Aqueous Humor Dynamics Flashcards
Why do we need aqueous humor?
Provide structure of the globe, nutrition, and refraction of 1.33.
What parts of the eye depend on aqueous humor for nutrition? Why?
Cornea and lens. They are both avascular, need nutrition from somewhere.
Why does aqueous humor have a constant turnover of fluid in the eye?
There are waste products accumulating in the eye. They need to be removed and replaced with fresh nutrients.
What are four things present in the ciliary body?
Muscles, vessels, autonomic nerve terminals, epithelia lining ciliary processes.
What three parts does the ciliary body muscle consist of?
Longitudinal, radial, circular.
Which part of the ciliary body muscle is the transitional muscle?
Radial.
Which part of the ciliary body muscle attaches ciliary body to the limbus?
Longitudinal.
Which part of the ciliary body muscle form anterior and inner portions of the ciliary body?
Circular.
What is the primary blood supply to the iris and ciliary processes?
Major Arterial Circle located in the ciliary body.
How many branches does the MAC supply to the ciliary processes? Which is fenestrated and non-fenestrated?
Two branches.
Posterior:non-fenestrated, anterior:fenestrated.
What is the functional unit responsible for the production and secretion of aqueous humor?
Ciliary process.
What three things does the ciliary process consist of?
Stroma, capillaries, and epithelium.
The two layers of ciliary epithelium surrounding the stroma are?
Pigmented and non-pigmented epithelium.
What is the main source of aqueous fluid in the eye?
Blood through carefully controlled filtration processes.
Aqueous fluid provides a source of what to the corneal endothelium and lens?
Antioxidants.
Why is important that aqueous humor serves as a shock absorber?
If not for aqueous humor, lens would be hitting iris all the time.
Why do the lens require antioxidant?
Lens requires antioxidants to remove free radical in order to stop cataracts developing way to faster than we would like.
The antioxidant in the aqueous humor we speak of is what?
Vitamin C or ascorbate.
Why is calcium removed?
Too much will cause clearly to be decreased and because calcium can cause more cataracts to be generated.
Name 4 things removed in aqueous fluid that can potentially cause problems if not removed?
Calcium, cholesterol, hemoglobin, globulin.
Other than ascorbate, name one other component that is present in the aqueous fluid?
Bicarbonate.
Is it normal to find red blood cells in your aqueous?
No! That’s a problem. Things should not be floating around.
What is the true meaning of “secretion”.
Process by which aqueous humor formation is at its maximum.
What are three processes by which the ciliary process releases its contents?
Diffusion, ultrafiltration, and secretion (80-90%).
During which time is the rate of aqueous humor production largest in a normal individual?
Morning
During which time is the rate of aqueous humor production smallest in a normal individual?
Night time.
Can glaucoma patients have a different circadian rhythm when it comes to aqueous humor production?
Yes.
What two enzymes are responsible for the production of aqueous humor?
Na-K-ATPase and carbonic anhydrase.
Is the aqueous humor production an active process or passive process?
Active. Needs energy to work against its concentration gradient.
Where is Na-K-ATPase located and what is its function?
Predominantly bound to plasma membrane of non-pigmented epithelium. This enzyme helps push the Na+ ions into posterior chamber to which water follows.
Can aqueous humor be altered? As in the amount produced? If so, how?
Yes aqueous humor can be altered depending on the concentration of Na-K-ATPase.
What is the purpose of carbonic anhydrase?
Carbonic anhdrase acts on carbonic acid to produce CO2 and H2O.
If you stop carbonic anhydrase with an inhibitor, what happens to the production of aqueous humor?
No conversation of carbonic acid to water occurs, so no water produced which causes a decrease production of aqueous humor.
What two things are going to help remove aqueous humor from posterior to anterior part of anterior chamber through pupil?
Pressure and anatomical restrictions.
What role does the vitreous humor play for the flow of aqueous humor?
Vitreous humor has glycosaminoglycans that allow it to be a gel like substance. This acts as a barrier and pushes aqueous humor to flow through the pupil.
How many mechanism are involved in removing aqueous humor from the posterior part of the anterior chamber? What are they?
- Conventional route via trabecular meshwork
and unconventional route via uveoscleral pathways.