eye

Question 1

Three layers of eye

Answer 1

fibrous tunic = sclera and cornea
Vascular tunic/ uveal tract = ciliary body, iris choroid
neural = retina and pigmented layer

Question 2

What are the neural and pigmented layer of the retina

Answer 2

neural = photoreceptors, ganglion cells, bipolar cells
pigmented layer = melanin

Question 3

Chambers of eye

Answer 3

vitreous
posterior
anterior
anterior and posterior chamber form the aqueous humour
* iris separates anterior and posterior chamber

Question 4

Posterior chamber

Answer 4

between iris and lens

Question 5

anterior chamber

Answer 5

between cornea and iris
supplies the lens and cornea with oxygen and nutrients

Question 6

What is the vitreous humour and its function

Answer 6

Composed of water, mineral salts and mucoprotein
maintains pressure in eyeball to prevent it collapsing on itself

Question 7

What are the extrinsic muscles of the eye

Answer 7

Attach at the sclera
medial rectus, lateral rectus, superior rectus, inferior rectus

superior oblique and inferior oblique

Question 8

Purpose of lateral rectus and its cranial nerve supply

Answer 8

rotates eyeball outwards
abducent nerve

Question 9

purpose of medial rectus and its cranial nerve supply

Answer 9

rotates eyeball inwards
oculomotor nerve

Question 10

purpose of superior rectus and its cranial nerve supply

Answer 10

rotates eyeball upwards
oculomotor nerve

Question 11

purpose of inferior rectus and its cranial nerve supply

Answer 11

rotates eyeball downwards
oculomotor nerve

Question 12

purpose of inferior oblique and its cranial nerve supply

Answer 12

rotates eyeball upwards and outwards
oculomotor nerve

Question 13

purpose of superior oblique

Answer 13

rotates eyeball downwards and outwards
trochlear nerve

Question 14

What is the ciliary body

Answer 14

consist of ciliary muscle and secretory epithelial cells
attached to the lens by suspensory ligaments

Question 15

function of the ciliary body

Answer 15

produces aqueous humour
change lens thickness

Question 16

How do ciliary muscles change lens shape

Answer 16

Contraction of muscles cause suspensory ligaments to loosen so lens gets thicker = for near vision

Relaxation of muscles cause suspensory ligaments to tighten so lens gets thinner

Question 17

What nerve controls the ciliary muscle

Answer 17

the parasympathetic branch of the oculomotor nerve
When stimulated, it causes ciliary muscles to contract

Question 18

myopia vs hyperopia

Answer 18

myopia = short sightedness
hyperopia = far sightedness

Question 19

what causes hyperopia

Answer 19

Can’t see nearby objects

eyeball shorter than usually so light not refracted properly

require convex lens

Question 20

what causes myopia

Answer 20

Shortsidedness when can’t see far objects

eyeball is too long

Requires biconvex lens

Question 21

How is intraocular pressure created

Answer 21

created by the aqueous humour in anterior chamber.
pressure maintained as the rate of secretion by epithelial cells matches the rate of drainage into the venous system through the venous sinus

venous sinus found between iris and cornea

Question 22

What is glaucoma and how is it caused

Answer 22

condition where the optic nerve is damaged caused by build up of intraocular pressure and causes blurred vision

Question 23

What is the flow of tears

Answer 23

tears are excreted by the lacrimal gland into the excretory lacrimal duct

Tears drain into the superior and inferior lacrimal canaliculi and drain into the nasolacrimal duct which will drain tears into nasal cavity

Question 24

what is the anterior cavity of the eyeball split into

Question 25

Function of pupil

Answer 25

control the amount of light entering eye so that vision is clear Dim light = widen to activate photoreceptors bright light = constrict to not damage retina

Question 26

Nervous control of the pupil

Answer 26

Iris contains radial and circular antagonistic muscle pairs controlled by autonomic nervous system radial controlled by sympathetic nerves that cause pupil to widen circular controlled by parasympathetic causing pupil to constrict

Question 27

function of lens

Answer 27

Biconvex body that will change thickness to refract light onto the retina

Question 28

How does the eye change to see near objects

Answer 28

lens becomes thicker to focus = increases refractory power pupils constrict convergence

Question 29

Function of retina

Answer 29

Receives light and converts into a nerve impulse

Question 30

What is the macula of the retina

Answer 30

near the centre of the posterior portion of retina. It is the yellow spot It contains an indent which is the fovea (a spot where cones are highly concentrated)

Question 31

Function of fovea

Answer 31

area of greatest visual acuity/ resolution on retina

Question 32

What types of cones are there

Answer 32

long = red medium = green short = blue due to the different amino acid chain of the opsin

Question 33

What are the photopigments in rods and cones

Answer 33

both contain rhodopsin In the cones, it is called photopsin

Question 34

Where is the rhodopsin found

Answer 34

attached to membrane of vesicles present in cones and rods

Question 35

What happens to rods in the presence of light

Answer 35

rhodopsin bleached opsin activates series of membrane bound reactions ending in the hydrolysis of the cyclic nucleotide leading to cation channels on the outer segment of rod to close Na+ being pumped out of the inner segment cant come back in through outer segment Makes it difficult for rod to be depolarised (as it's hyperpolarised) so glutamate not released

Question 36

Rod vs cones

Answer 36

Rod = more abundant, found on periphery, more sensitive to light so used in black and white vision, slow recovery Cones = found at centre (in fovea), detect colour, fast recovery Similarity = contain rhodopsin

Question 37

What is the blind spot

Answer 37

axons of ganglion cells converge to form the optic nerve

Question 38

Layers of the retina

Answer 38

Pigmented layer neural layer retinal blood supply

Question 39

what is the neural layer composed of

Answer 39

photoreceptor cell layer outer synapse layer bipolar cell layer inner synapse layer ganglion cell layer

Question 40

visual pathway

Answer 40

optic nerve (cranial nerve 2) consist of the nasal nerve and temporal nerve Nasal nerves cross at the optic chiasm The optic tract will go to their corresponding hemisphere to the primary visual area in occipital lobe

Question 41

What is the optic tract

Answer 41

the nasal and temporal nerves left visual field = nasal of left eye, temporal of right eye This goes to right hemisphere = right optic tract as it goes to right hemisphere right visual field = temporal of left eye, nasal of right eye Goes to left hemisphere = left optic tract

Question 42

Which cranial nerve controls contraction of the iris muscles

Answer 42

Parasympathetic branches of oculomotor nerve controls ciliary muscle

Question 43

What artery supplies the eye

Answer 43

opthalamic artery (branched from the carotid artery) which branches - the central artery being the most important one

Question 44

What are the veins of the eye

Answer 44

superior and inferior opthalamic vein

Question 45

what is the optic disc

Answer 45

blind spot that does not contain rods or cones

Question 46

Which photoreceptor is more sensitive

Answer 46

rod vision is more sensitive than cone vision