How We See 2

Question 1

Phototransduction?

Answer 1

Conversion of light energy to an electrochemical response by photoreceptors.

Question 2

What are the photoreceptors of the eye?

Answer 2

Rods and cones

Question 3

What do phototransduced rod and cones do?

Answer 3

Activate the optic nerve by generating an action potential

Question 4

What is the visual pigment found in rods?

Answer 4

Rhodopsin

Question 5

What is the visual pigment found in cones?

Answer 5

Opsin

Question 6

Do rods or cones help visualise colour?

Answer 6

Cones

Question 7

Cones help to visualise which three colours?

Answer 7

Red, blue and green

Question 8

What do rods do?

Answer 8

Help to see in dim light

Question 9

What is found within the opsin pigment of rods and cones?

Answer 9

Vitamin A compound

Question 10

Which form does the vitamin A compound takes in rods?

Answer 10

11-cis Retinal

->this is combined with opsin to make rhodopsin i think

Question 11

How does bleaching of the visual pigment result in phototransduction?

Answer 11

Phototransudction cascade

Question 12

What role does Vitamin A play in the visual pigment?

Answer 12

Visual pigment regeneration

Question 13

What happens if you have prolonged vitamin A deficiency?

Answer 13

Rods affected first (because we have more rods than cones).
Rods get bleached and cannot get reformed affecting vision in dim light.

(this lecture was confusing but she said we didn’t need to know all the details, have another look over if you want to understand more fully).

Question 14

How does the body get vitamin A?

Answer 14

Through the diet

Question 15

What is vitamin A required for?

Answer 15

Healthy epithelium
Vision in dim light

Question 16

In which other conditions may vitamin A deficiency occur?

Answer 16

-Malnutrition
-Malabsorption syndromes e.g. coeliac disease

Question 17

What are some of the signs of vitamin A deficiency?

Answer 17

Bitot’s spots in conjunctiva*
Corneal ulceration

*important to remember that Bitot’s spots remain in conjunctiva for a while so may indicate past vitamin A deficiency rather than current

Question 18

There are many reaction that take place in response to light but what is the final outcome of these reactions?

Answer 18

Results in an action potential which is carried to the brain via optic nerve

Question 19

What is the visual field?

Answer 19

Everything seen with one eye, including the periphery

Question 20

Fovea?

Answer 20

Point of best visual acuity

Question 21

As the two optic nerves go through the optic foramen, they enter the middle cranial fossa and come together. What is the name of the region in which the two optic nerves come together?

Answer 21

Optic chiasm

Question 22

Which area number is the primary visual cortex centre situated in?

Answer 22

Area number 17

Question 23

Once the optic nerves have met at the optic chiasm, what happens?

Answer 23

The optic fibres cross over at the optic chiasm and moves down optic tracts and synapses at the LGB.

Question 24

What happens once the optic nerve synapses at the LBG?

Answer 24

Optic radiation radiates through temporal and parietal lobes until it reaches the occipital lobe.

Question 25

Images formed by the right half of the visual field go where?

Answer 25

Left side of occipital cortex -> and vice versa e.g. images formed by left side of visual field go to right side of occipital cortex

Question 26

Okay, bit of information first. Try to understand and answer the question :) We can describe the fibres coming from the eye as coming from the nasal/temporal region of the right/left eye. The temporal region is lateral while the nasal region in medial. There is a nasal and temporal side to both eyes. Therefore, a fibre from the temporal AND the nasal side of the right eye will travel down towards to the optic chiasm, as will a temporal AND nasal fibre on the left side. Only one of the two types of fibre (nasal and temporal) cross at the optic chiasm. Which fibres cross over to go to the opposite tract of the body?

Answer 26

Nasal fibres

Question 27

RECAP- name the intrinsic muscles of the eye.

Answer 27

Ciliaris muscle Constrictor pupillae Dilator pupillae.

Question 28

RECAP- name the extrinsic muscles of the eye.

Answer 28

Lateral rectus Superior rectus Medial rectus Inferior rectus Superior oblique Inferior oblique LPS

Question 29

RECAP- which CN supplies the superior oblique muscle?

Answer 29

CN IV (trochlear) ->remember what the man in anatomy labs said SO=sulphur which has a wee four down below so it's CN 4 which supplies SO

Question 30

RECAP- which CN supplies the lateral rectus muscle?

