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Ophthalmology SOH > Physiology > Flashcards

Flashcards in Physiology Deck (67):
1

Aqueous humour - where is it produced?

Ciliary body

2

Aqueous humour - where is it secreted from?

Ciliary process (internal folds of ciliary body)

3

Aqueous humour pathway

Secreted into posterior chamber (nourishes lens)
Passes through the pupil to the anterior chamber (nourishes cornea)

4

Aqueous humour - where does it drain

Scleral venous sinus through the canal of schlemm

5

Aqueous humour is mainly found in the ANTERIOR/POSTERIOR segment of the eye?

Anterior

6

Aqueous humour - function

Maintains intra-ocular pressure
- the IOP depends on the balance between the production and reabsorption of aqueous humour

7

Vitreous humour - definition

Clear fluid with a jelly like consistency

8

Vitreous humour is mainly found in the ANTERIOR/POSTERIOR segment of the eye?

Posterior

9

Where are photoreceptors found

Posterior part of the retina

10

Photoreceptors - functions

Converts light into neural signals that can stimulate biological processes

11

2 types of photoreceptors

Rods
Cones

12

There is increased visual acuity if there are MORE/LESS photoreceptors present

More

13

There is increased visual acuity if the photoreceptors are spaced very close together. True or false?

True

14

Rods - light conditions

Dim light
When light conditions are not good
Low levels of light
Night vision, peripheral vision

15

Rods - where are they located

Peripheral retina

16

Rods - photoreceptor spacing

Large spacing between photoreceptors

17

Rods - high/low light sensitivity

High

18

Rods - high/low visual acuity

Low

19

Cones - light conditions

Bright light
Normal daylight
For seeing things in colour
Detail

20

Cones - where are they located

Central retina

21

Cones - photoreceptor spacing

Minimal spacing between photoreceptors

22

Cones - high/low light sensitivity

Low

23

Cones - high/low visual acuity

High

24

Colour vision - rods/cones

Cones

25

Short wave cone produces which colour?

Blue

26

Middle wave cone produces which colour?

Green

27

Long wave cone produces which colour?

Red

28

When exposed to light, Na+ levels increase/decrease ?

Decrease
- due to the closure of cGMP gated Na+ channel

29

Decreased Na+ levels causes the membrane potential to become more positive/negative?

Negative
- Vm hyperpolarises

30

In the absence of light, Na+ levels increase/decrease?

Increase
- due to the opening of cGMP gated Na+ channel

31

Increased Na+ levels causes the membrane potential to become more positive/negative?

Positive
- Vm depolarises

32

What are the visual pigment molecules called?

Rhodopsin

33

2 components of rhodopsin

Retinal (vitamina A derivative)
Opsin (GPCR)

34

Where in the retina is the fovea located?

In the centre of the retina, inside the macula

35

Infant presents with a visual problem in one eye. What is the initial management?

Put eye patch over GOOD eye.
Make the patient use their bad eye to force the brain to rely on signals from the bad eye. This helps the brain develop properly

36

Emmetropia - definition

No refractive error
The eye has no visual defects

37

Hyperopia - definition

Vision is better for distant than for near objects
(farsightedness)

38

Hyperopia - parallel rays are focussed in front of / behind the retina ?

Behind

39

Myopia - definition

Vision is bette for near than for far away objects
(short sightedness)

40

Myopia - visual images come in to focus in front of / behind the retina ?

In front of

41

Everything from the right visual field hits the eye at the ____ retina of the right eye and the ____ retina of the left eye

Nasal retina - right eye
Temporal retina - left eye

42

Light from objects in the right visual field is processed by the RIGHT/LEFT primary visual cortex

Left

43

Light from objects in the lower visual field is processed by the UPPER/LOWER part of the primary visual cortex

Upper

44

What happens when we blink

Lacrimal fluid runs over the eye and this prevents the eye from drying out.
Helps remove foreign bodies from the eye

45

Which nerves (sympathetic/parasympathetic) cause dilation of the pupil?

Sympathetic

46

How does light reach the retina?

It goes through the pupils

47

Dilated pupil allows more/less light to reach the retina?

More

48

Which muscle is responsible for pupillary dilation?

Dilator pupillae muscle

49

Location of the dilator pupillae muscle

Located around the external circumference of the iris

50

Mydratic pupil

An abnormally sustained pupillary dilation

51

Mydratic pupil - causes

eye drops (drugs)
diseases
trauma
CNIII pathology (constrictors not working at all)

52

Constricted pupil allows more/less light to reach the retina?

Less

53

Which nerves (sympathetic/parasympathetic) cause constriction of the pupil?

Parasympathetic

54

Which muscles is responsible for constriction of the pupil?

Sphincter pupillae muscle

55

Location of the sphincter pupillae muscle

It encircles the pupil
Around the internal circumference of the iris

56

Mitotic pupil

Abnormally sustained pupillary constriction

57

Mitotic pupil - causes

Diseases (Horner's syndrome)
Opiate drugs

58

Pupillary light reflex (direct)

Shine a torch into one eye
Direct light reflex (constriction) in the stimulated eye

59

Pupillary light reflex (consensual)

Shine a torch into one eye
Constriction occurs in the non-stimulated eye

60

Which nerves (sympathetic/parasympathetic) are responsible for far (distant) vision

Sympathetic nerves

61

In far (distant) vision, the ciliary muscle contracts/relaxes ?

Relaxes

62

In far (distant) vision, the suspensory ligaments contract/relax

Contract

63

In far (distant) vision, the lens is flat/spherical

Flat

64

Which nerves (sympathetic/parasympathetic) are responsible for near vision

Parasympathetic nerves

65

In near vision, the ciliary muscle contracts/relaxes?

Contracts

66

In near vision, the suspensory ligaments contract/relax?

Relax

67

In near vision, the lens is flat/spherical

Spherical