Eye

Question 1

what secretes aqueous humour

Answer 1

ciliary bodies

Question 2

structures through which light passes

Answer 2

cornea
aqueous humour
pupil
lens
post chamber
vitreous humour
retina (rod and cone cells)

Question 3

conjunctiva

Answer 3

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

Question 4

sclera

Answer 4

attachment for the extraoccular eye muscles that move the eyeball
a fibrous, protective outer layer of eye containing collagen and elastic fibres

Question 5

iris

Answer 5

fibres under autonomic control
control diameter and size of pupil
divider between ant. and post. compartments
can be used to identify people

Question 6

circular fibres

Answer 6

constrict the pupil and reduce light entering

Question 7

radial fibres

Answer 7

dilate the pupil

Question 8

circular muscle of iris

Answer 8

sphincter pupillae

parasym from oculo

Question 9

radial muscle of iris

Answer 9

dilator pupillae

sym from sup. cervical ganglion

Question 10

ciliary muscle within ciliary body

Answer 10

parasym from oculo

Question 11

contraction of ciliary body

Answer 11

makes lens rounder focusing vision on neared objects

Question 12

relaxation of ciliary body

Answer 12

lens flattens to focus on distant objects

Question 13

where does reabsorption of the aqueous humour occur?

Answer 13

ciliary body

drained by the canal of schlemm (jxn between the sclera and iris) and returns to the venous system

Question 14

glaucoma

Answer 14

problems with aqueous humour drainage

increases corneal and intra-ocular pressure

can damage optic nerve leading to progressive, irreversible loss of vision

Question 15

functions of choroid layer of eye ball

Answer 15

dark pigment that absorbs light and reduces reflection
highly vascular - nourishes outer layer of retina
regulates retinal heat, assists in controlling intraocular pressure`

Question 16

what is cataracts?

Answer 16

cloudy patches in lens that make vision blurred/misty

Question 17

the retina

Answer 17

posterior compartment of eye

contains photoreceptors, also, first and second order neurons of visual pathway

Question 18

the retinal layers

Answer 18

outer pigment layer

multilayered neural layer

Question 19

rods

Answer 19

more numerous
b/w vision
low acuity
peripheral retina
decreases in number towards macula

Question 20

cones

Answer 20

fewer
colour vision
high acuity
only cones in fovea
more abundant at macula

Question 21

bipolar cells

Answer 21

1st order neurons of visual path

Question 22

interneuron (horizontal)

Answer 22

horizontal fibres

modulate transmission

Question 23

interneurons (amacrine)

Answer 23

modulate ganglion cell activity

long horizontal on more superficial layer

Question 24

ganglion cells

Answer 24

2nd order neurons of visual pathway

Question 25

how to demonstrate blind spot to individual with normal vision

Answer 25

X and O on piece of paper close one eye and move closer to it should disappear and reappear

Question 26

papilloedma

Answer 26

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

Question 27

what can cause swelling of optic disc?

Answer 27

``` optic neuritis optic neuropathy accelerated hypertension diabetic papillopathy space occupying lesion of optic nerve head ```

Question 28

the macula lutea

Answer 28

lateral to the optic disc yellow pigmented zone centre of macula lutea is the fovea

Question 29

how is the fovea specialised?

Answer 29

only cones present at fovea retinal avascular zone - light sensed without dispersion/loss cones cells at most efficient packing density - hexagonal mosaic

Question 30

which layer supplies retinal cells?

Answer 30

choroid

Question 31

detached retina

Answer 31

retina begins to pull away from the blood vessels that supply it. w/o quick treatment can lead to blindness - dark curtain vision