Test 5
21. Aqueous humor:
a. is mainly produced by the non-pigmented epithelium of the pars 

b. is only produced by active transport mechanisms 

c. is actively extruded into the lateral intercellular channels at a 
    constant rate 

 d. is kept optically clear by the tight junctions between the 
    endothelial cells of the iris capillaries and of the non-pigment 

e. when nascent, is hypertonic compared to anterior chamber 


22. The composition of aqueous humor:

a. is solely dependent on the nature of the freshly secreted fluid 

b. is slightly hypertonic compared to plasma with respect to 
    concentrations of sodium, potassium and bicarbonate 

c. has a very low concentration of ascorbic acid 

d. is lower in glucose concentration, but higher in lactate 
    concentration when compared to plasma 

e. contains low levels of amino acids, but high levels of protein when 
    compared to plasma 

23. Intraocular pressure:

a. remains constant if aqueous production is constant 

b. has a population distribution that is skewed to the right 

c. is decreased when acetazolamide is administered, by decreasing 
    the rate of sodium and bicarbonate transport into the posterior 

d. can be increased by use of long term steroids 

e. is usually measured by indentation at the slit lamp 

24. The vitreous:

a. has an anterior cup known as the lenticular fossa  for the posterior 
    surface of the lens 

b. contains a channel running antero-posteriorly that contained the 
    hyaloid artery, a branch of the central retinal artery, that nourished 
    the lens in utero 

c. is strongly attached to the vitreous base, which extends from the 
    ora serrata to the pars plana 

d. is attached to the posterior lens capsule by Wiegerís ligament 

e. is immediately related to Retinal Pigment Epithelium 


25. The extraocular muscles:
a. are of skeletal type

b. consist of muscle bundles which are made up of many fibres that 
    are approximately 100-300 microns in diameter 

c. are covered in a fibrous sheath called epimysium from their origin 
    to their insertion, that is continuous with Tenonís capsule 

d. take their origin from rhe common tendinous ring 

e. have dense innervation for fine control of eye movements 

To test 6
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