31. The retinal pigment epithelium:
a. is derived from the outer pigmented layer of the optic cup
neuroectoderm
b. has a basal membrane facing the choroid that allows free
molecular transport between them
c. has an apical membrane thrown into microvillae that surround the
outer segments of the photoreceptors
d. daily phagocytoses 5% of each overlying outer segment
e. produces bilirubin and biliverdin photosensitive pigments via
vitamin A metabolism
32. The neural retina:
a. is made up of 6 cell types
b. contains the first and second order neurones in the visual
pathway
c. contains synapses between photoreceptors and amacrine cells
d. contains an outer limiting membrane formed by fusion between
Muller cells and photoreceptors
e. contains within its outer nuclear layer the cell bodies of bipolar,
horizontal amacrine, interplexiform and Muller cells
f. has synapses between bipolar and ganglion cells within the inner
plexiform layer
g. contains myelinated fibres
33. The photoreceptors:
a. number about 100 per ganglion cell
b. are present in uniform concentration throughout the retina
c. shed most of their discs at night
d. both contain rhodopsin and iodopsin
e. have outer and inner segments joined by a central connecting stalk
which contains a modified cilium
f. differ in their synaptic endings ie. rods have spherules and cones
have pedicles
34. With respect to the photoreceptors:
a. the rods and cones are the first order cells in the optic
pathway
b. they are responsible for conversion of photons of light into neural
signals via their photopigments, namely rhodopsin
and iodopsin in
the rods and cones, respectively
c. they respond to light by depolarising
d. they are maximally depolarised in the dark, also known as the
dark current
e. the extent of hyperpolarisation is dependent on the duration
of the
light impulse
35. With respect to the bipolar cells:
a. they can be sub-divided into villous and invaginating, depending
on their synaptic endings
b. their receptive fields do not tend to overlap
c. they synapse with fewer if associated with cones than when
associated with rods
d. the receptive field size is dependent solely on the number of
photoreceptors to which they attach
e. they hyperpolarise when responding to photoreceptor stimulation