Answer 30

CN VI (abducent)

Question 31

RECAP- which CN supplies all the muscles of the eye EXCEPT the SO, LR?

Answer 31

Oculomotor nerve- CN III

Question 32

Which movement describes looking up?

Answer 32

Elevation of the eye

Question 33

Which movement describes looking down?

Answer 33

Depression of the eye

Question 34

Which movement describes looking away from the nose?

Answer 34

Abduction

Question 35

Which movement describes looking towards the nose ?

Answer 35

Adduction

Question 36

What is the name given to looking to the right?

Answer 36

Dextroversion

Question 37

What is the name given to looking to the left?

Answer 37

Levoversion

Question 38

Therefore, what is looking up and to the left called?

Answer 38

Levoelevation

Question 39

What is looking up and to the right called?

Answer 39

Dextroelevation

Question 40

What is looking down and to the left called?

Answer 40

Levodepression

Question 41

What is looking down and to the right called?

Answer 41

Dextrodepression

Question 42

What happens in intorsion?

Answer 42

Top of eyeball rotates towards nose

Question 43

What happens in extorsion?

Answer 43

Top of eyeball rotates away from nose

Question 44

Intorsion and extorsion cannot happen voluntarily. What may them occur?

Answer 44

When twisting or turning the head

Question 45

What is the primary action of the MR?

Answer 45

Adduction

Question 46

What is the primary action of the LR?

Answer 46

Abduction

Question 47

What are the primary, secondary and tertiary actions of the SR?

Answer 47

Primary= elevation Secondary= adduction Tertiary= abduction ->mnemonic to remember actions of superior and inferior rectus and oblique muscles= RADSIN (Recti ADductors, Superiors Introtors).

Question 48

What are the primary, secondary and tertiary actions of the IR?

Answer 48

Primary= depression Secondary= adduction Tertiary= extorsion

Question 49

What are the primary, secondary and tertiary actions of the SO?

Answer 49

Primary= intorsion Secondary= depression Tertiary= abduction

Question 50

What are the primary, secondary and tertiary actions of the IO?

Answer 50

Primary= extorsion Secondary= elevation Tertiary= abduction

Question 51

What is a squint/strabismus?

Answer 51

Misalignmentof the eyes

Question 52

What is the name of the squint when one eye rotates or turns inwards?

Answer 52

Convergent squint

Question 53

What is the name of the squint when one eye rotates or turns outwards?

Answer 53

Divergent squint

Question 54

Give two functional consequences of a squint.

Answer 54

Amblyopia- lazy eye Diplopia - double vision

Question 55

Which types of squint may result in diplopia/double vision?

Answer 55

Squints occurring as a result of a nerve palsy

Question 56

What is used to correct amblyopia @(lazy eye) in younger years?

Answer 56

Eye patch over normal eye to force squinting eye to work ->whooooooooooooo go me

Question 57

Describe the pupillary reaction to increased illumination.

Answer 57

Both pupils constrict via parasympathetic innervation.

Question 58

Describe the pupillary reaction to decreased illumination.

Answer 58

Both pupils dilate via sympathetic innervation.

Question 59

How do you assess pupillary reflex in a clinical setting?

Answer 59

Use pen torch in each eye to check for constriction. Then switch the pen to to other eye as both pupils should remain constricted.

Question 60

Afferent? Efferent?

Answer 60

Afferent= sensory Efferent= motor

Question 61

Nerve fibres destined for the pupillary reflex synapse where?

Answer 61

Edinger-Westphal nucleus (EWN)

Question 62

Why is there bilateral constriction of the pupil when the light is only shone in one eye?

Answer 62

The pupillary reflex fibres go to the EWN of both sides

Question 63

Anisocoria?

Answer 63

When the two pupils are not the same size

Question 64

What can cause anisocoria?

Answer 64

Trauma Horner's Syndrome

Question 65

If there is a third nerve palsy with an absent pupillary reflex, what should be considered?

Answer 65

Cerebral artery aneurysm

Question 66

Why does anisocoria occur in Horner's Syndrome?

Answer 66

Due to damage to the sympathetic innervation of the pupil.

Question 67

In those with Horner's Syndrome, what else might be noticeable?

Answer 67

Ptosis- eyelid droops Anhidrosis- loss of sweating on affected side