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ELM3 - nervous > lecture 25 - vision > Flashcards

lecture 25 - vision Flashcards

1
Q

What is the term for the ‘white of the eye’?

A

Sclera

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2
Q

What muscle controls lens shape for accomodation?

A

Ciliary muscle

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3
Q

What structure in the eye defines pupil diameter?

A

Iris

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4
Q

What is the function of the ciliary body?

A

Secretes aqueous humor

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5
Q

What fluid is found within the anterior chamber of the eye?

A

Aqueous humor

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6
Q

What fluid is found within the posterior chamber of the eye?

A

vitreous humor

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7
Q

Why does the retina need a good blood supply?

A

Relies on oxidative metabolism, so relies on a good supply of oxygen and gluocse

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8
Q

What is the function of the choroid of the eye?

A

Contains lots of blood vessels that provides blood to the deep retina

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9
Q

Where is the location of the deep retina?

A

At the back of the eye, on the outer part of the eyeball, but is deep to the light source that comes from the anterior

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10
Q

What condition arises when there is damage from raised intraocular pressure?

A

Glaucoma

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11
Q

What are the findings on ophthalmoscopy in diabetes?

A

Increased vascularisation

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12
Q

What are the findings on ophthalmoscopy in papilloedema?

A

Optic disc bulges

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13
Q

What are the 6 extraocular muscles that control eye movement?

A

Superior oblique, Inferior oblique, Lateral rectus, medial rectus, superior rectus, inferior rectus

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14
Q

Which cranial nerves control eye movement?

A

Oculomotor (III), trochelar (IV), abducens (VI)

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15
Q

Which extraocular muscles are controlled by the oculomotor nerve?

A

Superior rectus, Inferior rectus, medial rectus, inferior oblique

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16
Q

Which extraocular muscles are controlled by the trochlear nerve?

A

Superior oblique

17
Q

Which extraocular muscles are controlled by the abducens nerve?

A

Lateral rectus

18
Q

What is the relationship between the contraction state of the ciliary muscles and the shape of the lens?

A

Contracted muscles = lower tension and more rounded lens
Relaxed muscles = higher tension and more flattened lens

19
Q

What is the action of the ciliary muscles during near vision?

A

They contract to relax the zonular fibres and relax the lens so it becomes thicker and more spherical

20
Q

What is the pathophysiology of glaucoma?

A

There is build of aqueous humor in the front of the eye due to excessive production or blocked drainage. This increases pressure which damages eye blood vessels and the optic nerve.

21
Q

What are the steps in the pathway of visual information from the retina to the optic nerve?

A

Photoreceptor cells (rods/cones), bipolar cells, ganglion cells, axons of ganglion cells converge to form optic nerve

22
Q

What are the basic steps in the pathway of visual information from the optic nerve to the visual cortex?

A

optic nerve, optic chiasm, optic tract, lateral geniculate body, optic raditation

23
Q

What visual field defect occurs when there is a single optic nerve lesion?

A

mononuclear blindness (loss of vision in the ispilateral eye)

24
Q

What visual field defect occurs when there is an optic chiasm lesion?

A

Bitemporal hemianopia

25
Q

What type of visual field defect will often arise in patients with a pituitary tumor?

A

Bitemporal hemianopia (loss of peripheral vision) due to pressure on the optic chiasm

26
Q

What visual field defect occurs when there is a lesion to the optic tract?

A

Homonymous hemianopia (loss of vision on half of each each eye on the side opposite to the lesion)

27
Q

What visual field defect occurs when there is a lesion affecting Meyer’s loop?

A

Upper quadrantic anopia

28
Q

What visual field defect occurs when there is a partial lesion of the optic radiation?

A

Lower quadrantic anopia

29
Q

What visual field defect occurs when there is a PCA infarct?

A

Homoonymous hemianopia with macular sparing (vision in the centre of each eye is intact)

30
Q

What is the purpose of the retino-hypothalamic tract?

A

Convey information about light for circadian rhythm, body clock, sleep-wake cycles

31
Q

What is the function of the superior collicullus-visual pathway?

A

Role in unconscious automatic control of orientation to visual stimuli

32
Q

What are the 2 types of light-sensitive receptors in the retina?

A

Cones, rods

33
Q

What is the function of cones in the eye?

A

Colour vision - each cone can absorb different wavelengths of light

34
Q

What is the function of rods in the retina?

A

Grey-scale vision - vision in low light levels

35
Q

Which type of light receptor cell operates in higher light intensity?

A

Cones - can only see colour at high light density

36
Q

Which type of light receptor cell is more sensitive?

A

Rods

37
Q

Where in the retina is the highest density of cones?

A

Fovea

38
Q

How are cones adapted to see different wavelengths of light?

A

There are 3 different types of cones, with 3 different cone opsins that have sensitivity to red, blue and green

ELM3 - nervous (29 decks)

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