary process arteriole

Posterior Ciliary Process Arteriole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is a ciliary process?

A

The functional unit responsible for production of aqueous humor secretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are ciliary processes made of?

A

1) Capillaries
2) Stroma
3) Epithelia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What portion of the ciliary process do the capillaries occupy?
The center of each process
26
What are the two layers of ciliary epithelium surrounding the stroma?
Pigmented and Nonpigmented epithelium
27
What are some functions of Aqueous Fluid?
Source of antioxidants Carries oxygen Maintain globe shape Shock absorption
28
What makes aqueous humor fluid?
Carefully controlled filtrate of blood produced by ciliary body
29
Which chamber of the anterior chamber does the aqueous humor flow into after secretion?
The posterior chamber
30
Where does it go after being secreted into the posterior chamber?
Aqueous humor flows around the crystalline lens and through the pupil to the anterior chamber of the anterior chamber?
31
Does the rate of aqueous humor production follow a pattern?
Yes, it shows a circadian rhythm
32
How much aqueous humor is produced in the morning as opposed to night time?
In the morning there is much more production. (2.97 uL/min vs. 1.28uL/min)
33
Is aqueous humor an active or a passive process?
Active, It works against the concentration gradient
34
What two enzymes are involved in aqueous formation?
Na,K-ATPase (bound to NPE; pushes Na+ into posterior chamber so water follows)) and Carbonic Anhydrase
35
What happens if you inhibit either enzyme?
Decreases aqueous production
36
What are the two pathways in which aqueous humor exits the eye?
Trabecular Conventional
37
Trace the trabecular pathway
Trabecular Meshwork Inner wall of schlemm's canal into its lumen Collector channels Aqueous Veins Episcleral Venous Circulation
38
Trace the unconventional/uveoscleral/posterior route
Iris Root Uveal Meshwork Anterior face of ciliary muscle Through the connective tissue between muscle bundles Suprachoroidal space Sclera
39
What percent of aqueous humor outflows through each pathway?
Trabecular: 70-95% Uveoscleral: 5-30%
40
How does aging affect aqueous humor outflow?
Both total and trabecular outflow decline with age
41
Capillaries of the ciliary processes and choroid are \_\_\_\_\_\_.
Fenestrated
42
How are the RPE, NPE and ciliary processes joined together?
Via tight junctions which create a blood aqueous barrier (Selective to intermediate and high molecular weight substances)
43
Does the endothelia of the inner wall of Schlemm's canal also have tight junctions?
Yes, it prevents the movement of fluid and solutes from the Canal of Schlemm into the trabecular meshwork and anterior chamber
44
The iris and retina do not possess tight junctions/similar epithelia to the blood aqueous barrier but remain impermeable. How?
They have nonfenestrated capillaries
45
IOP is the outcome of what?
Inflow/outflow of aqueous humor
46
If plasma components increase in the anterior chamber IOP will increase or decrease?
Increase
47
How do diseases, trauma or drug induced breakdown of the blood aqueous barrier affect IOP?
Increases IOP
48
How does the eye combat breakdown of the blood aqueous barrier?
Inflow by ultrafiltration is suppressed and thus reduces the rise in IOP This is kown as Pseudofacility
49
How else is IOP rise combatted in the breakdown of the blood aqueous barrier?
Inflammation; possibly interferes with the active transport mechanisms
50
How is IOP measured?
Using a tonometer
51
What is the mean IOP in people ages 10-69?
15.8 with a standard deviation of 2.57
52
What is the IOP magic number?
21 (Mean +2SD)
53
Does IOP increase or decrease with age?
Increase
54
When do females begin to see greater increases in IOP?
Post 40 years of age
55
Does refractive error have anything to do with the pressure of the eye?
NOPE!!!
56
Is IOP greater in the winter or summer?
Winter because people are less active and thus gain weight and increase their BMI
57
What short term factors can affect your IOP?
Diurnal Variations Postural Variations (supine = increase) Exercise (decrease) Forceful closure of eyes (increase) Valsalver Maneuver (exhale with mouth closed = increase) Eye Movements
58
How does Alcohol affect IOP?
Decrease
59
How does caffeine affect IOP?
Slight increase
60
How does Tobacco affect IOP?
May cause transient increase
61
How do Heroine and Marijuana affect IOP?
Decrease
62
What does tonometry do?
Measure pressures
63
What are the conditions of the Imbert-Fick Law?
Perfect Sphere Dry Infinitely Thin (Pretty much impossible)
64
Factors affecting IOP measurements.
Central corneal thickness Corneal curvature Aging IOP effects on cornea Biomedical Properties (Rigidity, Hydration, Elasticity)
65
What is Hysteresis and how is it applied to the eye?
These are visco-elastic materials (like foam matresses); this applies to the eye because the Cornea is also visco-elastic
66
How does corneal curvature affect pressure estimates?
Steeper = overestimate Flatter = underestimate (Not a huge factor)
67
How does Corneal thickness affect IOP estimates?
Thicker = overestimate Thinner = underestimate Not a huge factor
68
How does rigidity affect IOP estimates?
Explains over 17mm of variance
69
What does pulsatile blood flow represent?
It is a calculated value that represents choroidal circulation
70
What is intraocular pressure telemetry used for?
24-hour IOP measurement; helps identify spikes in IOP both short and logn term of various drugs Evaluate clinical efficacy
71
Two types of telemetry
Non-invasive (temporary (contact lens)) Invasive (Permanent implant)

OPTM 5032 - Ocular Physiology (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions