Physiology: Aqueous Humour Production and Circulation

Question 1

Aqueous Humor

Answer 1

Specialized fluid that bathes the structures within the eye

Question 2

Aqueous Humor purpose

Answer 2

Provides oxygen and metabolites and contains bicarbonate

Bicarbonate- buffers ph produced in cornea and lens by anaerobic glycolysis

Question 3

Production of Aqueous Humor and direction of flow

Answer 3

Produced by an energy dependent process in epithelial layer of ciliary body into posterior chamber of eye

Then flows into anterior chamber and drains to scleral venous sinus through trabecular meshwork and canal of Schlemm

Small amount diffuses through the vitreous being absorbed across the retinal pigment epithelium

Question 4

Organisation of Ciliary Epithelium

Answer 4

Ciliary body and posterior surface of iris are covered by 2 juxtaposed layers of epithelial cells- PE and NPE

Forward continuation of pigment epithelium of retina overlain by an inner non pigmented epithelial layer

Question 5

Ionic Composition ( 5)

Answer 5

1. HCO3- and H+ formed in epithelial cells from hydration of CO2 catalysed by carbonic anhydrase
2. Transported predominantly across basolateral membranes of PE cells into interstitial fluid in exchange for Cl- and Na+ respectively
3. Cl- and Na+ ions diffuse through gap junctions between PE. and NPE cells
4. Transported out of NPE cells into aqueous humour via Na+/K+/2Cl- cotransporter
5. K+ ions leaving the cell are recycled by Na+/K+ pump

Question 6

Outcome

Answer 6

net movement of Cl- and Na+ through the cells from interstitial fluid to aqueous humour is accompanied by water moving through cell water channels (aquaporins) and through paracellular pathway down osmotic gradient by solute movement

Question 7

Components of Human Aqueous humour (Plasma to Aqueous)

Answer 7

Na greater in aqueous 
Cl greater in aqueous 
HCO3 greater in plasma 
Ascorbate greater in aqueous 
Glucose greater in plasma

Question 8

Size of aqueous humour chamber

Answer 8

Posterior chamber= 60ul

Anterior Chamber = 250 ul