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Nervous System > Vision 1 & 2 > Flashcards

Vision 1 & 2 Flashcards

1
Q

What is refraction?

A

The bending of light as it passes from one medium to another

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2
Q

Which structures in the eye allow for refraction?

A

Cornea and lens

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3
Q

What is accommodation?

A

The changes occurring in both eyes as it focuses from a distant object to a close object

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4
Q

What three things comprise accommodation?

A

Lens change shape, pupil constricts and eyes converge

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5
Q

Which muscle allows the lens to become thicker

A

ciliary muscles

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6
Q

What effect does thickening the lens have on the focus?

A

It allows focusing on close objects

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7
Q

Which nerve fibres causes ciliary body contraction

A

Parasympathetic

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8
Q

What is convergence?

A

The turning in of the eyes when focussing on an object up close

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9
Q

Which muscles are responsible for convergence of the eyes?

A

Medial rectus muscles

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10
Q

What is myopia?

A

Short-sightedness

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11
Q

What is hyperopia?

A

Long-sightedness

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12
Q

What is astigmatism?

A

Non spherical curvature of the cornea or lens

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13
Q

What is presbyopia?

A

Long-sightedness of old age

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14
Q

What happens to a persons vison in shortsightedness?

A

Close objects look clear and distant objects appear hazy

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15
Q

What is the most common cause of short-sightedness?

A

Eyeball is too long, making the image form in front of the retina

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16
Q

What are the symptoms of short-sightedness?

A

Headaches, not able to see distant objects, divergent squint in infants and preverbal children and loss of interest in sports/people in adults

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17
Q

How is short-sightedness corrected?

A

Biconcave lenses (glasses or contact lenses) or laser eye surgery

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18
Q

What happens to a persons sight in far-sightedness?

A

Close objects look hazy and distant objects appear clear

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19
Q

What is the cause of far-sightedness?

A

Eyeball too short or cornea + lens too flat making the image appear behind the retina

20
Q

What are the symptoms of far-sightedness?

A

Eyestrain and convergent squint in children/toddlers

21
Q

How is far-sightedness corrected?

A

Biconvex glasses, contact lenses or laser eye surgery

22
Q

What happens to a person’s vision in astigmatism?

A

Close and distant objects appear hazy

23
Q

What is the cause of astigmatism?

A

The surface of the eye has different curvatures in different mediums

24
Q

What happens to vision in presbyopia?

A

Seeing near objects becomes difficult

25
Q

What is the cause of presbyopia?

A

With age the lens gets less mobile/elastic and when the ciliary muscle contracts it is less able to change shape

26
Q

How is presbyopia corrected?

A

Biconvex “reading glasses”

27
Q

What is phototransduction?

A

The conversion of light energy to an electrochemical response by the photoreceptors (rods and cones)

28
Q

What is rhodopsin made up of?

A

Opsin + 11-cis Retinal

29
Q

How does bleaching of the visual pigment result in phototransduction?

A

Phototransduction

30
Q

What role does vitamin A play in the visual pigment?

A

Visual pigment regeneration

31
Q

Where do all fibres from the eye pass?

A

Through the optic nerve to the optic chiasm

32
Q

What happens to the fibres at the optic chiasm?

A

The medial/nasal fibres cross to the opposite side

33
Q

What fibres does the optic tract contain?

A

Fibres from the temporal half of the ipsilateral eye and the nasal fibres from the contralateral eye

34
Q

Where do the optic radiation fibres go?

A

Primary visual cortex in the occipital lobe

35
Q

Name the six extrinsic ocular muscles of the eye

A

Medial rectus, lateral rectus, inferior rectus, superior rectus, superior oblique and inferior oblique

36
Q

Where do the recti muscles of the eye arise from?

A

An annular fibrous ring at the apex of the orbit

37
Q

Where does the superior oblique muscle arise from?

A

Roof of the orbit posteriorly

38
Q

Where does the inferior oblique muscle arise from?

A

Floor of the orbit anteriorly

39
Q

What does the levator palpebrae superioris do?

A

It elevates the upper eyelid

40
Q

Which muscle is supplied by the trochlear nerve?

A

Superior oblique

41
Q

Which muscle is supplied by the abducent nerve?

A

Lateral rectus

42
Q

Which nerve innervates the extrinsic muscles of the eye (apart from LR and SO)?

A

Oculomotor nerve

43
Q

Where is constrictor pupillae found?

A

At the pupillary border in the iris

44
Q

Where does the dilator pupillae lie?

A

Radially in the iris

45
Q

What is the innervation of the ciliaris and constrictor pupillae muscles?

A

Parasympathetic fibres from the oculomotor nerve

46
Q

What is the innervation of the dilator pupillae muscle?

A

Sympathetic fibres

Nervous System (16 decks)

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