Eye Flashcards
what secretes aqueous humour
ciliary bodies
structures through which light passes
cornea aqueous humour pupil lens post chamber vitreous humour retina (rod and cone cells)
conjunctiva
thin mucous membrane lining on post of each eye lid
covers sclera
contains goblet cells
function: lubricates eye via mucus and tears
immune surveillance and prevents microbial entry
sclera
attachment for the extraoccular eye muscles that move the eyeball
a fibrous, protective outer layer of eye containing collagen and elastic fibres
iris
fibres under autonomic control
control diameter and size of pupil
divider between ant. and post. compartments
can be used to identify people
circular fibres
constrict the pupil and reduce light entering
radial fibres
dilate the pupil
circular muscle of iris
sphincter pupillae
parasym from oculo
radial muscle of iris
dilator pupillae
sym from sup. cervical ganglion
ciliary muscle within ciliary body
parasym from oculo
contraction of ciliary body
makes lens rounder focusing vision on neared objects
relaxation of ciliary body
lens flattens to focus on distant objects
where does reabsorption of the aqueous humour occur?
ciliary body
drained by the canal of schlemm (jxn between the sclera and iris) and returns to the venous system
glaucoma
problems with aqueous humour drainage
increases corneal and intra-ocular pressure
can damage optic nerve leading to progressive, irreversible loss of vision
functions of choroid layer of eye ball
dark pigment that absorbs light and reduces reflection
highly vascular - nourishes outer layer of retina
regulates retinal heat, assists in controlling intraocular pressure`
what is cataracts?
cloudy patches in lens that make vision blurred/misty
the retina
posterior compartment of eye
contains photoreceptors, also, first and second order neurons of visual pathway
the retinal layers
outer pigment layer
multilayered neural layer
rods
more numerous b/w vision low acuity peripheral retina decreases in number towards macula
cones
fewer colour vision high acuity only cones in fovea more abundant at macula
bipolar cells
1st order neurons of visual path
interneuron (horizontal)
horizontal fibres
modulate transmission
interneurons (amacrine)
modulate ganglion cell activity
long horizontal on more superficial layer
ganglion cells
2nd order neurons of visual pathway
how to demonstrate blind spot to individual with normal vision
X and O on piece of paper
close one eye and move closer to it
should disappear and reappear
papilloedma
optic disc swelling
sign of: raised ICP
arise from: optic sheath is continuous with subarchnoid space. increased pressure is transmitted through optic nerve - retinal ganglion cells of optic disc become engorged and bulge anteriorly
what can cause swelling of optic disc?
optic neuritis optic neuropathy accelerated hypertension diabetic papillopathy space occupying lesion of optic nerve head
the macula lutea
lateral to the optic disc
yellow pigmented zone
centre of macula lutea is the fovea
how is the fovea specialised?
only cones present at fovea
retinal avascular zone - light sensed without dispersion/loss
cones cells at most efficient packing density - hexagonal mosaic
which layer supplies retinal cells?
choroid
detached retina
retina begins to pull away from the blood vessels that supply it.
w/o quick treatment can lead to blindness - dark curtain vision
