Exam 1 Remington- Aqueous Production Flashcards Preview

Anatomy and Biochemisty > Exam 1 Remington- Aqueous Production > Flashcards

Flashcards in Exam 1 Remington- Aqueous Production Deck (25):
1

What is the volume of aqueous in the anterior chamber?

.25 mL

2

What is the volume of aqueous in the posterior chamber?

.06 mL

3

What are the aqueous dynamics?

Secreted by the ciliary processes into the posterior chamber, moves through the pupil into the anterior chamber

4

How does the aqueous production exit from the anterior chamber?

Via trabecular meshwork -> Schlemm's canal or uveoscleral flow

5

What are the 3 factors to be considered as the aqueous is produced by the processes of the ciliary body?

Epithelial membrane, concentration gradient, and passage mechanisms

6

What are the 3 mechanisms by which substances cross the epithelial membrane?

Diffusion, ultrafiltration, and active transport

7

Ultrafiltration

Flow across the epithelium, movement can be enhanced by increasing hydrostatic driving force

8

What is active transport?

A pump mechanism, utilizes cellular energy (ATP) as solutes are moved against a concentration gradient

9

What is the process of aqueous humor formation?

Molecules enter stroma via CB fenestrated caps, ions enter PCE via co-transporters, pumps, and exchangers from stroma, pass into NPCE via gap junctions, ions exit basolateral membrane via channels, co-transporters and pumps, aqueous is produced as these ions and fluid enter the posterior chamber

10

What are the blood-aqueous barrier components?

Fenestrated ciliary body capillaries, ZO in non-pigmented ciliary epithelium, nonfenestrated iris capillaries, tight junctions in posterior iris epithelium

11

Ascorbate is how many times higher in aqueous than plasma?

20

12

Protein is how many times higher in plasma than aqueous?

200

13

Why is the aqueous transparent?

Optically empty, little or no light scatter, no large molecules, Tyndall phenomenon

14

When are cells and flare visible?

In aqueous in disease

15

How do you maintain IOP?

In order to maintain IOP in a relatively small range a constant rate of production of aqueous is balanced by an equal constant rate of exit

16

What 3 factors is inflow dependent on?

Ultrafiltration from BV's in ciliary processes, facility of inflow C_in, and metabolic pump S

17

What is ultrafiltration dependent on?

Hydrodynamic pressure head P_cap- IOP

18

What is facility of inflow C_in dependent on?

Takes into accound the resistance int he tissues through which the aqueous components pass, C_in measured in microliters/min/mmHg, reciprocal relationship between facility and resistance

19

What is the metabolic pump?

Located in ciliary epithelium, remains constant, in not affected by IOP, can be affected by drugs

20

Aqueous outflow is dependent on what 3 factors?

Hydrodynamic pressure head, facility of outflow C_out, and uveoscleral outflow

21

What is the hydrodynamic pressure head?

IOP- P_ev

22

What is the facility of outflow?

Takes into account the resistance through the trabecular meshwork (TM) and juxtacanalicular tissue

23

What is the uveoscleral outflow?

U remains constant (except at high IOP) Inflow=Outflow

24

When does the aqueous production formula hold true?

At low and moderate levels of IOP; slight variations in the factors help to maintain homeostasis

25

What does the formula represent?

A complex equilibrium between rate of formation of the aqueous and the rate of outflow, when the balance is disturbed, the problem is usually a decrease in outflow rather than an increase in production